This list is our whole library. Some studies sit behind a pack. Others changed how we design. Some settled a claim we will not make. The categories are named for what the studies are about. We check each study again when we build a pack on it. A name you can tap leads to the study itself. We add the tap only after we have opened the study and read it.
Each study belongs to one main category. It can also appear in other categories it fits. That is why the category counts add up to more than the number of studies.
1Strong
Play works best when the kid leads it.
Yogman, Garner, Hutchinson, Hirsh-Pasek & Golinkoff (2018), Pediatrics 142(3), e20182058; AAP clinical report (reaffirmed January 2025, per AAP listing).
Strong (as consensus): official AAP clinical report, reaffirmed 2025; an evidence-informed consensus statement, not a trial
Who was studied: A second report from the same group of doctors. It focuses on young kids.
What they found: Real play is play a kid picks for himself. Kids enjoy it. Nobody assigns it. It builds language, early math, and self control. The doctors even tell pediatricians to prescribe play.
What it means for you: You set the stage. Your kid runs the play. That split is the heart of every pack.
2Moderate
Play comes in kinds. Adults can help more or less.
Zosh, Hirsh-Pasek, Hopkins, Jensen, Liu, Neuman, Solis & Whitebread (2018), Frontiers in Psychology 9, 1124. (Companion LEGO Foundation white paper, Zosh et al. 2017, Learning through play: a review of the evidence, index only, describes optimal playful learning as joyful, meaningful, actively engaging, iterative and socially interactive)
Moderate: influential conceptual synthesis from leading researchers, but a framework paper, not new data
Who was studied: A review paper by play researchers. No new experiment.
What they found: Play runs on a line. At one end kids play free. At the other an adult teaches through play. In the middle sits guided play. The adult sets it up and the kid directs it. Research backs that middle spot.
What it means for you: Our packs live in the middle. We bring the frame. Your kid brings the direction.
3Thin
Kids move in bursts. Not in long runs.
Bailey et al. (1995), Medicine & Science in Sports & Exercise 27, 1033 to 1041.
Thin: the primary study is small and old; the consistency of the pattern across re-analyses raises confidence in the pattern (intermittency), not in any exact number
Who was studied: 15 kids, ages 6 to 10, watched as they played.
What they found: Bursts of movement lasted seconds. Most were under half a minute. Rest came in tiny pauses all through play.
What it means for you: A pack activity is built from short bursts with natural pauses. It never asks a kid to push flat out for 20 minutes.
4Strong
A little each day beats a lot at once.
Cepeda, Pashler, Vul, Wixted & Rohrer (2006), Psychological Bulletin 132(3), 354 to 380.
Strong for the spacing effect itself (one of the most replicable findings in learning science); Moderate for transfer to daily play sessions, which are not verbal recall
Who was studied: A review of 317 experiments. Most tested adults learning words.
What they found: Practice spread out over time beat crammed practice in almost every test. The longer you want to remember, the wider the gap should be.
What it means for you: This is why packs run daily and short. One long weekly blast is the weaker shape. The proof comes from memory tests, not play, and we say so.
5Moderate
Lessons spread over days stuck better.
Vlach & Sandhofer (2012), Child Development 83(4), 1137 to 1144.
Moderate: a true experiment in the exact age band with an educationally realistic task, but a single small study
Who was studied: 36 kids, ages 5 to 7, in a real experiment.
What they found: Kids who got one science lesson a day for four days used the ideas better a week later. Kids who got all four lessons in one day did worse. Same lessons. Same total time.
What it means for you: One short session a day is the right unit. This one was tested in kids in our age band.
6Moderate
Kids engage when they get both structure and choice.
Jang, Reeve & Deci (2010), Journal of Educational Psychology 102(3), 588 to 600.
Moderate: the canonical study for "structure + autonomy," but correlational and in the wrong age band for direct transfer
Who was studied: About 1,600 students in grades 9 to 11. Older than our kids.
What they found: Classes with clear structure and real choice had the most engaged students. One without the other did less well.
What it means for you: Every pack has a fixed frame. Same time. Same length. Clear end. Inside that frame the kid makes real choices. The study used teens, so we treat it as a strong hint, not proof for age 7.
7Moderate
Steady family routines go with calmer kids.
Fiese, Tomcho, Douglas, Josephs, Poltrock & Baker (2002), Journal of Family Psychology 16(4), 381 to 390.
Moderate: the field's canonical review, honest about weak designs; direction of findings is consistent
Who was studied: A review of 32 studies over 50 years. Most of the young kid evidence is from the preschool years.
What they found: Families with steady routines had parents who felt more able and kids who settled better. The proof shows a link. It does not prove cause.
What it means for you: Packs stick to the same time each day and open and close the same way. We say routines go with calmer homes. We never promise a routine will fix behavior.
8Moderate
A new habit takes about two months. Not 21 days.
Lally, van Jaarsveld, Potts & Wardle (2010), European Journal of Social Psychology 40(6), 998 to 1009.
Moderate for adults; Thin for transfer to parent-delivered child routines (different population, and the parent, not the child, is the habit-former here)
Who was studied: 96 adults. Each one built a single new daily habit.
What they found: For the person in the middle, the habit felt automatic after about 66 days. The full range ran from 18 to 254 days. Missing one day did not wreck it.
What it means for you: Plan on two months of steady cues before it feels easy. Same time. Same place. And a missed day is fine. The 21 day line is a myth with no study behind it. This study used adults, so we hold it loosely for family routines.
9Moderate
Endings go best at a natural stop.
Hiniker, Suh, Cao & Kientz (2016), Proceedings of CHI '16, ACM, DOI 10.1145/2858036.2858278; institutional report: University of Washington News (2016).
Moderate: direct observation of real family transitions, but observational, screen-specific, and in under-6s
Who was studied: 55 families with kids ages 1 to 5. Younger than our band.
What they found: Most screen endings were fine. About 6 in 10 got a flat reaction with no fuss. Endings inside a routine or at a natural break went best. Kids who got a two minute warning were more upset, not less.
What it means for you: Each pack ends with a last step that is a natural stop. The ending is part of the game. We do not sell the two minute warning as a proven tool.
10Moderate
A warning alone did not get young kids to stop.
Wilder, Nicholson & Allison (2010), Journal of Applied Behavior Analysis 43(4), 751 to 755.
Moderate: rigorous single-case experimental designs with a consistent null, but n = 3, clinical noncompliance, preschoolers, and a compliance (not play-transition) context
Who was studied: 3 boys, ages 4 to 5, in a careful lab study.
What they found: Warnings at two minutes and at one minute changed almost nothing. Kids stopped only when a steady consequence followed the warning.
What it means for you: Packs end the same way every time. The end is built in and expected. A warning by itself is not the plan.
11Thin
One older study found warnings did help.
Zeece & Crase (1982), Journal of Psychology 112(2), 269 to 274, DOI 10.1080/00223980.1982.9915384.
Thin: one small, old study, preschool population, verified at the canonical page 2026-11-04
Who was studied: 40 preschool kids, ages 3 to 6, in a 1982 study.
What they found: A spoken warning before a change made the switch easier in this study. That clashes with the later study above.
What it means for you: The honest word on warnings is mixed. Some families swear by them. The science does not settle it. Routine and a natural end carry more proof.
12Thin
Multi-session project work in elementary classrooms is linked to better achievement and critical thinking.
Project Based Learning and Student Academic Achievement (2024), Journal of Science Education; and a second synthesis on critical thinking in elementary science, held at DOAJ
Thin to moderate for the engagement and learning value of multi-session projects in classrooms; thin for transfer to a voluntary home arc, which this literature never tests
Who was studied: Elementary school students in classroom project-based learning studies, nearly all teacher-led, running for weeks, with attendance compulsory.
What they found: One synthesis pooled eight studies, with effect sizes from 0.13 to 3.70 and a pooled value of about 1.2, the largest effects at elementary level. A second synthesis on elementary science reported a moderate effect on critical thinking. The spread of effects is wide, the first synthesis is small and from a low-tier outlet, and neither measures voluntary home completion.
What it means for you: An arc pack can borrow the shape of multi-session making: one visible artifact, built across days. We make no completion guarantees, and we never quote the pooled effect.
13Background
Short sessions spread out beat one long block.
The spacing literature, as invoked in brief (§13); no single study named there
Invoked as settled in §13; no named citation in brief
Who was studied: The spacing research as a whole. The anchor study is a review of hundreds of learning tests.
What they found: Learning spread across short sittings sticks better than the same time in one long block. The number board game in BLD-04 fits the same shape. Its gains came from about one hour total, split into short sessions.
What it means for you: An hour of play is a stack of short sessions with breaks, not one long stretch. The 30 minute session is the unit everything is built from. We never sell one forced hour as the right dose.
14Moderate
Focus grows fast between 5 and 9.
Betts, McKay, Maruff & Anderson (2006), Child Neuropsychology 12(3), 205 to 221. (Same study as HOLD-07, filed there for session sizing; filed here as the architecture sizing anchor)
Moderate: solid developmental study, but small N and laboratory tasks, not free play
Who was studied: 57 kids, ages 5 to 12, on standard attention tests.
What they found: Focus jumped between ages 5 and 9 and then leveled off. Hard tasks wore every age down faster than easy ones. The study sets no time limit for a play session.
What it means for you: Packs for ages 5 to 7 use short parts and lots of change. One long hard task is the wrong shape at that age. And we never quote the folk rule about minutes of focus per year of age. No solid study backs it.
15Background
Kids pay attention longest to activities they chose themselves.
Study not named in brief (§7)
Not graded in brief; stated as a finding in §7
Who was studied: Three-year-olds, in different teaching setups.
What they found: Activities the child picked held attention the longest. Activities an adult picked came second. Activities an adult simply presented came last. We have to be straight with you here. We could not find the published study behind this one.
What it means for you: The child leads. That is the default shape of every pack. But we hold this one loosely until the study turns up.
16Checked
An old rule of thumb ties focus time to age. Treat it as a guess.
Folk rule, as recorded in brief (§7); no study named
Folk rule, recorded at that strength (§7)
Who was studied: No study. This is a rule passed around by teachers and parents.
What they found: The rule says a child can focus on a task he did not choose for about two to three minutes per year of age. That means roughly 15 to 20 minutes at age 7. Chosen tasks kids care about run far longer. No solid study backs the numbers.
What it means for you: We use the range only to size a session. We never promise your child will focus for a set number of minutes.
17Background
Kids say good play means feelings, freedom, and friends. Not lessons.
Aarhus University (2026), Frontiers in Psychology
Not graded in brief (§5, item 8)
Who was studied: 104 children told their play stories. Then hundreds more children rated statements about play.
What they found: Kids defined good play by imagination and wild, energetic play. Silliness and bending the rules counted too. So did playing with others. Learning goals and good behavior did not define it.
What it means for you: Missions are built to feel like play to the child. Silliness and a little rule bending are allowed on purpose. We never pitch a mission to a child as a lesson.
18Background
Pretend play warms up slowly. It peaks 10 to 15 minutes in.
SWPS University study, as cited in brief (§5, item 8)
Not graded in brief
Who was studied: The brief does not name the children or their ages.
What they found: Engagement in pretend play climbed after play began. It peaked about 10 to 15 minutes in. It did not peak at the start.
What it means for you: Packs open gently and ask for more later. We never judge a mission by its first two minutes.
19Moderate
Boredom might feed creativity later. The proof is in adults only.
Mann & Cadman (2014)
Moderate heading in brief (§5, item 7) with the child claim downgraded to suggestive
Who was studied: Adults. No children took part.
What they found: Adults who did a boring task first came up with more creative ideas after. Nobody has shown this in children. For kids it is a hint and nothing more.
What it means for you: We leave some open space in a pack and do not panic about it. We never claim downtime in a pack makes your child more creative.
20Strong
Focus grows fast from 5 to 9. Then it levels off.
Betts, McKay, Maruff & Anderson (2006), Child Neuropsychology 12(3), 205 to 221.
Strong: direct age range, standardized battery, clear trajectory
Who was studied: 57 children, ages 5 to 12, on standard attention tests.
What they found: Focus jumped from age 5 to 6 and again to 8 to 9. Then it flattened out toward age 10 to 12. Tasks with a heavy mental load hurt focus at every age.
What it means for you: A 10-year-old can hold a mission longer than a 5-year-old. So the youngest kids get shorter and simpler missions. One ladder for all ages would be wrong.
21Strong
Splitting attention between two things at once is the real bottleneck.
Talalay (2024), Psychology in the Schools 61(6), 2223 to 2239.
Strong: large N, in-range, effect pattern replicated across measures
Who was studied: 199 children, ages 6 to 12.
What they found: Picking out one thing from a busy scene improved bit by bit with age. Handling two streams of information at once improved a lot between 6 and 12. Trying to track two things at once badly hurt performance. The youngest children suffered most.
What it means for you: One mission thread at a time. We never ask a young child to follow two things at once.
22Moderate
Deep focus comes when the challenge is high and the skill matches it.
Rathunde & Csikszentmihalyi (2005), American Journal of Education 111(3), 341 to 371.
Moderate: strong ESM design, but age-out-of-range and school-context confound
Who was studied: About 290 middle school students. They are older than our kids. Researchers paged them at random moments and asked what they felt.
What they found: Montessori students reported more flow and undivided interest in schoolwork than students in regular schools. Flow was strongest when challenge and skill were both high and in balance. Feeling the work mattered and having some control helped too. There was no gap in free time activities.
What it means for you: Missions let the child pick the difficulty and set the pace. But this study used older kids in schools. We treat it as a direction, not proof for age 7.
23Thin
Teens engage most when work is hard, matched to skill, and theirs to steer.
Shernoff, Csikszentmihalyi, Schneider & Steele Shernoff (2003), School Psychology Quarterly 18, 158 to 176.
Thin (for this product): classic flow-ESM pattern but older sample, no 5 to 10 replication in hand
Who was studied: 526 US high school students. Well above our age band.
What they found: Engagement peaked when challenge and skill were both high and balanced. Work that felt relevant raised it. So did student control. Kids engaged more in solo and group work than in lectures, videos, or exams.
What it means for you: Balance, relevance, and control point the same way as the study above. Nobody has pinned down the exact balance point for ages 5 to 10. We will not pretend otherwise.
24Moderate
Kids who rarely read still get lost in a good story by age 10.
Prezioso & Harris (2025), Psychology of Aesthetics, Creativity, and the Arts 19(4), 747 to 759.
Moderate: in-range, but self-report and small N
Who was studied: 66 children, ages 9 to 11.
What they found: Children described getting absorbed in stories through focus, feelings, and pictures in the mind. At age 9, keen readers absorbed more than rare readers. By 10 to 11 the gap was gone. Rare readers absorbed just as much.
What it means for you: Story missions are not just for bookish kids. A child does not need to call himself a reader to get pulled in.
25Moderate
Thrill-seeking kids skip reading. A story that grabs them fixes that.
Jensen, Imboden & Ivic (2011), Scientific Studies of Reading 15(6), 541 to 558.
Moderate: survey, but in-range with a clean moderation pattern
Who was studied: 120 children in grades 4 and 5.
What they found: Children who seek strong sensations read less for fun. Boredom sat in the middle of that link. But when a story truly pulled a thrill seeker in, he read like anyone else. Science fiction and fantasy pulled hardest.
What it means for you: For a thrill-seeking child, missions start fast and drop him straight into the world. Quiet and gentle is the wrong door for him.
26Moderate
A story that grips kids makes them stick longer with hard thinking after.
Dore, Smith & Lillard (2017), Child Development Research, Article ID 6838079.
Moderate: experimental, in-range, but narrative-engagement measure is brief
Who was studied: Two studies. 96 children ages 7 and 10, then 104 more children.
What they found: Children who got pulled into a story about a professor spent more time on a hard puzzle toy after it. Telling kids to step into the character's shoes pulled them in deeper. A boring lead-in did not do this.
What it means for you: A short story hook can open a thinking mission. The hook has to grip, though. Just reading any story first is not enough.
27Moderate
A token game with a dash of luck got kids doing more math, and getting more right.
Eckert, Scherenberg & Klinke (2023), Frontiers in Psychology 14:1077406.
Moderate: in-range and analogue (non-digital), but small pilot, quasi-experimental
Who was studied: 39 elementary school children, average age about 8 and a half. The game ran for two weeks.
What they found: Children playing the token game finished more math exercises than before. They also solved more correctly than the group without the game. The surprise in the rewards seems to be what pulled them.
What it means for you: A small luck element can live inside a skill game. Pure luck games are not the engine. And two weeks is all this study ran, so we claim nothing long term.
28Moderate
Game elements beat none. Surprise rewards beat set rewards by nothing.
Ghanbari, Mahdavinasab & Mohammadhasani (2024), Interdisciplinary Journal of Virtual Learning in Medical Sciences 15(2), 180 to 191.
Moderate: quasi-experimental, in-range, and the null is the point
Who was studied: 84 sixth graders, split into surprise reward, set reward, and plain online learning groups.
What they found: Both game groups learned more than the plain group. The surprise reward group scored a little higher than the set reward group. That gap was too small to count as real.
What it means for you: Steady and predictable rewards are fine. Surprise is flavor, not a proven booster. We will not tell you otherwise.
29Thin
Chance games made math feel safer. They did not build confidence.
Nisbet & Williams (2009), Australian Mathematics Teacher (chance games in maths).
Thin: small, short, borderline age, no effect sizes reported
Who was studied: Two Year 7 classes, ages about 11 to 12. Just above our band. They played six chance games over two weeks.
What they found: The children enjoyed math more and wanted to do more of it. They felt less anxious about chance and saw more use in the subject. Their confidence did not rise in any way that counted.
What it means for you: A short chance game can be a gentle first step into number play. We never promise it makes a child confident.
30Strong
How funny a child is depends heavily on who he plays with.
Paine, Hashmi, Fink, Mitchell & Howe (2025), Communications Psychology 3:76.
Strong: in-range, observational, partner effects modelled properly
Who was studied: 130 UK children, ages 5 to 7. Researchers coded humor in their play.
What they found: The play partner alone explained 42.8 percent of the differences in how much humor a child produced. The same child could be hilarious with one partner and flat with another.
What it means for you: Silly missions work best in pairs, where kids bounce off each other. A joke script printed on a card cannot carry humor alone.
31Thin
Babies who laughed copied a silly demo more. That is all this one can say.
Esseily, Rat-Fischer, Somogyi, O'Regan & Fagard (2016), Cognition & Emotion 30(4), 817 to 825. (DOI confirmed on the article itself; the university repository URL recorded earlier was truncated at the source and is replaced by the DOI)
Thin (for this product): mechanism suggestion only, far below age range
Who was studied: 53 babies, 18 months old. Far below our age band.
What they found: Babies who laughed at a funny tool demo copied the action far more often. About 94 percent of the laughers used the tool right, against 25 percent in the plain demo. The researchers warn that happy temperament, not humor itself, may explain it.
What it means for you: A silly demo before a fiddly task is a cheap thing to try. This study cannot prove humor helps learning at ages 5 to 10.
32Moderate
Team games versus rival games changed no behavior. Kids liked team games more.
Eriksson, Kenward, Poom & Stenberg (2021), Scandinavian Journal of Psychology 62, 355ff.
Moderate: RCT-ish design, but ages 4 to 6 and one game set
Who was studied: 65 children, ages 4 to 6, playing board games in groups of four over six weeks.
What they found: Cooperative and competitive games produced the same kind and unkind behavior after play. Neither made children nicer or nastier. The children enjoyed the cooperative games more.
What it means for you: Either style of rules is allowed. We lean cooperative because kids enjoy it more. We never claim rival games harm children or team games make them kind.
33Thin
Kids engage most with adults and peers together. Not peers alone.
Shernoff & Vandell (2007), Journal of Youth and Adolescence 36, 891 to 903.
Thin (for this product): above-range ESM, but the adult+peer pattern is the only duration-relevant social finding in hand
Who was studied: 165 middle school students. Above our band. Researchers sampled their moments over time.
What they found: Engagement ran highest in sports and arts activities. Activities with both adults and peers present beat activities with peers only.
What it means for you: Some missions want a grown-up nearby. Some want a partner. We do not assume a solo mission holds a child the same way. This study used older kids, so we hold it at hint strength.
34Moderate
A 10 minute movement break reset focus. Five and 20 minutes did not.
Howie, Beets & Pate (2014), Mental Health and Physical Activity 7(2), 65 to 71.
Moderate: in-range, within-subjects, but dose pattern is non-monotonic and needs replication
Who was studied: 96 children in grades 4 and 5. Each child tried every break length.
What they found: After a 10 minute exercise break, children stayed on task 87.6 percent of the time. Sitting still gave 77.1 percent. Breaks of 5 and 20 minutes showed no clear gain.
What it means for you: A movement card of about 10 minutes can sit mid session as a reset. Length matters here. Any old break will not do.
35Moderate
Movement breaks lifted math scores. They did not lift thinking control tasks.
Howie, Schatz & Pate (2015), Research Quarterly for Exercise and Sport 86(3), 217 to 224.
Moderate: same sample as HOLD-30, so not independent replication
Who was studied: The same 96 children as the study above, ages 9 to 12. Same group, so this is not a second proof.
What they found: Math scores rose after 10 and 20 minute exercise breaks. Scores on self control and planning tasks did not move at all.
What it means for you: A movement reset can come right before a counting or math mission. We never claim breaks sharpen self control. The test looked and found nothing.
36Moderate
Three short active breaks a day raised movement and focus over 12 weeks.
Li, Liu & Zhao (2026), Frontiers in Public Health 14:1905069.
Moderate: very large RCT, but single site and the 5-min dose conflicts with HOLD-30's null for 5 minutes (different outcome/dose schedule)
Who was studied: 1,248 children in grades 1 to 6, in a large randomized study over 12 weeks.
What they found: Children with three 5 minute active breaks a day moved much more and sat much less. Their focus scores rose sharply. Younger children and weak focus children gained most. Note the clash. The study above found 5 minute breaks did nothing. The setup differed, and we do not pretend the two agree.
What it means for you: Short movement breaks sprinkled through a day are a safe bet. We just cannot tell you the one true break length. Nobody can yet.
37Moderate
Bored young kids mostly go find a person or a toy. That is how they cope, full stop.
Anderson & Perone (2024), Journal of Experimental Child Psychology 243, 105919.
Moderate: in-range-adjacent, but coping is not creativity
Who was studied: 130 children, ages 4 to 6.
What they found: Boredom worked in these young children much as it does in adults. When bored, most children asked a parent to play or picked up toys. The researchers expected certain boredom types to match certain coping moves. That link came up empty.
What it means for you: A pack can treat boredom as a cue card. "You are bored. Pick a toy or find a person." This study shows coping, not creativity. We claim nothing more from it.
38Thin
Kids left to beat boredom themselves leaned in harder. Early word only.
Perone, Vaughan, Anderson & Weybright (2026), Infant and Child Development 35(4), e70119.
Thin: secondary sourcing only; treat as a lead, not an entry-grade finding
Who was studied: Children, but we could not confirm the exact number or ages. This entry rests on a summary by others, not the paper itself.
What they found: Children whose parents let them sort out boredom on their own showed brain activity tied to moving toward a task. They showed it even on a boring task.
What it means for you: At most, this is an idea to test. Let a child sit with boredom a short while before a mission lands. We make no brain claims from this one.
39Moderate
Team play gave the warmest feelings about math games. Scores did not move.
Ke (2006), Proceedings of the 7th International Conference on Learning Sciences, pages 313 to 320.
Moderate: in-band, real games, four weeks; but one game set, class-level assignment, and a self-reported attitude outcome
Who was studied: 124 fifth graders in eight classes. They played math games twice a week for four weeks, as teams, as rivals, or alone.
What they found: The team setup produced the most positive feelings about the activity. Test scores did not differ across the three setups. Family income changed how the setups landed, so one size did not fit all.
What it means for you: Team framing helps when the problem is how a child feels about starting. That is the stand-off moment, and it is a feelings problem. We never promise team play raises scores. In this study it did not.
40Moderate
Picking from two held young kids longer than picking from six or seven.
Maimaran (2017), Judgment and Decision Making 12(3), 198 to 207.
Moderate: three consistent experiments with direct engagement durations and a built-in null control, but preschoolers only, so it licenses the band's lower edge as an extrapolation, not a measurement
Who was studied: Three experiments with children ages 4 to 5. Below our band. Groups ran from 42 to 59 children.
What they found: Children who picked a book or game from a set of two played with it longer. Picking from the big set also took longer and felt harder. The children said they preferred the big set. Set size changed nothing about how much of a chosen snack they ate, so the effect sits in engagement, not in everything.
What it means for you: Decision points offer two options, most of all at ages 5 to 6. A wall of options is not freedom. It is a leak. This was measured in preschoolers, so we claim it for the band's lower edge only.
41Moderate
Kids who get bored a lot are the kids who switch gears slowly.
Zhao & Uehara (2025), Frontiers in Psychology 16:1579642.
Moderate: in-band, executive function measured by performance rather than report, but a small exploratory sample, boredom measured by single-item parent ratings, and two cultural contexts only
Who was studied: 89 children, ages 6 to 8, in Japan and China. Their thinking skills were tested directly. Parents rated daily boredom.
What they found: Children with slower switching between rules were rated as bored more often in daily life. The link held across all three language groups. Boys reported more boredom during the test tasks themselves. Memory span and self control showed no link to boredom at all.
What it means for you: A boredom-prone child gets missions with more switches, variety, and rule changes built in. The link runs through switching, so the design answers it. This study shows a link, not a fix. Nobody has shown that training switching cures boredom.
42Moderate
The kids glued to screens are the boredom-prone ones.
Uehara & Ikegaya (2025), Frontiers in Psychology.
Moderate: a decent sample, squarely in-band, with large group differences; correlational, mother report only, one country, and 301 of the mothers also appear in a companion study from the same lab
Who was studied: 341 mothers in Japan reporting on children in grades 1 to 3. Average child age was about 8.
What they found: Children whose longest focus and favorite play were online scored far higher on boredom tendency. They scored lower on focus tendency. Attention difficulties also ran higher in the online groups. Mothers who got bored easily had children who leaned online too.
What it means for you: "He concentrates longest on a screen" reads as a boredom signal to us. That profile gets fast starting, high energy missions. We do not claim screens cause the boredom, or boredom causes the screens. This study cannot say which way it runs.
43Moderate
Boredom-prone kids hate waiting. The wait itself is part of why focus slips.
Hsu, Chen, Ni, Chueh & Eastwood (2025), Frontiers in Psychiatry 16:1526089.
Moderate: two informants, a clinical comparison group, validated scales; but a clinical sample, correlational mediation, and most of the age range sits above the band
Who was studied: 183 young people, ages 9 to 16, in Taiwan. Half had ADHD. Half did not. Only ages 9 to 10 sit inside our band.
What they found: The ADHD group scored higher on boredom and on hating delay. Boredom, delay hatred, and inattention all moved together. In parent ratings, hating delay carried part of the path from boredom to inattention.
What it means for you: For a boredom-prone child, missions start fast and pay off early. No long build-up before anything happens. Waiting time inside a mission gets filled, not left empty. This was a clinic sample, so no pack language ever screens for or treats attention problems.
44Thin
Some kids are bored everywhere. Homework was the worst spot of all.
Larson & Richards (1991), American Journal of Education 99(4) (article title: "Boredom in the middle school years: Blaming schools vs blaming students").
Thin (for this product): foundational and still the reference point for trait boredom in youth, but above the band, three decades old, and entered here on a secondary summary pending re-check
Who was studied: Students in grades 5 to 9, paged at random moments for one week. Mostly above our band. This entry rests on a later summary, not the original paper.
What they found: The same students reported boredom at school and away from school. Boredom looks like a trait the child carries, not just an answer to one dull setting. Homework and schoolwork drew the most boredom, about 40 percent of reports. Even creative activities drew about 30 percent.
What it means for you: When a parent says "he is bored everywhere," we believe it is information about the child. Good activities will still meet boredom sometimes, creative ones included. We do not quote these percentages as facts about 5 to 10 year olds. The original paper needs a fresh check first.
45Moderate
Interest alone does not make a young child stick. Self control has to come with it.
Torgrimson, Tan & Grammer (2021), Journal of Experimental Child Psychology 208, 105141.
Moderate: in-band, a behavioral persistence measure, and a clean moderation pattern, but one small single-site sample
Who was studied: 73 children, average age about 7, working on a hard puzzle task.
What they found: Interest and feeling able turned into sticking power only in children with fair to strong impulse control. Children low on impulse control quit sooner at the same interest level. Girls stuck longer than boys at equal motivation.
What it means for you: For ages 5 to 7, sticking power is built into the task shape. One clear thread. A visible next step. Nothing else competing for the eyes. A child who quits was not necessarily bored. Interest was there in the quitters too.
46Moderate
How long a 9-year-old sticks at a hopeless puzzle tracks his childhood, not just his grit.
Whipple, Genero & Evans (2016), Journal of Applied Research on Children 7(1), Article 4.
Moderate: in-band behavioral measure and a longitudinal design, but a mostly white rural sample, and statistical mediation is not causal proof
Who was studied: 206 children in rural New York, followed from birth to age 23. Sticking power was timed at ages 9 and 13 on a puzzle that could not be solved.
What they found: The more of childhood a child spent in poverty, the less time he stuck at the puzzle. Sticking time then carried part of poverty's link to school confidence at 17 and to education level at 23. The sample was mostly white and rural. Numbers like these show a pathway. They do not prove cause.
What it means for you: A quitting point tells us about fit and load. It never earns a child a label. Hard missions build in early wins, so sticking gets practiced instead of just demanded.
47Thin
For 7 to 9 year olds, challenge and complexity pull kids in more than feedback does.
Inal & Cagiltay (2007), British Journal of Educational Technology 38(3), 455 to 464.
Thin to Moderate: directly in band and in a play context, but a small single-site sample and an interview measure adapted on the fly; no experience sampling study of flow exists in this age band (see empty results below)
Who was studied: 33 children, ages 7 to 9. They played games one hour a week for six weeks and were interviewed about feeling absorbed.
What they found: The children did report deep absorption. Challenge and complexity drove it most. Clear feedback mattered less. Game mechanics weighed more for boys and the story frame more for girls, but those groups were tiny. Some flow questions had to be dropped because children this age could not grasp them.
What it means for you: When a mission is not holding a 7 to 9 year old, we turn the difficulty and complexity dials first. Clear feedback is basic upkeep, not the draw. This study shows which way the lever points. It does not find the perfect setting.
48Moderate
The fun sits in solving something hard. Repeating a solved one drains it.
Harter (1974), Child Development 45, 661 to 669.
Moderate: direct behavioral affect measurement on the difficulty question, discounted for age position and a single paradigm from 1974
Who was studied: Children in grades 5 and 6, ages about 10 to 12. At and above the top of our band. They worked word puzzles of rising difficulty.
What they found: Children smiled more on puzzles they solved than on ones they failed. Among solved puzzles, the harder the puzzle, the bigger the smile. Repeating a puzzle already solved made the smiling fade.
What it means for you: Missions climb in difficulty while success stays in reach. A mastered mission gets retired, not repeated as filler. Easy wins alone do not hold children. This study measured that directly.
49Strong
Play is essential to healthy development.
Ginsburg (2007), Pediatrics 119(1), 182 to 191; American Academy of Pediatrics clinical report.
Strong (as consensus): official AAP clinical report; the grade applies to the consensus claim, not to any measured effect size (none is offered)
Who was studied: A report from the American Academy of Pediatrics. It sums up the research on kids of all ages.
What they found: Play helps kids grow in body, mind, and friendships. The report warns that play time is being squeezed out by busy schedules and less recess.
What it means for you: We treat play as a real need. It earns a protected spot in the day.
50Moderate
Guided play beat lessons on some skills.
Skene, O'Farrelly et al. (2022), Child Development 93(4), 1162 to 1180.
Moderate: genuine meta-analysis with positive effects, but effects are outcome-specific, heterogeneous, and concentrated in under-8s
Who was studied: 39 studies with about 3,900 kids, ages 1 to 8.
What they found: Kids in guided play did better than kids in direct lessons at early math, shapes, and switching tasks. They beat free play at space words. On most other skills there was no clear winner.
What it means for you: A pack can teach a little without turning into school. We claim the few wins the studies found. Nothing more.
51Strong
Pretend play is good. It is not magic.
Lillard, Lerner, Hopkins, Dore, Smith & Palmquist (2013), Psychological Bulletin 139(1), 1 to 34.
Strong (as a critique): comprehensive, methodologically careful review in the field's flagship review journal; it remains the standard caution
Who was studied: A big review of the pretend play studies. Most kids in them were preschool age.
What they found: The review found no strong proof that pretend play alone builds any one skill. For talking, stories, and feelings, other paths work just as well.
What it means for you: Packs use pretend play because kids love it. We never sell it as the one way a skill grows.
52Moderate
Kids with more free, unstructured time run their own minds better.
Barker et al. (2014), Frontiers in Psychology
Moderate (§5, item 7)
Who was studied: Six-year-olds. Researchers tracked how their weeks were spent.
What they found: Children whose weeks held more loosely structured time did better at directing their own thinking. They set their own goals and kept at them. The link showed up in how the week was filled, not in lessons.
What it means for you: A pack lights the spark and then gets out of the way. We do not fill every minute with directions.
53Moderate
Hearing the same story again and again is how toddlers learned the words.
Horst, Parsons & Bryan (2011), Frontiers in Psychology 2:17. (Same study as BLD-09, filed there for word learning; filed here for repetition and re-play value.)
Moderate: clean exposure control, but N=16 and age 3
Who was studied: 16 children, all age 3. Below our band.
What they found: One group heard the same stories three times in a week. The other group heard different stories with the same new words in them. Only the same-story group learned the words. They still knew them a week later.
What it means for you: A favorite mission is built to be replayed word for word. Same frame each time frees the child's mind to notice new detail. New is not always better.
54Strong
Working together beat rivalry and solo work on results. Rivalry and solo tied.
Johnson, Maruyama, Johnson, Nelson & Skon (1981), Psychological Bulletin 89(1), 47 to 62.
Strong for the achievement ordering (the anchor meta-analysis of the goal-structure literature); indirect for this product, because the outcome is school task achievement, not holding time in play
Who was studied: A review of 122 North American studies across school ages. The outcomes were school results and output, not play time.
What they found: Children working toward a shared goal did far better than children competing head to head. They also beat children working alone. Teams competing against other teams did well too. Head to head rivalry and working alone came out the same.
What it means for you: Partner and group missions default to a shared goal. Teams against the game is the allowed form of rivalry. This is school results evidence, so we borrow the shape, not a play promise.
55Strong
Every named teamwork method beat rivalry and solo work in class.
Johnson, Johnson & Stanne (2000), Cooperative Learning Methods: A Meta-Analysis, University of Minnesota monograph.
Strong as a synthesis of named methods; achievement outcome in classroom settings, so indirect for play engagement
Who was studied: A review of 164 school studies, from preschool to college. Eight named teamwork methods were tested.
What they found: All eight methods beat competitive and solo setups on school results. One method, Learning Together, won by the widest margin. Rivalry and solo work were again a near tie.
What it means for you: Group missions use real structure. Roles. A team goal. A team contest now and then. Just putting kids in a group is not teamwork, and this review only tested the structured kind.
56Moderate
For young teens, teamwork linked to both better results and better friendships.
Roseth, Johnson & Johnson (2008), Psychological Bulletin 134(2), 223 to 246.
Moderate as a synthesis; Thin for this product by age. It is the only goal-structure synthesis that measures peer relationships as an outcome, and its sample sits entirely above the band
Who was studied: A review of 148 studies with over 17,000 early teens, ages 12 to 15, in 11 countries. Entirely above our band.
What they found: Teamwork setups came with higher achievement and warmer peer relationships than rivalry or solo setups. Under teamwork the two fed each other. Doing well and getting along rose together.
What it means for you: Partner missions are more than task shapes. They build the relationship too. That claim is borrowed from teen data, and we label it as such. The in-band anchors are the four studies above this one.
57Strong
Play with a light goal often beats lessons and free play alike.
Weisberg, Hirsh-Pasek & Golinkoff (2013); Hirsh-Pasek et al. (2022) synthesis
Strong (§5, item 1)
Who was studied: The playful learning research as a whole. No single sample.
What they found: Guided play often did better than direct teaching. It often did better than free play with no goal at all. In guided play the adult sets up a goal. The child stays in charge of the play.
What it means for you: That is the shape of every pack. We bring the frame and the goal. Your kid brings the play.
58Moderate
Planned pretend play with roles builds focus and self control.
Diamond et al. (2007), Science (Tools of the Mind RCT)
Moderate, with a replication caveat (§5, item 2)
Who was studied: Preschoolers in a real test of the Tools of the Mind program.
What they found: Kids in the program held their focus far better on hard tasks. On the hardest attention tests they scored 84 percent against 65 percent. Later and bigger tests of the full program gave mixed results. One big review found no clear effect on spoken language.
What it means for you: Packs use pretend play with roles and rules a child has to stay inside. We call it a tested way to play. We never call the program proven as a whole.
59Moderate
Movement games with growing rules helped in one country. They did not in another.
Tominey & McClelland (2011) program; New Zealand cluster RCT; Kenyan cluster RCT
Mixed (§5, item 3)
Who was studied: 212 four year olds in New Zealand. And 451 children in Kenya.
What they found: In New Zealand the games improved flexible thinking and attention. Teachers rated self control higher four months later. In Kenya the same kind of games showed no effect.
What it means for you: Packs can use movement games with rules that grow. The mixed proof travels with the claim. We never promise these games boost every child's thinking.
60Strong
A board game with numbered squares builds early number sense.
Ramani & Siegler (2008), Child Development; Laski & Siegler (2014)
Strong (§5, item 4)
Who was studied: Preschoolers from low income homes. Later work stretched the board to 100 with six year olds.
What they found: About one hour of play in total made kids better at comparing sizes. They placed numbers on a line more accurately. They counted better and knew numerals better. The gains were still there nine weeks later. The same game with colored squares and no numbers gave no gains at all. Counting on from the square your piece sits on was the part that did the work.
What it means for you: Number games in packs use numbered squares and ask the child to count on. Short sessions that add up to about an hour are the dose that worked.
61Moderate to strong
Building and puzzle play build space skills. Space skills point toward later math.
Verdine et al. (2014); Bower et al. (2025), Developmental Psychology
Moderate to strong (§5, item 5)
Who was studied: Three year olds in one study. 331 children in the second.
What they found: Copying block models at age 3 tracked early math. Space skill at 3 predicted math at 5 better than early counting did. Five weeks of puzzle practice improved puzzle building. Talking about shapes during play added word problem gains. The jump to math overall was weak.
What it means for you: Packs use build to the model tasks and puzzle tasks. The words for shapes get said out loud during play. We never claim this play lifts math across the board.
62Background
Puzzle play at home in the toddler years points to later space skill.
Levine et al. (2012)
Cited within a moderate-to-strong item (§5, item 5); no separate grade in brief
Who was studied: Toddlers at home. Play was watched between 26 and 46 months. Skill was tested at 54 months.
What they found: Kids who played with puzzles more at home did better later at turning shapes in their heads.
What it means for you: Plain puzzle play at home is a real path to space skill. It starts early and it costs nothing fancy. One study carries this claim, so we hold it at that weight.
63Strong
Reading together with questions builds the words kids can say.
Mol, Bus, de Jong & Smeets (2008), meta-analysis of 16 studies
Strong at ages 2 to 3, weaker after (§5, item 6)
Who was studied: Kids ages 2 to 5 across 16 studies.
What they found: Reading where the adult asks and the child answers gave a clear gain in the words children can say. The gain was strong at ages 2 to 3. It shrank a lot at ages 4 to 5.
What it means for you: Story packs ask the child questions back. We size the claim to the young ages where it is strong. We do not promise the same word gains at ages 5 to 10.
64Background
Spotting patterns early is one of the strongest signs of later math success.
Vanderbilt longitudinal study (reported by the Society for Research in Child Development, Child Development); Papic et al. (2011)
Documented in brief (§8); no §5-scale grade assigned
Who was studied: 517 children. They were followed from preschool to the end of fifth grade.
What they found: Pattern skill in preschool sat among the top predictors of math in fifth grade. It ranked with counting and comparing amounts. Teaching pattern work also improved later counting and sums.
What it means for you: Patterns, sequences, and codes are a real math path in packs. They are not decoration.
65Background
Kids learn words better from the same story read again.
Horst, Parsons & Bryan (2011), Frontiers in Psychology
Not graded in brief; cited in §13 for pack scope
Who was studied: Young children in a word learning study. The list of studies does not name the sample size.
What they found: Hearing the same stories more than once taught words better than hearing new stories each time.
What it means for you: Packs replay missions on purpose. Playing the same one several times is the design. New every time is not better here.
66Strong
Feeling able to do it drives kids most.
Bureau, Howard, Chong & Guay (2022), Review of Educational Research 92(1), 46 to 72.
Strong (for the association): large meta-analysis testing the theory's core pathways simultaneously
Who was studied: A review of 144 studies with more than 79,000 students.
What they found: When adults back a kid's choices, kids want to keep going. The biggest driver was feeling able. Choice came next. Feeling close came third.
What it means for you: Packs include wins a kid can see. You get three simple moves too. Hear the feeling. Say why it matters. Offer real choices.
67Moderate
A story that ends on a cliffhanger brings kids back. One-off episodes fade.
Lu, Green, Sousa, Hwang, Lee, Thompson & Baranowski, Communication Research 52(5), 600 to 625 (online 2023).
Moderate: RCT, in-range, but small N and a video-game context
Who was studied: 44 children, ages 8 to 12, in a randomized study with repeated visits.
What they found: Children who got a serial story with cliffhangers moved more and played longer across visits. Children who got finished one-off episodes played less and less. Oddly, the two groups said they felt equally pulled into the story.
What it means for you: Missions link into arcs with a reason to return tomorrow. We watch what kids do, not just what they say was fun. And no study has mapped the perfect difficulty climb for paper games. We say that plainly.
68Thin
Kids come back to unfinished tasks. That part is solid. The memory claim is not.
Zeigarnik (1927), Psychologische Forschung 9, 1 to 85 (with Ovsiankina 1928).
Thin: foundational and famous, but 1927 methods and secondary sourcing
Who was studied: 138 children in the original 1927 experiments.
What they found: More than 80 percent of children went back to a task left unfinished. Only 6 percent went back to a finished one. The old claim said unfinished tasks are also remembered better. A 2025 review of the whole record cut that memory claim down. The coming back part held up. About two times in three, people return.
What it means for you: Missions can pause in the middle and wait. An unfinished mission on the table is an invitation. We never claim leaving one open makes your child remember it better.
69Thin
People push harder toward whichever end of a goal looks smaller.
Koo & Fishbach (2012), Journal of Consumer Research 39 (Oct 2012), "The Small-Area Hypothesis."
Thin (for this product): adult consumer studies, mechanism plausible but untested in 5 to 10s
Who was studied: Adults. No children took part.
What they found: Early in a goal, people work harder when shown the progress already made. It looks small and fast. Near the end, they work harder when shown the little bit left. Motivation followed whichever side was smaller.
What it means for you: Progress on a pack flips its message as a set nears the end. First it counts what is done. Then it counts what is left. This comes from adults, so we use it as a light touch.
70Strong
"You are so smart" backfires. "You kept trying" works.
Mueller & Dweck (1998), Journal of Personality and Social Psychology 75(1), 33 to 52 (PMID 9686450).
Strong (finding): replicated pattern, in-range; citation link tier ⚠️ (canonical page not opened in this harvest)
Who was studied: Six studies. The first had 128 fifth graders, ages 10 to 12.
What they found: Children praised for being smart picked easier problems afterward. After a failure they gave up sooner, enjoyed it less, and blamed low ability. Some even lied about their scores. Children praised for effort picked harder problems and hunted for better strategies.
What it means for you: Cards praise effort and strategy in plain words. "You kept trying different ways." Never "you are so smart."
71Moderate
A promised prize cut later play in half. A surprise prize did not.
Lepper, Greene & Nisbett (1973), Journal of Personality and Social Psychology 28(1), 129 to 137.
Moderate: classic, but old, small, and exact N unconfirmed
Who was studied: Preschoolers who already loved drawing.
What they found: Children promised a "Good Player Award" for drawing later spent about half as much free time drawing. Children who got the same award as a surprise drew as much as ever. Only the expected reward did the damage.
What it means for you: Bonuses arrive as surprises. No card ever says "finish this and earn that."
72Strong
Across 128 experiments, prizes undercut free choice. Praise lifted it.
Deci, Koestner & Ryan (1999), Psychological Bulletin 125(6), 627 to 668.
Strong: large meta-analysis, child-relevant pattern, with a noted counter-meta-analysis
Who was studied: A review of 128 experiments. The prize effect hit children harder than college students.
What they found: Every kind of expected prize lowered children's later interest when the choice was theirs. The drop was real and steady. Warm and specific feedback raised it. One rival review reached a softer verdict, and that dispute is real. We do not hide it.
What it means for you: Feedback on cards talks about the work itself. There is no prize ladder at the center of a pack.
73Moderate
Head to head rivalry made kids ask "was I smart?" Solo goals made them ask "how do I do this?"
Ames (1984), Journal of Educational Psychology 76(3), 478 to 487.
Moderate: a single in-band experiment with a small N and one task type, but the manipulation is the exact variable and the mechanism (attributions) is measured directly
Who was studied: 88 children in grades 5 and 6, working on a new puzzle task.
What they found: Children in the rivalry setup blamed or credited their ability. Children set against their own mark credited effort instead. They talked themselves through the task and watched their own progress. How a child explained the result also drove how he felt about it.
What it means for you: Hard missions default to "beat your own last mark." That frame protects the will to keep trying. We keep head to head framing away from a child who just failed.
74Thin
A partner in either role raised interest. Teammates most wanted to play again.
Plass, O'Keefe, Homer, Case, Hayward, Stein & Perlin (2013), Journal of Educational Psychology 105(4), 1050 to 1066.
Thin for this product: a clean experiment and the only head-to-head here on enjoyment and replay intention, but above band, small N, and a single screen game
Who was studied: 58 middle school students. Above our age band. They played a math video game alone, against a rival, or with a teammate.
What they found: Rivalry raised in-game learning over solo play. Both rivalry and teamwork raised interest and enjoyment. Playing as a team lowered scores during the session itself. But teammates most wanted to play again and to recommend the game. Skill outside the game rose for everyone and did not differ by setup.
What it means for you: A partner, rival or teammate, is a real interest lever. We claim that at hint strength for our ages, since these were older kids and one screen game. The classroom reviews above point the other way on rivalry and results, and we follow them for results.
75Thin
Team games made older kids feel closer and more able. "More fun" barely showed.
Engels & Freund (2020), PLoS ONE 15(12), e0243608.
Thin for this product: above band, small effects, and the headline enjoyment effect did not reach significance; entered because it is a rare direct cooperative versus competitive games test with enjoyment as the outcome
Who was studied: 285 students, ages 10 to 16, in German gym classes. Only the youngest edge touches our band.
What they found: Cooperative games raised feelings of closeness and of being able. The enjoyment edge was small and did not quite reach the bar for counting as proven. The good feelings about closeness and ability carried part of that small edge.
What it means for you: Team framing in movement missions is a fair bet for closeness and confidence. We hold it at hint strength. We never print "team games are more fun" as a flat fact.
76Strong
Choice makes kids try harder. Two to four choices in a row work best.
Patall, Cooper & Robinson (2008), Psychological Bulletin 134(2), 270 to 300.
Strong (for the choice effect in children): a 41-study meta-analysis in the field's top review journal, with the child advantage tested rather than assumed; most underlying child studies are short lab or classroom tasks
Who was studied: A review of 41 experiments with children and adults. The researchers tested age head on.
What they found: Choice raised motivation, effort, results, and feeling able. The lift was bigger for children than for adults. Small side choices counted as much as big ones. Two to four choices in a row worked best. A reward handed over after the choice weakened the effect.
What it means for you: Missions hold small real choices. Which object. Which order. Which door. Even looks-only choices are worth building. We never pair a choice with a promised prize, and we never stack more than four choices in a row.
77Moderate
"You will be tested on this" killed interest. The same lesson without pressure did not.
Grolnick & Ryan (1987), Journal of Personality and Social Psychology 52(5), 890 to 898.
Moderate: a single in-band experiment at the top of the band, small N, but a direct manipulation of framing with a follow-up, and consistent with HOLD-46 at the band's lower end
Who was studied: 91 fifth graders, about ages 10 to 11.
What they found: Both taught groups memorized more than the left-alone group. The pressure group felt squeezed and lost interest. Their memorized facts also faded faster over eight days. The no-pressure taught group learned the ideas just as well and kept their interest.
What it means for you: No card carries test, grade, or checking language. Structure is fine. Pressure is the poison, and this study pinned it down.
78Moderate
The words of a rule do the damage. The rule itself does not.
Koestner, Ryan, Bernieri & Holt (1984), Journal of Personality 52(3), 233 to 248.
Moderate: one small experiment, but in-band, a direct wording manipulation, and the cleanest available evidence that the wording of a rule, not the rule itself, does the damage
Who was studied: 44 children in grades 1 and 2, about ages 6 to 8, doing a painting activity.
What they found: Limits stated as orders ("you have to," "be a good boy or girl") cut motivation, enjoyment, and creativity. The paintings scored worse too. The same limits stated as plain facts about the materials did no harm at all. They matched having no limits.
What it means for you: Pack rules are written as facts. "The small sheet is yours. The big sheet stays clean." Never as obedience demands. Every printed instruction gets checked for pressure wording.
79Moderate
Who picks matters. Some kids light up when a trusted person picks for them.
Iyengar & Lepper (1999), Journal of Personality and Social Psychology 76(3), 349 to 366.
Moderate: two experiments, in-band, yoked designs so the activities themselves were identical across conditions; the moderator is cultural background in one US metropolitan sample, so the size of the effect in any given family is unknown
Who was studied: Two studies. 105 children in grades 3 to 5, then 88 fifth graders. Anglo American and Asian American families.
What they found: Anglo American children did best and stayed longest when they picked themselves. They did worst when others picked. Asian American children showed the mirror image. They did best when their mother or their classmates had picked. The activities were identical either way. Only the picker changed.
What it means for you: "Peg picked this for you" stands beside "you pick" as an equal door into a pack. We ask families who should choose. We never claim picking it yourself is the only route that works.
80Moderate
For kids who resist, a choice of task or order cut problem behavior.
Shogren, Faggella-Luby, Bae & Wehmeyer (2004), Journal of Positive Behavior Interventions 6(4), 228 to 237.
Moderate: a real meta-analysis of the closest population to the reactant use case (children who can do the task but will not), but single-case designs, a weak effect metric, mixed ages, and disability samples in mostly school settings
Who was studied: A review of 13 small studies with 30 participants. All had disabilities. Children and adults, including school age students.
What they found: Offering a choice of activity, or of the order to do tasks in, cut problem behavior by amounts doctors call meaningful. Results ranged widely from child to child. Some hit zero problem behavior often. Others barely moved.
What it means for you: A child who will not start gets to pick the mission order first. That is our standard move. These were disability studies in schools, so we never quote these numbers for a typical child at home.
81Thin
Pushy control breeds pushback. The chain is measured. In teens.
Van Petegem, Soenens, Vansteenkiste & Beyers (2015), Child Development 86(3), 903 to 918.
Thin (for this product): the mechanism evidence is strong in design (four studies, clinical and community samples, a vignette experiment) but every sample is 12 or older; it anchors the mechanism, it cannot size the effect at 5 to 10
Who was studied: Four studies with 1,472 young people, ages 12 to 21. Above our band.
What they found: Controlling parenting came first. Then came the felt pressure of the young person. Then came defiance and acting out. Warmth and clear rules did not explain it away. Control itself carried the effect.
What it means for you: When a child defies a pushy instruction, we read it as a predictable answer to pressure. It is not a character flaw. Parent scripts strip the pressure out and keep the rules. Nobody has sized this effect at ages 5 to 10, and we say so.
82Strong
Stick-with-it behavior can be taught. Kids then pick the hard task and retry after failing.
Alan, Boneva & Ertac (2019), Quarterly Journal of Economics 134(3), 1121 to 1162.
Strong for malleability and difficulty choice in band: two RCTs, a behavioral incentivized measure, effects replicating across samples; school context and a disadvantaged urban sample bound the claim
Who was studied: Over 3,200 fourth graders, ages 8 to 10, in 52 schools in poorer parts of Istanbul. Two separate randomized trials.
What they found: Teachers taught a short course on effort and setbacks. Taught children picked the harder task more often. They retried more after a failure message. They succeeded 8 to 10 points more often and earned 16 to 26 percent higher rewards. Math scores rose and still showed a gain two and a half years later.
What it means for you: Missions coach the retry out loud. A failed first try is a normal scripted step, with a visible second try after it. Harder levels carry a real payoff difference. We never promise a pack builds lifelong grit as a trait. This study changed behavior inside a taught classroom, which is a smaller and truer claim.
83Strong
Unfinished tasks are not remembered better. People do go back to them.
Ghibellini & Meier (2025), Humanities and Social Sciences Communications 12, article 962.
Strong (as a correction): the definitive synthesis of this literature, and it reverses the memory half of an existing entry in the list of studies
Who was studied: A review of 59 published studies. Most used adults. Child studies sit inside the return-to-task pool, and their numbers cannot be split out.
What they found: Across the record, interrupted tasks were remembered no better than finished ones. The famous memory effect failed. The return effect held firm. People resumed an interrupted task about 67 percent of the time, and more often when the task was attractive.
What it means for you: This review corrects the old entry on unfinished tasks. Pause points and a visible half-done mission earn their place because kids come back, not because kids remember. No card will ever claim an open mission stays in a child's memory.
84Moderate
"This will be graded" made kids pick easy puzzles and enjoy them less.
Harter (1978), Child Development 49(3), 788 to 799.
Moderate: a clean experimental contrast on the exact behavior PGP cares about (chosen difficulty), discounted for the above-band sample and 1978 vintage
Who was studied: Sixth graders, ages about 11 to 12. Just above our band.
What they found: Children chose how hard their word puzzles would be. The group told their work would be graded picked easier puzzles. They also smiled less after solving. The group told it was a game picked harder ones. Each group knew it would have chosen the other way under the other framing.
What it means for you: Scores, streaks, and grades stay off the child's side of a pack. Difficulty is offered as a game choice. A child should never be able to fail in public at a level he picked.
85Strong
After failure, kids split two ways. One group blames itself. The other hunts for a fix.
Diener & Dweck (1978), Journal of Personality and Social Psychology 36(5), 451 to 462
Strong for the existence of the two patterns at the top of the band: direct continuous observation across two studies; discounted because the sample sits at age 10 to 11 and the paradigm is a laboratory discrimination task
Who was studied: 130 fifth graders, about ages 10 to 11. Researchers sorted them first into helpless and mastery-minded groups, then listened to everything they said aloud.
What they found: Before failure the two groups performed the same. After failure the helpless group blamed low ability and felt worse. Their strategies got worse and worse. The mastery group barely blamed anything. They talked themselves through checks and fixes, and their strategies held or improved.
What it means for you: Cards carry a next step prompt after any fail point. Failure is framed as news about the attempt, never about the child. Parents can watch which pattern their child shows. Does he give up and blame himself, or regroup and retry? So we may ask about it as behavior. Never call a mission "for smart kids" near a fail point. The groups were equal before failure, so a helpless answer is not low ability.
86Moderate
Shielding a failure-shy child with easy wins did not repair anything. Failing safely with coaching did.
Dweck (1975), Journal of Personality and Social Psychology 31(4), 674 to 685
Moderate: a genuine experiment on exactly the target behavior, but N of 12 and from 1975; treat as design direction, not an effect size
Who was studied: 12 children, ages 8 to 13, picked out by school staff for extreme reactions to failure. A tiny sample, and it reaches above our band.
What they found: One group got success-only practice. After training they still fell apart at failure. The other group got real failure inside training, plus coaching to blame effort instead. That group held or improved after failure and changed how they explained it.
What it means for you: Packs may hold survivable failure points on purpose, with effort and strategy words built in. A child who melts down at failure does not get an all-wins pack. And we stay humble here. The repair training was intensive and led by an adult. Words on a card alone are not that training.
87Background
Kids stick with play that gives them choice, progress, and people.
Deci & Ryan; Ryan & Deci (2000) (self-determination theory)
The most replicated motivation framework available (§7)
Who was studied: The motivation research as a whole. No single sample.
What they found: Children stay engaged when three things are fed. They get to choose. They feel themselves getting better. They feel close to the people with them.
What it means for you: Every mission is built for those three. Choice. A win the child can feel. Someone to share it with.
88Background
Promising a prize for play a child already loves can kill the love.
Deci, Koestner & Ryan (1999), meta-analysis of 128 experiments
Meta-analytic (§7; §5-scale grade not assigned)
Who was studied: 128 experiments pulled together in one review.
What they found: A promised prize a child can hold made the play less fun for its own sake. Praise that tells a child what they did well helped instead.
What it means for you: Packs never pay a child to play, in coins or points or prizes. Praise names what the child did. That is the only reward on offer.
89Background
Collecting pulls hard. A surprise reward pulls hardest of all.
Literature as summarized in brief (§8); no single study named
"Powerful, well-studied psychology" (§8); no §5-scale grade assigned
Who was studied: No single study. This entry sums up a body of writing on why kids collect.
What they found: A reward a child cannot predict keeps the chase alive longer than a fixed one. Finishing a set pulls too. So does rarity. So does showing the set to friends. The Pokemon card boom ran on all four.
What it means for you: Sets and rarity live inside the play, where a child earns them and can see them. That same engine never touches the buying. See NEG-02 for the hard line.
90Moderate
Interest develops in phases, from a spark to something a child seeks out.
Hidi & Renninger (2006), Educational Psychologist
Moderate as a design framework; it is not a finding with an effect size, and no pack cites it as one
Who was studied: A framework paper synthesizing the interest literature, mostly school learners.
What they found: Four phases: triggered situational interest, maintained situational interest, emerging individual interest, and well-developed individual interest. A designed product can act on the first two phases: novelty, surprise, and personal relevance, then content worth staying with. The later phases require the child's own re-engagement.
What it means for you: The first pack in a series is designed to trigger, and the series to maintain: returning characters, growing worlds, rising stakes. Success is judged by voluntary re-engagement, not by one session's excitement.
91Studied in grown-ups
Adults waiting for an experience enjoy the wait more than adults waiting for a thing.
Kumar, Killingsworth & Gilovich (2014), Psychological Science
Moderate for adults, across four converging studies; thin for this product, because no study measures anticipation in 5 to 10 year olds
Who was studied: Adults throughout: 97 university students in the first study, experience sampling with 2,266 adults in the second, four studies in total.
What they found: Waiting for an experiential purchase was rated more pleasant and more exciting, with more excitement and less impatience, than waiting for a material purchase, across questionnaires about real planned purchases, experience sampling, and an archival study of people in queues. The savoring account behind it holds that anticipating a future good carries its own pleasure.
What it means for you: Anticipation devices in multi-day arcs are a labeled design bet: a sealed final envelope shown on day 1 and opened on the last day, or a covered picture revealed piece by piece. We never cite anticipation research as child evidence in print.
92Moderate
Looking out the car window helps some kids. It does not stop carsickness for all.
Schmidt et al. (2020), Transportation Research Part F 71, 76 to 87.
Moderate: huge N, but adult retrospective survey
Who was studied: 4,479 adults in five countries. They looked back on their own sickness, childhood included. Adults, not kids in car seats today.
What they found: Nearly half had been carsick in the past five years. For many, looking down was part of getting sick. But more than half of sufferers got sick even while looking out the whole time.
What it means for you: Car packs lean on looking out and listening. We never promise a window game will stop a sick kid from feeling sick.
93Thin
Eyes down in a car made sickness worse. Listening did not.
Metzulat et al. (on-road study, Zenodo preprint).
Thin: preprint, small adult N, but mechanism-consistent with SCN-01
Who was studied: 20 adults who get carsick easily. Each one took three drives. One drive was a listening task. Two were tablet tasks with eyes down.
What they found: Both tablet tasks brought on more sickness than the listening task. Moving pictures on the tablet were the worst of all. This is one small early study. It is not yet fully checked by other scientists.
What it means for you: Car packs start with the ears. Looking games stay short and send eyes back up and out.
94Moderate
A kids podcast got every family talking in the car.
Grack Nelson, Tsakakis & Christian Ronning (2026), Frontiers in Communication 11:1725515 (Brains On!).
Moderate: qualitative, but 32/32 families and a car-specific mechanism
Who was studied: 32 families who listened to a kids podcast in their vehicle. Four families were then studied up close.
What they found: The podcast sparked talk in all 32 families. The closed car helped everyone focus on the same thing. Parents and kids caught each other's eyes in the rearview mirror. Most kid podcast listening happens in cars anyway.
What it means for you: A car story can carry a whole ride. Packs use call and response so the story turns into talk, not just noise.
95Thin
Parents say audio stories help. That is parent opinion, not proof.
Moisi, Clark & Arif (2026), National Literacy Trust report "Growing up listening."
Thin: report, parent report, below-range ages
Who was studied: 3,194 UK parents of kids ages 0 to 5. Younger than our band.
What they found: Parents said listening helped focus, new words, and imagination. About a quarter of listening happened on trips. The report itself warns there is no proof listening builds reading skill.
What it means for you: Parents already trust the car story format. We use it gladly. We never claim it teaches your kid to read.
96Thin
A smoother car ride made reading in the car easier.
DiZio et al. (2018), Aerospace Medicine and Human Performance 89(9), 822 to 829.
Thin: mechanism support, not a child product test
Who was studied: Adults in a lab style test. No kids and no real product were tested.
What they found: Special suspension cut the clash between what eyes see and what the body feels. Reading then felt better and made more sense.
What it means for you: This one only backs the idea behind the car entries above. It gives us nothing to promise you. It backs no claim for any product.
97Moderate
Waiting works when the mind goes somewhere fun.
Mischel, Ebbesen & Zeiss (1972), Journal of Personality and Social Psychology (marshmallow paradigm).
Moderate: foundational, but below-range and old
Who was studied: Preschoolers, ages 3 to 5, in the famous marshmallow studies. Younger than our band. One test used 50 kids per group.
What they found: With treats in sight, kids waited about 3 minutes. With fun thoughts to play with, they waited over 8 minutes. One setup reached about 13 minutes. With nothing to think about, they lasted under a minute.
What it means for you: Waiting packs fill the wait with silly thoughts and small games. They never just tell a kid to be patient.
98Strong
Kids wait far longer for adults who keep their word.
Kidd, Palmeri & Aslin (2013), Cognition 126(1), 109 to 114.
Strong: experimental, large effect, but small N and just below range
Who was studied: 28 kids, about age 4 and a half. Just below our band.
What they found: Kids with a reliable adult waited about 12 minutes. Kids whose adult had broken a promise waited about 3. Nine of 14 in the first group waited the full 15 minutes. Only 1 of 14 did in the second.
What it means for you: A waiting pack always pays off what it promises. If the card says a reward comes, the reward comes.
99Strong
The marshmallow test predicts less than you have heard.
Watts, Duncan & Quan (2018), Psychological Science 29(7), 1159 to 1177.
Strong: large conceptual replication; this is the corrective entry
Who was studied: 918 kids. They did the waiting task at age 4 and a half. Researchers checked their lives again at 15.
What they found: The link between waiting and later school success was about half the size first reported. Once family background and early skills were counted, it shrank by two thirds more.
What it means for you: Waiting games are for comfort in the moment. They are never a test of your kid's character or future.
100Moderate
A good distraction calms a waiting room.
Pati & Nanda (2011), Health Environments Research & Design Journal 4(3), 124 to 140. DOI 10.1177/193758671100400310.
Moderate: clinic setting, in-range-adjacent, but attention-capture is the mechanism, not a screen endorsement
Who was studied: 158 young patients, ages 5 and up, at dental and heart clinics. Researchers watched them over 12 days.
What they found: Screens showing pleasant content grabbed kids' attention and held it. Kids stayed calmer and moved less. The content pulled eyes away from people, books, and toys.
What it means for you: The trick is grabbing attention, not the screen itself. A waiting card is built to grab it just as fully.
101Moderate
Shared fun calmed waiting kids. A nature video did the opposite.
Biddiss, Knibbe, Fehlings, McKeever & McPherson (2019), Developmental Neurorehabilitation 22(7), 445 to 452.
Moderate: in-range-adjacent, clinical sample, but a direct waiting-space test with a negative result included
Who was studied: 271 young people, ages 5 to 19, with developmental conditions. They waited in a rehab clinic space.
What they found: Kids picked shared distractions over their own things. Hands on media and a fish tank lowered worry. A nature video raised worry. Kids' own devices did not lower it.
What it means for you: Waiting packs are shared and hands on, not solo screen time. And we never assume pretty nature pictures calm every kid.
102Moderate
Kids who struggle with waiting struggle everywhere. Culture does not change that.
Chan, Shum, Downs, Liu & Sonuga-Barke (2025), European Child & Adolescent Psychiatry 34(2), 633 to 645.
Moderate: cross-cultural, but preschool and correlational
Who was studied: 112 preschoolers in Hong Kong and the UK. Mean age just under 4. Below our band.
What they found: Signs of ADHD tracked closely with hating delay and with restless, upset waiting. The pattern looked the same in both countries.
What it means for you: Waiting packs come with extra support and shorter steps. The kids who find waiting hardest get the most help, not the least.
103Moderate
Playing beside others is real play. It is a stage, not a failure.
Parten (1932), Journal of Abnormal and Social Psychology 27, 243 to 269.
Moderate (as a definition anchor): classic taxonomy, not an engagement-duration finding
Who was studied: Preschoolers, ages 2 to 5, watched at play in 1932. Below our band.
What they found: Many young kids play on their own right next to other kids. Sand play and building were the most common forms. This side by side play fades as kids grow.
What it means for you: A pack can set your kid up beside you while you work. Side by side counts. Your kid does not have to join in every minute.
104Moderate
Most 9 and 10 year olds want to pitch in at home.
Coppens, Alcalá, Mejía-Arauz & Rogoff (2014), Human Development 57, 116 to 130.
Moderate: small, qualitative, but directly in-range and directly on kitchen-adjacent work
Who was studied: 16 kids, ages 9 to 10, in two Mexican communities.
What they found: Nearly every kid wanted to help with housework. They saw it as a shared family job. Kids from Indigenous heritage homes more often started big jobs on their own.
What it means for you: Kitchen packs frame your kid as a real helper. Helping is the point. It is not a trick to keep them busy.
105Moderate
Kids learn by watching real work and joining in.
Coppens et al. (2014) companion paper, Human Development 57, 150 to 161 (LOPI framework; Rogoff 2014).
Moderate: framework, not an effect size
Who was studied: This is a framework paper. It sums up research on how kids learn in daily life. There is no single group of kids.
What they found: In many homes, kids learn by being near adult work. They watch first. Then they take a real step themselves. Then they drift back to their own play.
What it means for you: Kitchen packs follow that rhythm. Watch a step. Do a step. Play a bit. No parent has to run a lesson.
106Thin
Kids sometimes play better when the adult steps back.
Greenwood & MacDonald (2004), Psi Chi Journal of Undergraduate Research 9(2), 51 to 56.
Thin: undergraduate outlet, small, below-range, but the direction matters for design
Who was studied: 32 preschoolers playing in pairs. Below our band. One small study in a student journal.
What they found: Pairs showed fewer good play behaviors with a familiar adult present than with the adult gone. Pairs of boys cooperated most. Pairs of girls played side by side most.
What it means for you: Kitchen packs put you nearby, not in charge of the play. Your presence is the background. It is not the show.
107Moderate
A much older playmate smooths the game.
Liu & LaFreniere (2014), Human Ethology Bulletin 29(1), 4 to 17.
Moderate: experimental contrast, but small and below-range
Who was studied: 20 pairs of preschoolers, ages 4 to 6. Just below our band. Some groups matched by age. Some mixed ages, with a partner about 5 years older.
What they found: Mixed age groups played longer and shared more fairly. Their turns ran smoother and their work went better. Same age groups spent more time getting in each other's way or drifting off.
What it means for you: Sibling packs give the older kid the guide role and the younger kid the action role. Different jobs beat the same job twice.
108Moderate
Older siblings fight more, not less. They also grow warmer.
Vandell, Minnett & Santrock (1987), Journal of Applied Developmental Psychology 8, 247 to 257.
Moderate: in-range, observational, with a hypothesis-defying result
Who was studied: 73 pairs of brothers and sisters, ages 4 to 11. Researchers filmed 30 minutes of play.
What they found: As siblings grew, power evened out and teaching dropped. Warmth and good tone rose. But fighting rose too, most sharply from age 8 to about 10 or 11. That surprised the researchers.
What it means for you: Sibling packs for older kids expect sparks. Turn rules and split roles channel them. We never promise that age brings peace on its own.
109Moderate
Kids play one way with siblings and another with friends.
Leach, Howe & DeHart (2019), Infant and Child Development 28(6).
Moderate: longitudinal, within-child sibling-vs-friend contrast
Who was studied: 65 kids at about age 4 and a half, then 46 of them again at ages 7 to 8. Each kid was watched with a sibling and with a friend.
What they found: With friends, kids built shared meaning in warmer ways. With siblings, kids proposed more new ideas. By ages 7 to 8, kids in both pairings built on each other's ideas more.
What it means for you: Sibling packs are built for new ideas flying back and forth. We do not judge sibling play by how smooth friend play looks.
110Moderate
Toddlers can help and comfort. They just rarely choose to.
Dunn & Munn (1986), International Journal of Behavioral Development 9(3), 265 to 284.
Moderate (as background): foundational, but far below range
Who was studied: 43 families with two kids. Home visits happened at 18 months and 24 months. Far below our band. This one is background only.
What they found: Even at that age, kids could share, help, and comfort. They seldom felt like it. Kind moves did flow both ways over six months. A helpful older sibling tended to get a helpful younger one.
What it means for you: Turn taking as the helper runs through sibling packs from the start. We never expect the little one to offer help out of nowhere.
111Thin
Copying is how kids join a game. Everyone likes being copied.
Howe, Paine, Leach, Magazin, Gilmore and DeHart (2023), Social Development 32(3), 1060 to 1074 (companion to SCN-18).
Thin: secondary sourcing, details incomplete
Who was studied: Kids followed over time, watched with siblings and with friends. The report we read did not confirm exact numbers or ages.
What they found: Kids copied friends more than siblings at first. Every partner responded well to being copied. Copying words was the most common form, mostly while sorting out a game or pretending.
What it means for you: Copycat games are an easy first step into playing together. They ask for almost no courage from a shy kid.
112Moderate
Green outdoor play eased ADHD symptoms more than any other setting.
Kuo & Faber Taylor (2004), American Journal of Public Health 94(9), 1580 to 1586.
Moderate: large, consistent, but parent-report and nonprobability
Who was studied: 452 parents of kids ages 5 to 18 with ADHD. They rated 49 activities. This is parent report, not a trial.
What they found: Green outdoor activities eased symptoms more than built outdoor or indoor ones. The pattern held across age, sex, income, and region. Green settings helped even in big groups.
What it means for you: Outdoor packs are the go to version when focus is the goal. We call them support, never treatment.
113Moderate
A park walk sharpened focus more than a city walk.
Faber Taylor & Kuo (2009), Journal of Attention Disorders 12(5), 402 to 409.
Moderate: experimental, in-range, but N=17 and ADHD sample
Who was studied: 17 kids, ages 7 to 12, with ADHD. Each child took three guided 20 minute walks. One in a park, one downtown, one in a neighborhood.
What they found: After the park walk, kids scored better on a focus and memory test. The park beat both other walks. The group was small.
What it means for you: A 20 minute nature walk works as a reset before a pack that needs focus. We do not promise the same size of boost for every kid.
114Moderate
A nature walk sped up attention. It did not fix everything.
Schutte, Torquati & Beattie (2017), Environment and Behavior 49(1), 3 to 30.
Moderate: experimental, in-range school-age group, with explicit nulls
Who was studied: 34 kids ages 7 to 8 and 33 preschoolers ages 4 to 5. All did tiring puzzles, then walked in nature or in town.
What they found: Kids answered an attention task faster after the nature walk. School age kids gained more than preschoolers. The walks did not change impulse control or word memory at all.
What it means for you: Nature resets in packs aim at attention only. We never claim a walk boosts every kind of thinking.
115Moderate
Risky outdoor play moved kids more and hurt almost none.
Brussoni et al. (2015), International Journal of Environmental Research and Public Health 12(6), 6423 to 6454.
Moderate: systematic review, but evidence quality ranged very low to moderate
Who was studied: A review of 21 papers on kids ages 3 to 13. One large follow up tracked more than 25,000 kids for a year.
What they found: Places that allow risky play got kids moving more and sitting less. Rough play was not tied to more aggression. No serious injuries showed up in the big follow up. Minor bumps are normal. One study found risky play cut activity when an adult was watching.
What it means for you: Outdoor packs include climbs, speed, and tools your kid judges for himself. You stay close. You do not hover over every move.
116Moderate
The bigger review is more careful about risky play.
Ramsden et al. (2026), PLoS One 21(10), e0347444 (PROSPERO CRD42023488023).
Mixed: the largest synthesis, and it directly qualifies SCN-24
Who was studied: 74 studies of kids ages 3 to 12, gathered in one large review.
What they found: Risky play and places that allow it linked to gains in many areas. Rough and tumble play was the odd one out. Its results were mixed, and it linked to more aggression, not less. Overall proof quality was low to middling.
What it means for you: We keep general risky play and drop the rough play promises. Where this review clashes with the older one, we follow this one.
117Moderate
Kids move more than twice as much outdoors.
Tandon, Saelens, Zhou & Christakis (2018), International Journal of Environmental Research and Public Health 15(11), 2463.
Moderate: objective measurement, but preschool and observational
Who was studied: 46 preschoolers, mean age 4 and a half. Below our band. Sensors tracked their movement for five days at childcare.
What they found: Activity counts more than doubled outdoors versus indoors. Kids sat still 51 percent of outdoor time and 75 percent of indoor time. Strong movement was 31 percent outdoors and 12 percent indoors.
What it means for you: The outdoor version of a high energy pack is the default, not the bonus. The indoor twin will not deliver the same movement.
118Moderate
A kid who likes playing alone is not the same as a shy kid.
Coplan & Weeks (2010), Merrill-Palmer Quarterly 56(2), Article 2.
Moderate: in-band and multisource, but correlational, and the outcomes are adjustment rather than play engagement
Who was studied: 186 kids, ages 6 to 8. Mothers and teachers rated them, and the kids were interviewed.
What they found: Kids who prefer playing alone looked just like other kids on worry, friend trouble, and loneliness. Shy kids fared worse on all three. Boys who prefer alone time showed some extra friend trouble.
What it means for you: Solo packs are a real choice, offered with pride. We ask whether your kid prefers alone time or wants in and holds back. Those are different kids.
119Moderate
Liking time alone carries no direct path to friend trouble.
Coplan, Rose-Krasnor, Weeks, Kingsbury, Kingsbury & Bullock (2013), Developmental Psychology 49(5), 861 to 875.
Moderate: large N and mechanism-level modeling, but half the sample sits above the band and outcomes are adjustment, not engagement
Who was studied: 367 kids, ages 9 to 12. Kids reported on themselves. Teachers watched the schoolyard. Parents reported friend trouble.
What they found: Liking solitude predicted playing alone. It did not lead straight to friend trouble. Shyness did take that direct path. Kids who were both shy and avoidant fared worst of all.
What it means for you: A solo pick at age 9 or 10 stays a fine pick. Our care goes to the shy kid who also pulls away, not to the kid who simply likes quiet.
120Moderate
One long study pushes back on the solo story.
Kopala-Sibley & Klein (2017), Journal of Research in Personality.
Moderate: longitudinal and baseline-adjusted with its endpoint inside the band, but parent-report measures throughout and symptom outcomes, not play outcomes. Entered at full strength as the standing disagreement with SCN-27 and SCN-28
Who was studied: 493 kids, checked at ages 3, 6, and 9. Parents rated shyness, interest in others, and symptoms.
What they found: Kids who showed little interest in company at age 6 had more anxiety by age 9. Boys also showed more low mood. Shy kids showed the same pattern earlier, from 3 to 6. This study clashes with the two above it.
What it means for you: We treat solo as a current pick, not a fixed trait. Packs keep a warm, low pressure invitation open. We never market solo play as risk free for every kid.
121Moderate
A quiet kid joins in fully once the talk starts.
Asendorpf & Meier (1993), Journal of Personality and Social Psychology 64(6), 1072 to 1083.
Moderate: in-band, naturalistic, week-long measurement; small selected sample and a speech outcome rather than play
Who was studied: 41 second graders, about ages 7 to 8. Their talk and heart rate were tracked for a full week.
What they found: Kids who prefer alone time started fewer talks. Once in one, they joined in just as much as anyone. Shy kids kept up fine in familiar places. They fell behind only in newish ones.
What it means for you: Partner and group packs stay on the menu for the solo kid. For the shy kid, a familiar partner in a familiar place is the on ramp.
122Moderate
Friends solve problems better than kids who just know each other.
Azmitia & Montgomery (1993), Social Development 2(3), 202 to 221.
Moderate: in-band at the top edge, experimental pairing; a cognitive task rather than play
Who was studied: 72 fifth graders, about ages 10 to 11. Each worked with a friend or with a classmate they barely knew.
What they found: Friend pairs got more answers right during the task and on a later test. Friends checked each other's work more. They explained their thinking and built on it.
What it means for you: Bring a friend is its own pack setup. It is not the same as a sibling setup or a parent setup. The boost belongs to real friendship.
123Moderate
Friend play runs longer in one stretch. Sibling play runs in bursts.
Leach, Howe & DeHart (2019), Early Education and Development 30(6), 709 to 723.
Moderate: longitudinal and observational with an in-band second wave, but small N, and the duration measure is connected-sequence length within a session, not total play time
Who was studied: 44 families. Each child was watched playing with a sibling and with a friend at age 4 and again at age 7.
What they found: At age 7, friend play ran in longer unbroken runs. Sibling play came in shorter bursts. Both matched on growing cooperation and on warm tone.
What it means for you: Sibling packs are built as short bursts with easy ways back in. We never call sibling play worse. It just has a different rhythm.
124Moderate
Feeling bad about an unfair advantage develops across middle childhood.
Gerdemann, McAuliffe, Blake, Haun & Hepach (2022), Royal Society Open Science
Moderate: a registered report with an objective posture measure, in band; one study
Who was studied: Children ages 4 to 10 in dyadic distribution tasks, with a nonsocial control condition.
What they found: Negative social emotion was measured as lowered body posture. Older children showed more negative emotion after unintentionally disadvantaging a peer than after a fair outcome; younger children showed the reverse pattern. The nonsocial control showed no such pattern. Discomfort at an unfair advantage is a middle childhood development, not a starting state.
What it means for you: Fairness mechanics, handicaps, and honest scorekeeping are pitched to land at 8 to 10. At 5 to 6, rule bending to avoid losing is a stage, not a character flaw.
125Moderate
Children's relation to game rules changes in stages.
Piaget (1932), The Moral Judgment of the Child
Moderate: the stage direction is unchallenged and converges with the fairness timing; the ages come from 1932 observation in one culture
Who was studied: Swiss children observed and interviewed about marbles and other games, preschool through about age 12.
What they found: Four stages: a motor and individual stage; an egocentric stage, about ages 2 to 5, in which children play together but each on his own and everyone can win at once; a stage of incipient cooperation, from about 7 to 8, in which winning becomes the point and rules are followed but still understood inconsistently; and a codification stage, about 11 to 12, in which rules are known in detail, held in common, and changeable by agreement.
What it means for you: Everyone-can-finish formats and no lone loser at 5 to 6. Printed, short, complete rules at 7 to 8, because this band litigates any gap left to common sense. Rule changing by group agreement is printed as a permission at 9 to 10.
126Background
Parents are running on fumes. The product has to hold the line, not the parent.
American Psychological Association findings, as recorded in brief (§12)
Recorded in §12 as the design consequence's basis
Who was studied: US parents, set against other adults.
What they found: 48 percent of parents call their stress completely overwhelming. The figure for other adults is 26 percent. 41 percent of parents say they are sometimes so stressed they cannot function.
What it means for you: Sessions end on their own. The ending never rests on a parent's willpower. And our copy relieves parents. It never indicts them.
127Moderate
Only about 1 in 10 kids collects things. It peaks near age 10.
Lehman & Witty (1927), Psychological Review 34(1), 48 to 56.
Moderate: historical survey, but the "no spike" and "peak at 10" pattern is the only age-graded collecting data in hand
Who was studied: A large group of children, surveyed long ago in 1927.
What they found: Collecting did not suddenly switch on at any age. Only about 10 percent of children were actively collecting. The effort they put into it peaked at age 10. Older children lost interest.
What it means for you: Collecting can be one fun option near ages 9 and 10. It is not the engine of the product. Most kids are not collectors.
128Moderate
Toddlers who hung back still hung back at 7, when a new group game shut them out.
Walker, Henderson, Degnan, Penela & Fox (2014), Social Development 23(3), 487 to 501
Moderate: in-band outcome age with direct observation; the trait was measured in toddlerhood, so it speaks to stability of the disposition, not to a parent rating taken at age 7
Who was studied: Children followed over years. Shyness was measured at ages 2 to 3 by mothers and by lab watchers. Social behavior was watched at age 7 in a live game with strangers that turned excluding.
What they found: The more a toddler hung back from new things, the more he withdrew at 7. He also came up with fewer bold solutions to the social problem. This was one new session only. The study never timed how long warming up takes.
What it means for you: New social missions open slow on purpose. Watching first is allowed. Joining late is allowed. A slow starter may still be finding his feet deep into a first session with new people. We never quote a warm-up time in minutes. No study here measured one.
129Strong
Shy behavior follows steady paths. Many slow starters do not simply warm up and catch up.
Poole, Degnan, Harrewijn, Almas, Fox & Henderson (2022), Child Development 93(5), 1334 to 1346
Strong for the shape of the phenomenon across the exact band: repeated direct observation at 5, 7, and 10; the task is a speech performance, so transfer to play formats is an inference
Who was studied: 227 children. Each gave a short speech at ages 5, 7, 10, and 13 while researchers watched. Shyness was measured at ages 2 to 3.
What they found: Three paths showed up. One group stayed high in shy behavior. One group rose over time. One group stayed low. Strong early shyness pointed to the high steady path. Only about half of the teens with social anxiety had been shy toddlers, so early shyness is one road, not a gate.
What it means for you: We never assume a slow starter joins in by the third try. The kinder design repeats the same gentle shape with new fill, instead of throwing new formats at him. And one hard first session measures nothing about a child. We judge across several outings.
130Thin
What set struggling kids apart was not bigger blowups. It was slower calming down.
Scheper, Majdandžić, van de Ven, Jansen, Doreleijers, Schuengel & de Vries (2017), Child Psychiatry and Human Development 48(6), 841 to 850
Thin for this product: the recovery construct and its parent observability are directly supported, but the sample is young and clinical; take the direction and the separability, not the sizes
Who was studied: 115 children referred for emotional and behavior problems, matched with 115 children from the general public. Ages 3 to 7, mostly below our band. Parents filled in a temperament form.
What they found: The two groups reacted with the same overall strength of bad feeling. One part differed. The referred children calmed down more slowly after upset. That slower calming also tracked with more anxiety and acting out problems.
What it means for you: We ask parents two separate questions. How big is the blowup. And how long until he is himself again. They are different facts. Packs build in a calm way back in after a hard moment. We take the direction from this study, not its numbers, since the children were young and in clinics. Slow calming is a pace to design around, never a defect to fix.
131Strong
What your child already loves is the best guide to what will hold them.
Grounded in §7 choice evidence and Ryan & Deci (2000), as graded in §17
Strong support (§17)
Who was studied: Children, through what their parents report.
What they found: Choice is what grabs attention. A child's own interests are what keep them going back.
What it means for you: The survey asks what your child chases. The pack's mix follows that answer. We never ship a balanced pack that ignores it.
132Moderate
Kids start in different ways. Some copy. Some listen. Some invent first.
Brief §6 and §17 (pathways literature as summarized)
Moderate support (§17)
Who was studied: Children, through parent report and the child's own picking.
What they found: Starting side by side or alone changes how play goes. Watching others and joining in carry their own pull. A starting way is a door a child picks. It is not a trait stamped on them.
What it means for you: Every activity has more than one door in. Watch and copy. Listen along. Start solo. Start together. The survey asks how your child likes to start.
133Thin
Parents can see if a child is competitive, careful, social, or solo. Science has not tested matching to it.
No trial literature cited in brief (§17)
Thinner evidence; honest grade (§17): parent-reported preference routing, claimed at that strength and no higher
Who was studied: Children, through parent report only.
What they found: These leanings are real and a parent can see them. Matching the format to them follows from the choice research. But no strong trial has tested content picked by personality.
What it means for you: We do match format to what you tell us. Head to head or side by side. We say plainly that this is matching a preference. We never call it proven.
134Strong
New starters and old hands need different material. That difference is real and measured.
Expertise literature as summarized in brief (§6); graded again in §17
Strong support (§§6, 17)
Who was studied: Learners in general. The brief applies it to children.
What they found: Help that lifts a beginner can hold back a child who already knows the material. That crossover shows up in test after test. It is the same crossover that learning styles never produced.
What it means for you: Packs step up as your child gains ground. One difficulty for everyone is the wrong design. And our adapting rests on experience, never on style.
135Moderate
Wanting to play alone is a real preference. It is not the same as shyness.
Grounded in Coplan & Weeks (2010), Coplan et al. (2013), and Asendorpf & Meier (1993), entered at SCN-27, SCN-28, and SCN-30; qualified by Kopala-Sibley & Klein (2017) at SCN-29.
Moderate support, claimed at preference strength. This upgrades the social/solo clause of FIT-03 from "thinner evidence" for this one dimension only; no study has tested whether matching format to preference changes holding time, so the grade stops at Moderate
Who was studied: Children ages 6 to 12 across three studies. Two sit inside our age band. One reaches its top edge.
What they found: Children who prefer solo play join in fully once they start. At ages 6 to 8 they looked the same as other kids on how well they were doing. Shyness, not the solo preference, was the path to trouble with peers. One study adds a caution. Social disinterest at age 6 came with more symptoms by age 9.
What it means for you: The survey asks who your child plays with best. Alone. Beside others. With a partner. In a group. The pack follows that answer as a preference for now. It is never printed on your child as who they are. No study has tested whether matching format lengthens play, so we claim no more than a good match.
136Thin
Kids can report their own boredom. Parents read it differently than teachers do.
Carrington (2019), "Development of a school boredom proneness scale for children", Educational Specialist thesis, James Madison University.
Thin: an unpublished master's-level thesis and a single sample, but the only child self-report boredom proneness scale development found in this harvest, and its informant pattern is the finding
Who was studied: Elementary school children. The children, their parents, and their teachers all gave ratings. The thesis record does not state the sample size.
What they found: A 15 question boredom scale for children held together as one score. Its five part scores did not. High scores matched the child's own reports of boredom. They matched teacher ratings too. They did not match parent ratings at all. Kids with high scores also finished less school work, per their teachers.
What it means for you: Our boredom question asks what you can see. How often boredom strikes your child, next to other kids. We never ask you to rate an inner trait. And your read counts as one voice among several.
137Moderate to strong
Some children feel their surroundings more strongly. About one in five to one in three do.
Pluess, Assary, Lionetti, Lester, Krapohl, Aron & Aron (2018), Developmental Psychology 54(1), 51 to 70.
Moderate to Strong as distribution and measurement evidence: large multi-sample psychometrics, discounted because the paper shows the trait exists and can be measured, not that it predicts play choices
Who was studied: 3,581 children and teens, ages 8 to 19, across five studies. The child samples run ages 8 to 12. The teen samples stretch the range.
What they found: A 12 question scale measured this sensitivity well. It stood apart from other temperament traits. Every sample split into three groups. Low ran about 25 to 35 percent. The middle ran about 41 to 47 percent. High ran about 20 to 35 percent. The high group feels bad settings and good settings more strongly than the rest. The cut lines between groups are early work, not settled.
What it means for you: Your child's profile can note sensitivity from what you see. Noise. Crowds. Sudden change. Scratchy or bright settings. The same missions then come in calmer versions. Sensitive never means fragile here, and it never means easier missions. It means less overload. The word itself never gets printed on your child.
138Strong
Senses that bother a child are common. About one in six kids has several.
Ben-Sasson, Carter & Briggs-Gowan (2009), Journal of Abnormal Child Psychology 37(5), 705 to 716.
Strong for prevalence (representative, in band, longitudinal cohort); the social and emotional links are correlational
Who was studied: 925 children, ages 7 to 11, in a broad sample followed since babyhood.
What they found: 16 percent of parents reported at least four touch or sound feelings that bother their child. Kids with high bother levels also had more social and emotional difficulty. Those links show a pattern. They do not prove cause.
What it means for you: Sound and touch load is part of how we shape a pack. Group and party missions come in a low load version. The survey asks about noises and textures that bother your child, in plain behavior words. We note a preference. We never screen for a condition.
139Moderate to strong
A second country lands in the same place. About one in five kids flags on a senses checklist.
Nielsen, Brandt & la Cour (2021), Occupational Therapy International 2021, article 8893345.
Moderate to Strong for prevalence convergence with FIT-08 (different country, instrument and sampling frame); screening cut offs on a parent questionnaire overstate clinical difficulty, as the study itself notes
Who was studied: 1,723 Danish school children, ages 5 to 11. Parents filled in the checklist.
What they found: 21.3 percent scored in the range that suggests senses difficulties. The most common pattern was the opposite of bother. Some kids under respond and go hunting for strong input. That flag hit 32.7 percent. Trouble filtering sound came next at 31.1 percent. Boys flagged more often than girls. Kids in out of school sports flagged less, and nobody knows which way that link runs.
What it means for you: We plan pack load for a sizable minority, not a rare case. Missions that feed the hunt for strong input are a first class family here. And 21 percent is a checklist flag. It is not a diagnosis rate, and we never quote it as one.
140Moderate
Thrill seeking can be measured in kids from about age 7.
Russo, Lahey, Christ, Frick, McBurnett, Walker, Loeber, Stouthamer-Loeber & Green (1991), Personality and Individual Differences 12(5), 399 to 405.
Moderate as the measurement origin for the trait in band; small non-referred sample, and the instrument lineage after this paper is unstable (FIT-11)
Who was studied: 126 children, ages 7 to 12, plus 176 boys sent to a clinic, ages 7 to 22. The clinic group had behavior problems and runs above our age band.
What they found: A children's version of the thrill seeking scale worked in both groups. Scores tracked behavior problems. Boys in the clinic group chased stimulation because they were bored. In that group the boys' scores also matched their mothers' scores.
What it means for you: A taste for thrill and intensity is a real thing we can ask about from about age 7 up. Nothing in our copy ties thrill seeking to bad behavior. That link came from a clinic sample. It says nothing about an ordinary kid who loves a fast hill.
141Moderate
Only part of the thrill scale holds up in kids today. Thrill and holding back do. Boredom scores do not.
Sandseter, Sando, Kleppe, Lorås & Storli (2024), Frontiers in Psychology 15, 1341609.
Moderate: one country's revalidation, but directly in band, recent, and convergent with the earlier reliability complaints it reviews
Who was studied: 393 Norwegian children, ages 7 to 10.
What they found: The old scale's shape fell apart under testing. Two parts survived. Thrill and intensity seeking held. So did holding back. The boredom and novelty parts scored too unsteadily to use. Boys scored higher on thrill and intensity. Girls scored higher on holding back.
What it means for you: The survey reads thrill taste through real activity picks. It never turns your child into a thrill score. We do not route on boredom proneness or novelty seeking scores. The tools for those are not steady enough.
142Thin
Just above our age band, the two ends of the senses range pull opposite ways.
Choi & Jung (2021), Children 8(11), 1005.
Thin to Moderate for this product: the only direct participation evidence covering both poles found in this harvest, discounted for adjacent ages, one country, and a correlational design
Who was studied: 140 Korean elementary students, ages 11 to 12. That sits above our band. The checklist used is made for ages 11 and up.
What they found: Kids who seek strong input joined more kinds of leisure and enjoyed it more. Kids who are sensitive, and kids who barely notice input, joined less. Formal lessons and skill classes split the groups the most.
What it means for you: Expect the seeker and the sensitive child to react in opposite ways to the same pack. The sensitive child gets a lower load route into the same mission. Never a smaller, lesser pack. The direction of this finding is what we use. The sizes come from older kids and do not transfer down as numbers.
143Strong
Grit is mostly an old trait with a new name.
Credé, Tynan & Harms (2017), Journal of Personality and Social Psychology 113(3), 492 to 511.
Strong (as a caution): a top journal meta-analysis of the whole literature; it caps what any grit framed routing may claim, in any age band
Who was studied: A review of 88 samples with 66,807 people. Most were adults and older students. Direct proof in children is scarce in the pool.
What they found: Grit's two halves do not form one trait. Only the keep trying half predicts results. The other half, staying with one interest, does not. Grit scores matched plain carefulness very closely, about 0.84. Once carefulness was counted, grit added little. The authors conclude that trying to raise grit may do only a little.
What it means for you: We route on what we can watch a child do after a failure. We never ask for a grit score. No pack label and no pack match ever calls a child gritty or not gritty.
144Strong
The eager child and the quick to flare child are often the same child.
Deater-Deckard, Beekman, Wang, Kim, Petrill, Thompson & DeThorne (2010), Journal of Personality 78(3), 991 to 1010
Strong for measurement and distribution at the bottom and middle of the band: two large samples and a standard instrument; correlational, and a single reporter (mothers)
Who was studied: Mothers rated children ages 4 to 9. One sample held 992 children from across the country. The other held 195 pairs of same sex twins.
What they found: Frustration and anger sat near the middle to high end of the scale, about 4.7 out of 7. It was spread wide, not a rare extreme. It tracked mother rated aggression at .52. Eagerness itself tracked frustration at .44. The keen rush toward a reward and the flare when it is blocked arrive together. Boys and girls looked alike on this.
What it means for you: The survey asks about frustration you can see. Losing temper when a game goes wrong. When told to stop. When a turn is denied. And packs your eager child loves come with a plan for the flare ups. Keen never gets read as calm here. It never gets read as bad character either.
145Moderate to strong
Frustration at 6 to 9 still showed in behavior nearly four years later.
Zhou, Wang, Deng, Eisenberg, Wolchik & Tein (2008), Child Development 79(3), 493 to 513
Moderate to strong for the routing claim: longitudinal, in-band, two informants, and a cross-cultural replication of United States findings; the outcomes are problem behavior, not play engagement
Who was studied: 425 Beijing schoolchildren, ages 6 to 9 at the start. Both parents and teachers rated them. The children were followed for 3.8 years.
What they found: Anger and frustration early on predicted later behavior problems, even with parenting counted. Strong self control predicted fewer problems. Harsh parenting did part of its damage through the child's belief that he can handle hard moments and the feelings they bring.
What it means for you: A parent answer about frustration is solid enough to route a pack on. Pack cards for frustration prone kids name what to do when it goes wrong. That builds the child's belief that he can cope. We never promise a pack cuts behavior problems.
146Moderate
Two kinds of perfectionism live in kids. One hurts. One protects.
Lozano, Valor-Segura, García-Cueto, Pedrosa, Llanos & Lozano (2019), Frontiers in Psychology 10, 1855
Moderate: a very large sample at the top of the band and a validated child instrument; cross-sectional, and the reporter is the child, so parent survey items must target the observable residue (redoing work, erasing through the paper, refusing to show a finished piece, distress out of proportion to the mistake) rather than the inner state
Who was studied: 2,636 Spanish schoolchildren, ages 8 to 12. They reported on themselves. That runs to the top of our band and above it.
What they found: Pressure felt from outside predicted irritability. It predicted feelings of worthlessness, thinking problems, and body symptoms too. The harm ran through harsh judgment of the self. High standards a child sets for himself did the opposite. They protected him.
What it means for you: At the top of the band, mistake moments stay private. Drafts are expected and called drafts out loud. No pack ever shows off a child's failed try. The survey asks about what you can see. Redoing work. Erasing through the paper. Refusing to show a finished piece. We never print the word perfectionist on a child. High standards are not the problem here. The evidence points the other way.
147Moderate
Slow to warm up is worth designing around. It is never a thing to screen for.
Hirshfeld-Becker, Biederman, Henin, Faraone, Davis, Harrington & Rosenbaum (2007), Journal of Developmental and Behavioral Pediatrics 28(3), 225 to 233
Moderate as a fence, thin as a fit claim: prospective and specific, but the sample is risk-enriched and the measurement predates the band; it disciplines how the variable may be used, it does not size an effect for typical buyers
Who was studied: 284 children watched for shyness between 21 months and age 6. Many had parents with panic or depression, so risk ran high in the group. 215 were checked again at about age 9.6. The trait was measured before our age band.
What they found: Shy young children showed social anxiety across their lives at 28 percent, against 14 percent. New cases among those clear at the start ran 22.2 percent against 8.0 percent. No other anxiety type was predicted. The forecast was narrow, not general.
What it means for you: Packs for slow starters begin with the familiar. Joining in is gradual. We claim comfort and fit only. We never claim a pack prevents anxiety. And no question in our survey screens, flags, or labels a child. This entry is a fence. It tells us how gently to design, and where we must never go.
148Strong
Loose parts are fun. Proof they build skills does not exist.
Gibson, Cornell & Gill (2017), School Mental Health 9(4), 295 to 309.
Strong (as a null): systematic review with explicit quality judgement
Who was studied: A review of every solid study on loose parts play. Only 5 studies passed the bar. All used primary school children.
What they found: No study showed gains in friendship, social skill, or quality of life. No study even measured thinking or school outcomes. Enjoyment and self esteem showed small positive signs. The famous loose parts theory from 1972 is a theory. It is not evidence.
What it means for you: Open ended stuff earns its place because kids enjoy it and lead it themselves. We never say loose parts improve social skills or learning. The review says that proof is not there.
149Moderate
A yard full of loose stuff did not lengthen play. Not one bit that counted.
Bundy et al., Sydney Playground Project (cluster RCT; protocol Bundy et al. 2011, BMC Public Health 11:680), as tabulated in Gibson et al. (2017).
Moderate: cluster RCT, in-range, null on the exact outcome this product cares about (engagement time)
Who was studied: 226 children, ages 5 to 7, in 12 Australian primary schools. Their playgrounds got tyres, crates, and hay bales for 13 weeks.
What they found: Time spent engaged in play did not change in any way that counted. The number of playmates did not change either. Teachers also got talks on letting kids take risks.
What it means for you: Loose materials are one ingredient. They are not a promise of longer play. This study tested the exact thing parents hope for, and it came up empty.
150Strong
People understand reading better on paper than on screens.
Delgado, Vargas, Ackerman & Salmerón (2018), Educational Research Review 25, 23 to 38.
Strong for the general effect; Moderate for ages 5 to 10 specifically (few young-child studies in the pool)
Who was studied: 54 studies with 171,055 people. Most readers were teens and adults. The proof in young children is indirect.
What they found: Paper held a small, steady edge in understanding, in both kinds of test design. The edge grew under time pressure. It showed for fact based texts and mixed texts. It did not show for stories alone. Across the years studied, the paper edge grew. It did not shrink.
What it means for you: Instructions and anything a reader must truly take in come in print. We say understanding runs better in print on average, and only for fact based texts. This effect is strong in general and middling for ages 5 to 10, where few young child studies sit in the pool.
151Moderate
In strict experiments, screens lost to paper on fact texts. Stories tied.
Clinton (2019), Journal of Research in Reading 42(2), 288 to 325.
Moderate: randomized evidence only is a strength; population and text-type limits are real
Who was studied: 33 experiments with 2,799 readers. Most were teens and adults.
What they found: Screens came out behind paper overall. The whole gap sat in fact based texts. Story texts showed no real difference. Reading time did not differ either. Readers also judged their own understanding more accurately on paper.
What it means for you: Anything your child or you must follow exactly goes on paper. Rules. Steps. Orders of play. We never stretch paper beats screens into a blanket claim about stories. Two separate reviews agree it does not cover them.
152Moderate
For young kids, a book moved to a screen got worse. A screen book built for its story could beat print.
Furenes, Kucirkova & Bus (2021), Review of Educational Research.
Moderate: directly on-age and nuanced, but primary studies are small and effects are design-dependent
Who was studied: 39 studies with 1,812 children, ages 1 to 8. This is the one review here inside our age range.
What they found: A print book simply put on a screen lowered story understanding. An adult reading a print book with the child did better than the built in extras in books children read alone on a screen. But screen books whose extras fit the story beat print. Built in word lists helped word learning. They did not help understanding, and sometimes hurt it.
What it means for you: A print book needs no battery and no stand in for the adult to give its full value. Adult help lifts print most of all. That suits a pack a parent runs. We never claim screens cannot teach reading. A well built screen book beat print in this research. Our edge is plainness and the parent, not a law about screens.
153Thin
Young readers read faster in bigger print. Shrinking it early costs them.
Wilkins, Cleave, Grayson & Wilson (2009), Journal of Research in Reading 32(4), 402 to 412.
Thin-to-Moderate, small laboratory studies, but direct measurements in the target age range on the exact design variable (print size/face)
Who was studied: Four studies with children mainly ages 7 to 9. Background work ran from ages 5 to 11.
What they found: Sentences in a taller letter size were read and checked 9 percent faster than a smaller one. Keeping a reading test at its first, larger print size raised the measured reading age by four months. A plain typeface beat the special child marketed one for speed.
What it means for you: Child facing print in our packs runs large, with uncrowded pages. That matters most at ages 5 to 7. The research backs bigger than usual and do not shrink early. It names no magic point size, and neither do we. We also pay no premium for novelty typefaces sold for kids. The one tested was read more slowly.
154Moderate
Reading level climbs steeply across the band and spreads widely inside every grade.
Lexile reader measure grade norms (MetaMetrics), as published at schooltest.org; Nemours KidsHealth, Reading Milestones
Strong for the shape of the progression; moderate for any exact Lexile number, since norm tables differ by publisher and by what they measure
Who was studied: US school children, kindergarten through grade 5, in the national norm samples behind the Lexile framework.
What they found: One widely published reader norm table runs from beginning reader levels in kindergarten to 770L to 1080L in grade 5. A second published table, the Common Core stretch bands, sets text difficulty targets rather than reader levels, and the two answer different questions. The Nemours milestones agree on the shape: kindergarten reads simple words; grades 1 to 2 sound out unfamiliar words and use pictures and context; grades 2 to 3 read longer books independently; and from grade 4, children read to extract specific information.
What it means for you: Text load budgets per band: headline words plus picture steps at 5 to 6, with full instructions on the grown-up side; short numbered paragraphs at 7 to 8; 80 to 120 words a card at 9 to 10. Any 5 to 6 pack that requires the child to read instructions in order to start is a design failure.
155Moderate
Canada caps fun screen time at 2 hours a day.
Tremblay et al. (2016), Applied Physiology, Nutrition, and Metabolism 41(6 Suppl. 3), S311-S327 (Canadian 24-Hour Movement Guidelines for Children and Youth).
Moderate: a rigorous, GRADE-based national guideline, but the screen figure is a consensus threshold built largely on observational evidence, not a tested cut-point
Who was studied: Canada's official movement guide for ages 5 to 17.
What they found: The guide pairs the active hour with a cap of 2 hours a day of fun screen time. It also sets sleep at 9 to 11 hours for kids up to 13.
What it means for you: In Canada that 2 hour line is official. We never pass it off as a world rule. It is one country's line, built on softer proof.
156Moderate
Lots of screen time links to harm. The safe line is unclear.
Stiglic & Viner (2019), BMJ Open 9, e023191.
Moderate: a careful umbrella review whose own conclusions are explicitly hedged
Who was studied: A review of 13 other reviews. Kids and teens up to 18.
What they found: High screen time came with more weight gain and more low mood. Proof for a safe cutoff was weak. Small amounts of screen time were not shown to harm kids.
What it means for you: We can say heavy screen time is a real worry. We cannot name a magic safe number. We do not claim small screen use harms a kid.
157Moderate
Swapping screens for play may not add up the way you hope.
Beck, Engel & Reimers (2022), Children 9(3), 351.
Moderate: systematic review of objectively measured studies; its honest verdict is "we don't know"
Who was studied: A review of 77 studies with about 41,000 kids and teens. Activity was measured by devices, not by asking.
What they found: Kids who moved more in one part of the day sometimes moved less later. The studies could not settle whether the day evens out.
What it means for you: We promise 30 minutes of active, screen free play. That part is a fact. We do not promise your kid ends up 30 minutes more active across the whole day. It might partly balance out.
158Strong
The word educational on an app means almost nothing. No standard backs it.
Hirsh-Pasek, Zosh, Golinkoff, Gray, Robb & Kaufman (2015), Psychological Science in the Public Interest 16(1), 3 to 34.
Strong (as a framework): the field's most-cited criteria paper for children's apps, from the same research program as ARC-02 and ARC-03
Who was studied: A consensus review for children, drawn from the science of how learning works. No single sample.
What they found: In 2015 about 80,000 apps called themselves educational or learning based. No science based standard decided who could use the word. The authors set one. Learning runs deepest when the child's mind is active, not just tapping. When nothing distracts. When the work means something. And when it is shared with people.
What it means for you: We refuse the word educational for our print packs unless they pass the same four tests. The four tests are also our design checklist. Minds on. Nothing distracting. Real meaning. Shared with a parent.
159Moderate
Most top educational apps failed the field's own quality tests.
Meyer et al. (2021), Journal of Children and Media 15(4), 526 to 548.
Moderate: careful content analysis, but it measures design features against a framework, not children's learning
Who was studied: 124 apps. They were the top 100 most downloaded educational apps on the two big stores, plus 24 apps preschoolers played most. This audit scored design. No children were tested.
What they found: Each app scored 0 to 3 on each of the four tests from FMT-04. 72 of 124, that is 58 percent, landed in the low quality range. Free apps scored worse than paid ones. The drag came from distracting add ons.
What it means for you: We can say most top listed educational apps fail the field's published tests. That is a claim about the shelf, not about any one rival. We never say apps teach children nothing. This study never measured learning.
160Background
Most parents have screen rules. Few can hold them every time.
Pew Research Center (October 2025), How Parents Approach Their Kids' Screen Time
National survey (§1)
Who was studied: 3,054 US parents of children age 12 and under.
What they found: 86 percent have rules about screen use. Only 19 percent enforce them all the time. 42 percent say they could do a better job. Among parents of 8 to 12 year olds that rises to 47 percent. Moms feel judged more than dads, 38 percent against 27 percent.
What it means for you: This is the problem in one entry. At the moment a parent hands over a screen, there is no ready swap that is just as fast and just as trusted. We never aim shame at the gap between a parent's rules and their follow through.
161Background
Young kids spend hours a day on screens. Not minutes.
Common Sense Media Census (2025; tween figures 2021 census as cited)
Census figures (§1)
Who was studied: US children ages 5 to 8. And tweens ages 8 to 12, from the 2021 census as cited.
What they found: Ages 5 to 8 average 3 hours 28 minutes of screen media a day. Tweens 8 to 12 average 5 hours 33 minutes of fun screen time a day.
What it means for you: The moment this product serves happens every day. It is not a rare occasion. And no copy from us ever inflates these census numbers.
162Moderate
Loot boxes work like gambling. They stay out. Full stop.
Drummond & Sauer (2018), Nature Human Behaviour (loot-box/gambling analysis).
Moderate: structural analysis, widely cited, but not an RCT in children
Who was studied: No child sample. The researchers analyzed how loot boxes are built and how they act on the mind.
What they found: Loot boxes meet the tests for gambling in both build and effect. Children who are exposed to gambling early face higher risk of gambling problems later.
What it means for you: This entry is a guardrail. No chance boxes appear in anything we make, paid or free. "It is not real gambling" is not an argument we accept.
163Checked
Teaching to a child's learning style does not work. We refuse to use it.
Pashler, McDaniel, Rohrer & Bjork (2008), Psychological Science in the Public Interest; Rogowsky, Calhoun & Tallal (2015)
Debunked (§6). Filed as a settled negative, §20 wing 7
Who was studied: Learners in studies built to test the style matching idea head on.
What they found: The idea says a visual learner learns best by seeing, and so on for each style. Studies that could truly test it found no such crossover. A later test built to the first paper's own rules found no link between a child's style and how well they understood in either mode.
What it means for you: We never route a pack by learning style. No survey question asks it. No copy rests on it. When a parent asks for styles by name, we route on what does work. Interests. Energy. Sense load. Who the child plays with.
164Checked
Paid surprise rewards are banned here, whatever they earn.
Zendle & Cairns (2018) and the loot-box literature; Danish Gambling Authority parent campaign (2026); Swedish regulator study
Cautionary literature, "equally clear" (§8); association flagged
Who was studied: Young players. The Swedish figure covers people who bought loot boxes before age 15.
What they found: Research ties paid surprise rewards in games to signs of gambling trouble in young players. In the Swedish study, 87 percent of those who bought loot boxes before 15 later showed risky gambling behavior. That is a link, not proof of cause, and we record it at that strength.
What it means for you: Chance lives inside the play, where a child can see and touch it. Dice. A shuffled draw. A twist. Rarity is printed in tiers, out in the open, and earned by playing. Every pack is complete as sold. No blind packs. No paid re rolls. No randomness in the buying, ever.
165Strong
The screen panic research is thin and tangled. We refuse to sell on it.
Odgers & Jensen (2020), Journal of Child Psychology and Psychiatry 61(3), 336 to 348 (Annual Research Review: Adolescent mental health in the digital age)
Strong (as a synthesis): an Annual Research Review in the field's leading child-psychology journal, by researchers who themselves study online risk (harvest grade, 2026-11-04)
Who was studied: Reviews and big studies of teens, smartphones, and social media. Note the flag. This research is not about 5 to 10 year olds, and not about screens in general.
What they found: The studies show a mix of small links. Some point up. Some point down. Many show nothing. The most careful studies, planned in advance, find effects too small to matter in practice. Even those cannot separate cause from effect.
What it means for you: Our voice stays pro balance. The science on screens and mental health is truly unsettled, and we say so. We never claim proof that screens are damaging children's mental health across the board. These screen entries cap the panic claims. They do not show screens are harmless for young kids, and they are not our argument against offering a screen free choice.
166Moderate
The claim that phones rewired a generation's brains is not backed by science. We refuse to repeat it.
Odgers (2024), Nature 628(8006), 29 to 30 (book review of Haidt, The Anxious Generation)
Moderate: authoritative venue and author, and consistent with NEG-03, NEG-05 and NEG-06, but a single scholar's review essay in an active dispute (harvest grade, 2026-11-04)
Who was studied: A scholarly book review in Nature. It weighs the reviewer's own research program and the work around it. Teens again, per the flag above.
What they found: The reviewer states it flatly. The book's repeated claim that digital tech is rewiring children's brains and causing an epidemic of mental illness is not supported by science. Hundreds of studies land on no effect, small effects, or a mix. Where timing links show up, troubled young people more often reach for the platforms first. Other scholars dispute this review. It is a critique, not a pooled analysis.
What it means for you: We decline fear based selling, and we can point to a reason at the top of the field. We never quote this review as proof that social media is harmless. It backs several platform reforms. And no copy here echoes rewiring brains or epidemic caused by phones.
167Moderate
Across 355,358 teens, screen use explained at most 0.4 percent of well being. We refuse to inflate that.
Orben & Przybylski (2019), Nature Human Behaviour 3, 173 to 182
Moderate: exemplary analytic transparency (all reasonable specifications reported), but observational self-report data throughout (harvest grade, 2026-11-04)
Who was studied: Three large teen datasets, 355,358 teens in total. The flag above applies. Teens, phones, and social media.
What they found: The link ran negative but tiny. Digital tech use explained at most 0.4 percent of the differences in teen well being. The authors judged that too small to base policy on. The data comes from watching, not experiments, and much of it is self report. The study caps the average link. It cannot show that no single child is harmed.
What it means for you: If we cite screen and well being numbers at all, we cite numbers this small. We never claim small amounts of screen time measurably damage well being across children. We never claim proven safe for every child either.
168Strong
The top US science body will not say social media causes teen health changes. Neither will we.
National Academies of Sciences, Engineering, and Medicine (2023), Social Media and Adolescent Health, National Academies Press, DOI 10.17226/27396
Strong (as consensus): the most authoritative US scientific body's considered position (harvest grade, 2026-11-04)
Who was studied: An expert committee review of the published research. Teens, per the flag above.
What they found: The committee states it plainly. Its review did not support the claim that social media causes changes in teen health across the population. The impact shifts by person, a mix of the risky, the helpful, and the plain everyday. Research shows small effects and weak links. The committee still urged protective steps and much more research.
What it means for you: Our settled line keeps both halves. Screens are not a proven population level cause of the youth mental health crisis. And children still deserve protected time for play, sleep, and family life. That second half rests on the play and activity entries, ARC-01, ARC-02, and ARC-12 to ARC-14. We refuse both distortions. Science says social media is destroying a generation. Science says there is nothing to worry about. The committee said neither.
169Strong
Birth order does not shape personality. We refuse to route on it.
Rohrer, Egloff & Schmukle (2015), PNAS 112(46), 14224 to 14229
Strong (as a null): the highest-powered test in the field, consistent across three countries and two designs; filed as a settled negative on the taxonomy audit of 2026-11-04
Who was studied: Three national panels of adults. 5,240 in the US, 4,489 in Great Britain, and 10,457 in Germany. The studies compared across families and within them.
What they found: Birth order showed no effect on outgoingness, emotional steadiness, agreeableness, carefulness, or imagination. The tests were strong enough to catch very small effects. A small slide in measured intelligence did show. Self reported intellect slid 0.1 of a standard step per birth spot.
What it means for you: The survey never asks about birth order. No pack copy calls a child the responsible firstborn or the wild youngest. The small smarts slide is not a personality claim, and we never treat it as one. Who is in the room to play still counts. That is social shape, and this entry does not touch it.
170Background
Families are tired of subscriptions and lose count of them.
Figures as recorded in brief (§4)
Recorded as design signal (§4); underlying surveys not named in brief
Who was studied: US adults and households, in surveys summed up in our project brief. The brief does not name the single surveys.
What they found: Families pay about $219 a month on subscriptions. They guess about $86. Roughly 41 percent say they are tired of subscriptions. The average home juggles about 11 of them.
What it means for you: Packs are buy once and own forever. New packs are add ons, not another monthly bill on your pile.
171Background
Play you can hold is growing fast in 2026.
Circana US toy reports (2025 full year; H1 2026)
Market data with an explicit honesty caveat (§3): claim the direction, not the growth rate
Who was studied: The whole US toy market, tracked by the Circana research firm. No single group of kids.
What they found: Toy dollars rose 17 percent in the first half of 2026. Units rose 12 percent. It was the strongest first half in six years. Games and puzzles led 2025 at $4.9 billion, up 37 percent. Much of the growth is licensed brands and adults buying for themselves.
What it means for you: Packs sit inside a growing shelf, not a shrinking one. We claim the direction only. Category growth is not our growth.
172Background
Parents already pay premium prices when science leads the pitch.
Lovevery, as reported in brief (§§2 to 3)
Existence proof (§3); company/trade reporting
Who was studied: Parents of kids ages 0 to 4 who buy Lovevery kits. A younger set of kids than ours. Figures come from company and trade reports.
What they found: The kits sell at $80 to $150 each. The company reached about $100 million in yearly repeat revenue by 2023. The pitch is research backed play.
What it means for you: A science first pack can carry a real price. That is proof the shelf exists. It is not proof of what our price should be.
173Background
Most download sellers earn little. A serious tier exists and takes time.
Etsy and KDP distributions as aggregated in brief (§15)
Directional (§15): seller surveys and aggregators, not official disclosures
Who was studied: Etsy sellers and self published authors, in seller surveys and roundups. These are directional figures, not audited ones.
What they found: The middle Etsy seller earns about $500 to $1,000 a year. About 70 percent of shops make under $100 a month. The top 10 percent clear $1,000 a month. Digital goods keep 85 to 95 percent margins. About 90 percent of self published books sell fewer than 100 copies ever.
What it means for you: Honest prices start from honest odds. A pack business is a slow build of many good small products. Nobody here promises you the big money.
174Background
A good quiz finishes and sells far better than plain browsing.
RevenueHunt, State of Product Recommendation Quizzes (2026 benchmark, 45M+ responses); ConvertFlow (2026, 2,120 campaigns)
Reasoned (Appendix A): vendor data with self-selected takers, direction agreed by both sources
Who was studied: More than 45 million quiz answers in one vendor study. Another looked at 2,120 campaigns. Both are company data, and quiz takers chose to take a quiz.
What they found: About 69 percent of starters finish a fit quiz. About 5.5 percent of finishers place an order. That is roughly 2.75 times a typical store rate. Quiz buyers spend 11 to 15 percent more.
What it means for you: The Sitter Test is the front door for a reason. It helps you land on the right pack fast. These are vendor numbers, so we treat them as a guide, not a promise.
175Background
A joke lands when something feels wrong and safe at the same time.
McGraw & Warren (2010), Psychological Science (benign violation theory)
Theory plus existence proof (§11)
Who was studied: General humor research on adults. No kids were studied.
What they found: Humor fires when a moment breaks a rule yet harms no one. Parent guilt about screens is full of such moments. Every parent thinks the forbidden thought. Naming it among friends makes it safe. One guilt themed parents' book hit number 1 on Amazon a month before it came out.
What it means for you: Our jokes aim at the moment, the tablet, and your inner voice. They never aim at your kid.
176Background
Funny ads get watched and liked. They cost a little trust.
Eisend (2009), meta-analysis, Journal of the Academy of Marketing Science (369 correlations)
Meta-analytic (§11)
Who was studied: A review that combined 369 results from advertising studies.
What they found: Humor lifted attention, good feeling, and the wish to buy. It also cut how trustworthy the source seemed, by a small amount. A joke with nothing behind it can steal the show. People recall the gag and forget the brand.
What it means for you: Every funny front door here has real studies right behind it. The science on this page is those studies. Jokes never share a sentence with a study claim.
177Moderate
A gift you do brings people closer than a gift you keep.
Chan & Mogilner (2017), Journal of Consumer Research 43(6), 913 to 931
Moderate: four experiments in a top journal, consistent mechanism; adult gift-givers, not grandparents-buying-for-children specifically (harvest grade, 2026-11-04)
Who was studied: Adults in four experiments, including friends giving each other gifts.
What they found: People felt closer after an experience gift than after an object gift. That held even when they did not share the experience. The closeness came from feelings during the activity. It did not come from the unwrapping or from seeming thoughtful.
What it means for you: A pack is a strong gift because it is something a kid does, again and again. Grandparents give time together, not one more object on the shelf.
178Moderate
People say experiences made them happier than things.
Van Boven & Gilovich (2003), Journal of Personality and Social Psychology 85(6), 1193 to 1202
Moderate: highly cited and replicated in direction, but substantially based on retrospective self-report; boundary conditions are real (harvest grade, 2026-11-04)
Who was studied: Adults in surveys and lab tests, looking back on their own buys.
What they found: People rated experience buys as the happier ones. In the lab, just thinking about an experience buy felt better. Later work found the edge shrinks for lower income buyers and for people who prize things.
What it means for you: Gift copy can honestly talk about doing over owning. It speaks to the giver's own joy. It never promises how the kid will feel.
179Moderate
Givers and receivers want different gifts.
Galak, Givi & Williams (2016), Current Directions in Psychological Science 25(6), 380 to 385; Givi, Birg, Lowrey & Galak (2023), integrative review, Journal of Consumer Psychology 33(3), 529 to 545
Moderate: reviews, not new data, but they organize a consistent experimental literature and generate the testable predictions the primary studies confirm (harvest grade, 2026-11-04)
Who was studied: Reviews that sum up many gift experiments. The people in those experiments were mostly adults.
What they found: Givers aim at the handover moment. They chase surprise and a big reaction. Receivers care about life with the gift. They want useful, flexible, and easy. That one gap explains a long list of gift misses.
What it means for you: Judge our gift pages by the receiver's test. Will the family use it easily and often, with no extra work for the parent?
180Moderate
People like the gift they asked for more than a surprise.
Gino & Flynn (2011), Journal of Experimental Social Psychology 47(5), 915 to 922
Moderate: five-study package, consistent; adult samples, mostly non-child gifts (harvest grade, 2026-11-04)
Who was studied: Adults giving and receiving gifts, across five studies.
What they found: Receivers were more thankful for gifts they had asked for. Givers wrongly thought a surprise looked just as thoughtful. One clear request worked best of all. Receivers also liked cash more than givers guessed.
What it means for you: A wishlist is not rude. It is how a grandparent buys the exact right pack. The parent asks. The grandparent buys. The thanks run higher.
181Moderate
A higher price does not buy more thanks.
Flynn & Adams (2009), Journal of Experimental Social Psychology 45(2), 404 to 409
Moderate: a clean, much-cited asymmetry; verification status in this harvest is index-level (harvest grade, 2026-11-04)
Who was studied: Adults giving and receiving birthday gifts, in lab studies and memory checks.
What they found: Givers expected thanks to rise with price. Receivers' thanks did not follow price at all.
What it means for you: No giver needs to stretch to the priciest pack to be appreciated. A fairly priced pack that gets used earns the thanks.
182Moderate
Givers pick the fancy one. Receivers prefer the easy one.
Baskin, Wakslak, Trope & Novemsky (2014), Journal of Consumer Research 41(1), 169 to 182
Moderate: large study package in a top journal, with a field study; populations are not gift-buying relatives of 5 to 10-year-olds (harvest grade, 2026-11-04)
Who was studied: Adults and young adults in eight classroom studies, plus one study of friends giving real gifts.
What they found: Givers chose the grand option, like a certificate for a fancy far away restaurant. Receivers preferred the good one nearby. Receivers even read the handy gift as the more caring one.
What it means for you: Gift pages lead with easy. Starts in minutes. No setup. No extra buys. Fits a normal evening. Showy comes last, if at all.
183Moderate
Gifts often land worth less to the receiver than they cost.
Waldfogel (1993), American Economic Review 83(5), 1328 to 1336
Mixed: a famous result with serious published counter-results; the safe residue is "uninformed non-cash gifts often miss," not a percentage (harvest grade, 2026-11-04)
Who was studied: Yale students rating their own holiday gifts. One group had 86 students.
What they found: Receivers valued gifts at about 66 to 90 percent of what givers paid. Gifts from grandparents, aunts, and uncles scored worst, near 63 to 64 percent. Friends and partners scored best. Later studies asked in other ways and found a much smaller loss, or none.
What it means for you: The miss risk is highest for distant relatives, our most common gift buyers. Asked for gifts and experience gifts dodge most of that loss. We never quote a third of gift value as destroyed. The number depends on how you ask.
184Moderate
People pay extra for one flat price, even when per use is cheaper.
Lambrecht & Skiera (2006), Journal of Marketing Research 43(2), 212 to 223
Moderate: strong revealed-preference data (real bills, not intentions), but in internet tariffs, and it compares flat vs per-use, not one-off vs subscription directly (harvest grade, 2026-11-04)
Who was studied: Internet customers in four analyses of real bills linked to surveys. All adults.
What they found: Many users picked a flat rate while a per use plan would have cost less. They liked dodging bill shocks. They disliked watching a meter run. They also overestimated their own use. Flat rate fans did not quit more, even while overpaying.
What it means for you: One clear price with no meter running is worth real money to families. A subscription is also a flat price, so this study backs flat over metered only. It does not settle buy once versus subscribe.
185Moderate
People use a thing most right after they pay for it.
Soman & Gourville (2001), Journal of Marketing Research 38(1); Gourville & Soman (2002), Harvard Business Review 80(9)
Moderate: a well-known program with field data, cutting against simple buy-once advocacy; exact 2001 percentages are index-level here (harvest grade, 2026-11-04)
Who was studied: Theater and ski pass buyers, plus gym members, in real purchase records. All adults.
What they found: Use peaks while the payment feels fresh. It fades as the payment is forgotten. Gym members who paid monthly showed up more steadily than members who prepaid a year. Bundle holders left more tickets unused than people who bought one ticket at a time.
What it means for you: A buy once pack needs its own reminders built in. Quick early wins and a daily cue keep it alive. Buying is not the same as using, and we design for the using.
186Strong
A long or hard survey gets lazy answers.
Krosnick (1991), Applied Cognitive Psychology 5(3), 213 to 236.
Strong (as theory): the foundational, still-standard account of survey response quality
Who was studied: Survey experiments with adults in general.
What they found: Answering well takes work. A person has to read the question, dig up what they know, weigh it, and report it. When the survey is hard, or the person is tired or not motivated, they cut corners. They pick the first answer that sounds fine. Or they agree with whatever is put in front of them. Or they skip the thinking and say they do not know. The risk grows with every question added.
What it means for you: Our survey stays at eleven questions. Each one asks only what a parent already knows. The questions that matter most come first.
187Moderate
Say a survey takes 30 minutes and fewer people start. Answers also get worse near the end.
Galesic & Bosnjak (2009), Public Opinion Quarterly 73(2), 349 to 360.
Moderate: a real experiment on stated length and position effects; one panel, one country context
Who was studied: Adults in an online panel experiment.
What they found: The stated length was set at 10, 20, or 30 minutes. The longer the stated length, the fewer people started and finished. Answers late in a survey came faster. They were shorter and more alike. People also skipped more late questions.
What it means for you: We say the true length up front. Eleven questions, about three minutes. Questions the fit depends on come before any extras. We never pad the survey with nice to have questions.
188Thin
One careful test found the stated length changed nothing.
Lugtig & Luiten (2021), field experiment on stated survey length (Netherlands).
Thin (as recorded here): included deliberately as the counterweight; verification status is weaker than ASK-02's
Who was studied: Dutch survey respondents in a field experiment.
What they found: Telling people the survey's length had no effect on who took part or who dropped out. That runs against ASK-02 above.
What it means for you: We keep the survey short because short is safe and cheap. We do not promise that shortness alone lifts how many parents finish. Read together, the two studies grade the length claim as mixed.
189Moderate
Survey design is a settled craft. Follow it. Do not improvise.
Dillman, Smyth & Christian (2014), Internet, Phone, Mail, and Mixed-Mode Surveys: The Tailored Design Method (4th ed.), Wiley, ISBN 9781118456149.
Moderate: the standard reference in the field, but a methods synthesis, not a single effect study; specific prescriptions (one question focus at a time, consistent visual layout, plain wording, answer options that are mutually exclusive and exhaustive) carry varying strength of experimental backing
Who was studied: Decades of survey experiments across general populations. This is the field's standard methods book.
What they found: People answer most when three things happen at once. The cost to them goes down. The benefit goes up. Trust goes up. The book's working rules include plain wording, one idea per question, a steady layout, and answer choices that cover the ground without overlap.
What it means for you: Our eleven questions are built to those published rules. We can say the survey was designed to the standard. We never claim the standard proves our recommendation is right. Good design cuts error. It does not bless the rule that reads the answers.
190Moderate
Parents and children agree on what can be seen. They agree far less on feelings.
Eiser & Morse (2001), Quality of Life Research 10, 347 to 357.
Moderate: systematic review, consistent pattern, in the health-QoL domain rather than play preference
Who was studied: A review of studies comparing parent and child reports. It covered children with and without long term health conditions.
What they found: Agreement ran by topic. It was higher for physical and visible parts of a child's life. It was lower for feelings and social life. Parents of ill children agreed more with them than parents of healthy children did.
What it means for you: We ask you about facts you can watch. What your child does. How long they stay. What they return to. We never ask you to report your child's inner feelings as if you were reading them off a gauge.
191Moderate
At ages 5 to 8, parents and kids agreed only weakly about the child's own life.
Cremeens, Eiser & Blades (2006), Health and Quality of Life Outcomes 4, 58.
Moderate: one well-conducted study, directly in the product's age band, on a validated instrument
Who was studied: 149 healthy children in three age bands from 5.5 to 8.5 years. And 103 of their parents.
What they found: Parent and child scores on a standard quality of life scale matched only weakly. The match ran from 0.02 to 0.23, where 1 would be perfect. Parents and children differed on every part of the scale. A parent's own quality of life also colored the score they gave their child.
What it means for you: What the survey gives you is labeled as based on your answers about your child. That is a parent's view, and we say so. Where we can, your child's own reaction settles fit. Does the child pick it up again?
192Strong
No single person sees the whole child. Not even the child.
Achenbach, McConaughy & Howell (1987), Psychological Bulletin 101(2), 213 to 232.
Strong (for the pattern): the field-defining meta-analysis on informant discrepancy; discrepancies are now understood as partly reflecting genuinely situation-specific behavior, not just error
Who was studied: A review of 119 studies with 269 samples. Ages ran from 1.5 to 19 years.
What they found: Two similar watchers, like two parents, matched at about .60. A parent and a teacher matched at about .28. A child's own report matched other people's at about .22. Kids ages 6 to 11 matched others more than teens did. Part of the gap is real. Children act differently in different places.
What it means for you: Our words stay humble. You get a starting recommendation, not a verdict. And swapping or adjusting after your child tries the pack is cheap and built in. Eleven parent answers are never the whole picture here.
193Moderate
What people say they would pay runs about a third above what they do pay.
Murphy, Allen, Stevens & Weatherhead (2005), Environmental & Resource Economics 30(3), 313 to 325.
Moderate: solid meta-analysis, but in environmental valuation, not consumer product fit
Who was studied: A review of 28 studies with 83 comparisons. Each one set what people said against what they did with real money, using the same method both times.
What they found: The median overstatement was about 1.35 times the real value. A few cases overstated by far more. Asking people to choose between options cut the bias. The numbers also moved a lot with how the study was modeled.
What it means for you: We treat every stated preference as a signpost, never a fact. That includes answers to our own survey. We check them against real behavior. Did the child finish? Did they choose it again? Did the parent buy?
194Strong
A real screening test earns that name with tens of thousands of children behind it.
Squires, Twombly, Bricker & Potter (2009), Ages & Stages Questionnaires, Third Edition (ASQ-3), Brookes Publishing.
Strong (for the boundary claim): the contrast is structural, not a matter of effect-size dispute
Who was studied: The Ages & Stages screening tool covers children from 1 month to 5.5 years. Its accuracy was checked in a sample of 15,138 children, per the publisher.
What they found: The tool runs 21 age based forms with 30 set questions for each age step. It publishes cut off scores. Its catch rate runs 75 to 100 percent by age step. Its clear rate runs 70 to 100 percent. Later reviews find those numbers swing widely by age, place, and skill area. Even a real screening tool lands at moderate accuracy.
What it means for you: Our tool is called the Sitter Test. It recommends a starting point. That wording is chosen on purpose, and this is the reason. We never say the quiz assesses development, checks readiness, or spots delays. That is the clearest line in this whole group.
195Moderate
Explaining a pick can make the pick worse, even when it feels better.
Tintarev & Masthoff (2012), User Modeling and User-Adapted Interaction.
Moderate: peer-reviewed synthesis with experiments, in consumer recommenders, not parent/child products
Who was studied: A review plus four experiments with adults. The tests used movie and camera recommenders.
What they found: An explanation can aim at many things. A better decision. Satisfaction. Trust. Being able to check the work. These aims can clash. Tailoring the explanation to the person made decisions worse in the tests, even where it may have raised satisfaction.
What it means for you: You get your match in a few short lines. It shows the answers you gave and the one main reason we picked this pack. It is built so you can check it and tell us where it is wrong. It is not built to persuade you. And your match is never offered as proof the pick is right.
196Moderate
A fair amount of explanation rebuilds trust. A flood of it drains trust again.
Kizilcec (2016), Proceedings of CHI '16, 2390 to 2395, DOI 10.1145/2858036.2858402 (DOI as printed in the paper itself).
Moderate: a genuine field experiment, but one study, adult learners, grading context
Who was studied: 103 adult learners in an online course grading system. They averaged about age 37.
What they found: Students who got a lower grade than they expected trusted the system less. A middle amount of openness, how the grading worked, brought trust back. The highest openness, which also dumped outcome data, wore trust back down. When the grade matched what a student expected, openness changed nothing.
What it means for you: Your match stays at one short paragraph. It tells you how we picked. We matched on the two things you said matter most. It does not dump every answer, weight, and rule. This matters most when your pack disappoints you.
197Strong
Kids need an hour of active play a day.
Bull et al. (2020), British Journal of Sports Medicine 54, 1451 to 1462 (World Health Organization 2020 guidelines on physical activity and sedentary behaviour).
Strong as an authoritative guideline; the underlying evidence for sedentary limits is Low certainty by WHO's own grading, both facts travel together
Who was studied: The World Health Organization guidelines for ages 5 to 17.
What they found: Kids should average at least 60 minutes a day of active play that gets the heart going. Sitting time should be kept down, screen time most of all. The WHO sets no exact screen limit for this age.
What it means for you: A pack helps fill that active hour. We never quote a WHO screen cap for your kid's age. There is none.
198Strong
US guidance asks for the same active hour.
U.S. Department of Health & Human Services (2018), Physical Activity Guidelines for Americans, 2nd edition, as presented by the CDC.
Strong as an authoritative statement of US guidance
Who was studied: US health guidance for ages 6 to 17.
What they found: Kids need 60 minutes or more of active play each day. Three days a week should include hard effort and work that builds muscle and bone. US guidance sets no screen time number.
What it means for you: US families can use the hour as the target. Nobody official in the US gives a screen cap to quote.
199Moderate
Starting with real objects and fading step by step to symbols helped children carry maths learning to new problems.
Fyfe, McNeil and Borjas (2015), Learning and Instruction
Moderate: in band, three experiments, one research group
Who was studied: Second and third graders, about 7 to 9 years old.
What they found: In three experiments, starting with concrete materials and fading to symbols beat concrete only, symbols only, and the reverse order. The fading group transferred what they learned to new and harder problems.
What it means for you: Maths missions in a pack can start with real objects and fade to symbols in steps. That order is the part the studies tested.
200Strong
A year of worked examples with self explanation prompts brought no overall gain in algebra readiness.
McGinn, Booth and Huyghe (2025), Journal of Experimental Child Psychology
Strong (as a null): large randomized trial, in band at its lower part
Who was studied: Fourth and fifth graders in 58 classrooms in the United States, about 9 to 11 years old.
What they found: The randomized trial of the MathByExample program found no significant overall effect on algebra knowledge or readiness to learn more. Gains showed only in narrower analyses, for children who worked through many worksheets and answered many prompts.
What it means for you: This is a caution we keep on the list. A pack never claims that worked examples help children this age learn maths, stated flatly.
201Moderate
How well young children carry out spoken instructions tracks working memory. Repeating the words back does not.
Gathercole, Durling, Evans, Jeffcock and Stone (2008), Applied Cognitive Psychology
Moderate: in band at its lower end, clean task match
Who was studied: Children aged 5 and 6.
What they found: Children heard instructions built from a sequence of objects. Some carried them out and some repeated the words. Accuracy at carrying out, not at repeating, was strongly linked to working memory.
What it means for you: Multi step missions work best one step at a time, with the child doing each step as it comes. We do not claim that following steps trains planning or self control.
202Moderate
Children follow instruction sequences better when they act out each step as it is given, and act again when they recall it.
Jaroslawska, Gathercole, Logie and Holmes (2016), Memory and Cognition
Moderate: two studies, one research group, in band
Who was studied: Children aged 7 to 11 in one study and 7 to 9 in another.
What they found: In two experiments, doing each instruction as it was presented beat hearing, reading, or repeating the words. Acting the steps out again at recall helped too. Working memory was closely linked to following instructions in real and screen based tasks.
What it means for you: Sequence missions use a step by step doing format for this reason. The claim is about following instructions well, not about growing working memory over time.
203Moderate to strong
When grown-ups point to print and talk about it during shared reading, preschoolers gain more print knowledge than from picture focused reading.
Justice and Ezell (2002); Justice, Kaderavek, Fan, Sofka and Hunt (2009)
Strong for preschool: the claim above age 5 rests on follow up outcomes, not on a trial at ages 7 to 10
Who was studied: Children ages 3 to 5. The trials ran at age 4, with follow up into the early school years.
What they found: Print focused shared reading beat picture focused reading on print awareness. A 30 week trial in 106 children produced larger gains on three print knowledge measures. A 30 week trial in 550 four year olds moved literacy skills measured two years later.
What it means for you: Letter and print missions build in grown-up print talk, pointing at words while reading together. The strong proof is at preschool age, and the page says so.
204Moderate
Print rich play helped print awareness mainly when a grown-up joined in and talked about the print.
Neuman and Roskos (1993), American Educational Research Journal
Moderate and mixed: one classic preschool study, one very small in band study, one in band caution
Who was studied: Preschoolers in the classic study. Two smaller studies worked with children ages 5 to 6.
What they found: Play settings enriched with print helped on print tasks only with active adult engagement. It did not move understanding of what print is for. A small eight week program at ages 5 to 6 raised print awareness, and a gamified picture book trial found small effects.
What it means for you: Print play in a pack comes paired with grown-up talk about the print. Print props on their own are not the active ingredient.
205Moderate
Between about 6 and 10, children get better at riddles and jokes that turn on words with two meanings. A bigger vocabulary goes with better understanding.
Purser, Van Herwegen and Thomas (2020), Journal of Experimental Child Psychology
Moderate: developmental and correlational, in band
Who was studied: Children ages 4 to 11, with the school year studies covering ages 6 to 11.
What they found: Higher vocabulary was independently linked to better humour comprehension. Only children age 8 and older reliably connected understanding a joke to laughing at it. Riddle comprehension developed in an order, with sound and word meaning jokes first and idioms last.
What it means for you: Riddle and double meaning play is matched to the older end of the age range. We do not claim word play teaches vocabulary or reading.
206Thin
Children who make more jokes in play tend to understand other minds better and get on warmly with siblings.
Paine, Karajian, Hashmi, Persram and Howe (2021), Social Development
Thin to moderate: observational and correlational only
Who was studied: Children age 5 playing with siblings, and 110 first born children with an average age of about 7.
What they found: Children with a better understanding of minds produced more humour in sibling play. At about age 7, word play with a sibling went along with pretend play alone, and humorous sound play went along with emotion understanding. These are associations, not causes.
What it means for you: Silly partner play is framed as social play, and humour is treated that way in packs. Nothing here shows that joking practice builds language or mind understanding.
207Moderate to strong
Teaching children the parts of a story, with practice retelling, improves how well they understand and tell stories.
Pico, Prahl, Biel, Peterson and colleagues (2021), Language, Speech, and Hearing Services in Schools
Strong for the instructional claim at program dose: support is strongest at age 5 to 6 and more mixed across the wider pool
Who was studied: Preschool and elementary children in the United States, pooled across 26 studies. One trial covered 686 kindergartners.
What they found: Programs that taught story parts directly, with supports and retelling practice, improved story comprehension and story telling, with effects around half a standard deviation. A 14 week randomized trial raised every measured outcome, including retells.
What it means for you: Story missions can teach story parts and build in retelling practice across a pack. No single session is promised to do this, and a cliffhanger pause by itself teaches nothing.
208Checked
Whether pretend play or drama causes gains in seeing another person's view is not settled.
Goldstein and Lerner (2018), Developmental Science; Celume, Goldstein, Besancon and Zenasni (2020)
Mixed: the strongest design is null for the claim and the positives do not replicate each other
Who was studied: Children from age 4 to about 10 across four reports, with the oldest groups sitting just above the band.
What they found: The blinded randomized trial found drama games improved emotional self control only, with no gain in empathy or understanding of minds. Smaller studies with weaker designs each found a gain on one measure. They do not replicate each other.
What it means for you: Role play missions carry only a weak, hedged sentence, naming weeks of guided play and the unsettled state of the evidence. The strong claim is on the refused list.
209Moderate
Five weeks of daily fantastical pretend play improved executive function scores in 3 to 5 year olds.
Thibodeau, Gilpin, Brown and Meyer (2016), Journal of Experimental Child Psychology
Moderate for its own finding: below band and a different outcome from perspective taking
Who was studied: 110 children ages 3 to 5, mostly below the 5 to 10 band.
What they found: In a randomized trial, only the fantastical pretend play group improved on executive function measures. The authors frame the result as one of many routes to the same outcome.
What it means for you: This entry sits beside the pretend play missions as context, with its age limit printed. It licenses no claim inside the 5 to 10 band, and nothing about seeing another person's view.
210Moderate
Carrying an object steady and level with both hands while walking is genuinely hard for children, and younger children find it harder.
Hung, Meredith and Gill (2013), Gait and Posture
Moderate: direct task match, consistent across groups
Who was studied: Children in groups spanning ages 4 to 16, including 5 to 6 and 7 to 9 year olds.
What they found: Children carrying a box steady showed less coordination between the hands, a less level hold, and shorter strides, worst in the youngest group. A motor second task changed walking more than a thinking second task.
What it means for you: A tray carry mission is framed as a task that practices balance and body control. The tray is the hard part, not decoration. One session is not claimed to improve balance.
211Moderate to strong
Balance and movement skills improve with repeated practice over weeks in school age children.
Gebel, Lesinski, Behm and Granacher (2018), Sports Medicine
Moderate to strong for trainability over weeks: dose and age pattern are uneven and the age 6 to 7 null stands in the record
Who was studied: Children and young people across 17 balance trials and 33 school intervention studies, including ages 6 to 12.
What they found: Balance training produced moderate to large effects across trials. School movement skill programs improved overall proficiency, and motor skill teaching improved fundamental skills where free play controls did not. One short program at age 6 to 7 found no significant gain.
What it means for you: Movement missions are framed as repeated practice across a pack. One session is never said to build balance, and effects are not uniform at every age.
212Thin
One 12 minute freeze dance with changing rules lifted executive function scores right after play, in preschoolers. It did not move inhibition.
Preston, McClelland, Craig, Herbst and Golinkoff (2025), Early Childhood Research Quarterly
Thin to moderate: single study, below band, immediate effects only
Who was studied: 111 children with an average age of just under 5, below the 5 to 10 band.
What they found: The freeze dance group showed the greatest immediate improvement on executive function tasks, clearest on a working memory task. A secondary summary of the same study reports no effect on the inhibition measure, and the lead author states that how long the improvement lasts is not clear.
What it means for you: Any freeze game claim in a pack prints its age and durability limits beside it. Lasting change and self control claims are refused.
213Moderate
Understanding money builds in stages across the early school years, and a joined up grasp of buying and selling often arrives only at about age 11.
Berti and Bombi (1981), Child Development; Jahoda (1979)
Moderate: developmental stage work, older studies, consistent shape
Who was studied: 80 Italian children ages 3 to 8, tested twice over one year, and 120 children ages 6 to 12.
What they found: Money understanding moved through six stages, ending in strict price correspondence and correct use of change. The youngest children did not see that a shopkeeper pays for goods, and a joined up grasp of shop transactions arrived at about age 11.
What it means for you: Shop and pricing play is framed as practice inside a skill that is still developing. A pricing mission is never said to teach coin value, correct pricing, or change.
214Moderate
Children learn to measure by counting how many of one unit it takes to fill, cover, or match something, and the skill builds step by step.
Sarama, Clements, Baroody and colleagues (2021), AERA Open
Moderate: a controlled trial for length and trajectory work for volume: the volume leg is thinner than the length leg
Who was studied: 189 kindergartners, about age 5 to 6, and longitudinal cohorts followed from prekindergarten into grade 5.
What they found: Kindergartners taught length measurement in learning trajectory order learned more than a reverse order group, and both taught groups beat usual teaching. The four year study mapped how length, area, and volume thinking grows, including volume built on filling a space with units and counting them.
What it means for you: Measurement missions count units and run in trajectory order. One session of cup play is not said to teach volume, and the length trial is not borrowed for capacity claims.
215Thin
Four year olds can learn to compare and sort objects by how heavy they feel in the hand.
Wang, Williamson and Meltzoff (2015), Frontiers in Psychology
Thin for this product: one study, below band, about comparison and sorting, not estimation
Who was studied: Children age 4 only, in the United States and China, below the 5 to 10 band.
What they found: Children who watched an adult heft identical looking objects and sort them into two bins by weight were more likely to sort by weight themselves. They carried the rule to new objects.
What it means for you: Weighing play is framed as heft and compare. Nothing here supports claims about guessing weights, estimation, or transfer to maths.
216Thin
Estimation and maths both improved across the first school year. Growth in estimation was not tied to growth in maths.
Muldoon, Towse, Simms, Perra and Menzies, longitudinal study across the first school year (Lancaster University repository copy)
Thin to moderate: longitudinal, in band at its floor, about number estimation and not weight
Who was studied: 99 children age 5, across their first school year.
What they found: Estimation quality, counting, and maths ability were correlated and all improved. Changes in estimation were not associated with changes in maths ability. The authors argue estimation is not uniquely privileged over counting skill.
What it means for you: This is a caution against borrowing number estimation prestige for a weighing mission. Estimation practice builds maths is a claim we do not print from this study.
217Moderate
Children infer causes from contact and from patterns of evidence, and they explore more on their own when the evidence is unclear.
Schlottmann (1999), Developmental Psychology
Moderate: the one in band study is a caution, and the supporting studies sit below the band
Who was studied: Children ages 5 to 10 in the contact experiments, with supporting studies in preschoolers.
What they found: At ages 5 and 7, children chose the cause that happened right before an effect over the real mechanism when the two pointed different ways, so timing can override mechanism knowledge. Preschoolers used patterns of evidence to override a starting assumption, and explored more when evidence was unclear. The opened copy of the 1999 study is the author preprint.
What it means for you: Build and knock down play can name what touched what, and in what order. Demolition teaches cause and effect is a claim we refuse.
218Moderate
When a grown-up asks open questions and adds detail while talking about a shared past event, the child recalls that event in more detail later.
Langley, Coffman and Ornstein (2017), Journal of Cognitive Development
Moderate: real memory support, with the topic and direction conditions attached
Who was studied: Children assessed at ages 3, 5, and 6. The age 5 and 6 assessments sit inside the band.
What they found: In a large longitudinal study, mothers with a more elaborative reminiscing style had children with stronger memory for their own past events, at the time and later. The style was also linked to strategy use on deliberate memory tasks. The design is longitudinal and correlational, not a training trial.
What it means for you: Reminiscing missions are built on the grown-up asking and adding detail about an event the two of them shared. The claim runs in that direction, about shared events, and not to interviews about present topics.
219Moderate
Hearing the same story again, with brief explanations of its words, helps young children say and know those words, not just recognise them.
Sénéchal (1997), Journal of Child Language; Biemiller and Boote (2006)
Moderate: in band support for rereading with explanation: the expressive practice leg sits below the band
Who was studied: Children ages 3 and 4 in the first study, and kindergarten to grade 2, about ages 5 to 8, in the rereading trials.
What they found: Answering questions during repeated readings helped expressive vocabulary more than receptive. Repeated reading alone gained about 12 percent of taught word meanings. Adding brief explanations during rereading raised that to 22 percent, and to 41 percent with more explanation and review.
What it means for you: Story missions can repeat a frame with words already met, while a grown-up explains any new word. Slotting new words into a repeated frame is the variation the evidence warns against.
220Thin
An origami based program improved spatial vocabulary and lowered maths anxiety in grades 3 to 5.
Ridgley, Geary and colleagues (2025), Frontiers in Education
Moderate to thin: in band for the program study, below band for the developmental study
Who was studied: 179 elementary students in the program trial, with follow ups in grades 3 to 5, and preschoolers in Japan in the developmental study.
What they found: The origami program improved spatial vocabulary and reduced maths anxiety, with possible geometry gains and no significant arithmetic gains. In preschoolers, precise folding improved sharply around age 4, and model making skill was predicted by folding precision and figure recognition.
What it means for you: Origami is framed as spatial language and precision play. Planning and self control claims for folding appear in neither study and are not made.
221Moderate
Children ages 5 to 7 learned mass measurement through a short sequence of lessons built on hefting, balance scales, and units.
Cheeseman, McDonough and Ferguson (2014), Mathematics Education Research Journal
Moderate: in band, one design experiment, no control group
Who was studied: 119 Year 1 and Year 2 children, about ages 5 to 7.
What they found: Across five lessons of rich mass experiences, with interviews before and after, the majority of children progressed from nonstandard units toward standard units and instruments.
What it means for you: A mass measurement sequence can be taught across lessons in a pack. Estimation claims for a heft and guess game are not licensed by this study.
222Moderate
Judging how heavy something is by watching someone else lift it is still developing at 6 to 10, and has not reached adult accuracy by age 10.
Sciutti, Patane and Sandini (2019), PLOS ONE
Moderate: in band, one study, judgment by watching rather than hefting
Who was studied: 63 children at ages 6, 8, and 10, plus 21 adults.
What they found: Children judged the weight of bottles from 100 to 400 grams by watching lifting videos. Six year olds could tell heavier from lighter. Accuracy rose with age and had not reached adult levels by 10, and body size predicted accuracy better than age.
What it means for you: This entry prints as a developmental caution beside any weight judgment play. Watching or guessing is not claimed to build accurate estimation.
223Moderate to strong
Children remember instructions better when they see the actions first.
Waterman et al. (2017), "Do actions speak louder than words?"
Moderate to strong for the direction at ages 6 to 10: three experiments, with the boundary conditions measured rather than assumed
Who was studied: Children ages 6 to 10, across three experiments with 81, 81, and 64 children.
What they found: Children remembered instructions better when the actions were acted out. Doing the actions while hearing the instructions hurt recall when the action set was large, but watching a demonstration first improved recall, and a smaller action set turned doing it yourself positive.
What it means for you: Printed picture steps are the paper form of a demonstration. One action at a time, the child doing each step as it arrives, and small action sets per instruction.
224Moderate
A child can hold about two instructions at 5 to 6, three at 7 to 9, and four by 10 to 12.
Alloway & Alloway (2015), Understanding Working Memory; Gathercole's Working Memory Test Battery for Children standardization
Moderate: a practitioner rule of thumb that faithfully summarizes a standardized research program; the step counts were not produced by one experiment
Who was studied: School-age children in the Gathercole and Alloway working memory research program, including the standardization sample for the Working Memory Test Battery for Children.
What they found: The classroom rule: a 5 to 6 year old remembers about two instructions, a 7 to 9 year old manages three, a 10 to 12 year old copes with four. Inside a single age year, working memory varies by the equivalent of several years, so the step count is a ceiling set for the lower third of a band, not an average to design to.
What it means for you: Step budgets in pack design specs: two steps at 5 to 6, three at 7 to 8, up to four at 9 to 10. Steps are numbered and the plan stays visible, so the paper holds what memory does not.
225Moderate
Handwriting is slow across the whole band, and composing is slower than copying.
Chu (2007) copying speed norms and Graham, Berninger, Weintraub & Schafer (1998), Journal of Educational Research, as carried in practitioner guidance
Moderate: two independent norm traditions converge on the range; the numbers reach us through guidance pages rather than the primary norming papers
Who was studied: School children ages 6 to 11 in the norming samples behind two guidance summaries.
What they found: Copying speeds: about 4 words a minute at age 6, about 6 at age 7, about 7 at age 8, about 9 at age 9, about 10 at age 10, about 12 at age 11. Grade norms agree on the range, and exact values vary by test and country. Composing, where the child must also decide what to write, is slower than copying.
What it means for you: Required writing budgets per pack: under about 15 words at 5 to 6, about 30 to 50 at 7 to 8, about 100 at 9 to 10. Drawing, circling, matching, cutting, and moving objects carry the load instead of writing.
226Moderate
Fine motor milestones set the craft ceiling by band.
Kid Sense Fine Motor Development Chart, as distributed in the Vancouver Coastal Health paediatrics resource set
Moderate: a clinical milestone chart in health service use; milestones describe what most children can do, not a tested training effect
Who was studied: A developmental milestone chart covering ages 5 to 8; chart norms, not a single study sample.
What they found: At 5 to 6, children cut simple shapes, copy a triangle, use a three-finger grasp, and paste and glue. At 6 to 7, they form most letters and numbers correctly, with good writing endurance. At 7 to 8, they keep legibility for a whole story and cut neatly and precisely.
What it means for you: Cutting and assembly demands are set per band: simple shapes and thick lines at 5 to 6, detailed cutting by 7 to 8. Anything fiddly is pre-cut for the youngest band.
227Background
School math sets expectations the bands can play on.
Common Core State Standards for Mathematics (2010), official standards text
Strong as a statement of curriculum expectations; no grade as developmental evidence
Who was studied: US school children by grade: grade 1 about ages 6 to 7, grade 2 about 7 to 8, grade 3 about 8 to 9.
What they found: Grade 1 adds and subtracts within 20, fluently within 10. Grade 2 adds and subtracts within 100 and works with dollar bills and coins. Grade 3 multiplies and divides within 100 and solves two-step word problems. These are curriculum expectations: a ceiling for teaching, not a description of what a child can already do.
What it means for you: Money play is pitched as a strength at 7 to 8: mixed coins, making amounts, simple change from a dollar. No core mechanic rests on times tables below the top of the 7 to 8 band, and no curriculum skill is ever a gate.
228Moderate
Creative play and creativity move together across childhood, most strongly at ages 3 to 7.
Rantina, Nurani & Pujiastuti (2026), F1000Research
Moderate for the association and its age gradient; thin for any causal reading; a single recent synthesis
Who was studied: A meta-analysis of 78 studies of creative play and creativity.
What they found: The overall association was g = 0.62. By age it was 0.74 at ages 3 to 7, 0.61 at ages 8 to 12, and 0.48 at ages 13 to 18. By play type, dramatic play showed 0.71, constructive play 0.65, and digital play 0.52. Most studies in the pool were correlational, and the strongest causal claims for pretend play specifically are not supported.
What it means for you: Dramatic and constructive play stay at the center of pack design across all three bands, including 9 to 10, where the association remains substantial. We never print that play makes children more creative.
229Moderate
Breaking school work into near, clear subgoals, with progress shown, helped children keep going and learn more.
Bandura and Schunk (1981), Journal of Personality and Social Psychology; Schunk (1983)
Moderate: two in band studies on school tasks, plus one above band direct test
Who was studied: Children ages 7 to 10 in the two in band studies, and sixth graders in the third.
What they found: Near subgoals produced faster progress, higher mastery, higher confidence, and more interest, while a far away goal had no demonstrable effect. Children who monitored their own progress, or whose progress an adult monitored, showed higher confidence, skill, and persistence than children with no monitoring.
What it means for you: School like tasks can use near subgoals and visible progress, which is also how Mission 24 in The Witching Hour prints its claim. Deadline claims and chore claims are not licensed by these studies.
230Moderate
Time pressure helps some children and hurts others. A visible timer calmed a timed maths test without raising scores.
Plass and Hill (1986), Developmental Psychology; Hallez and Vallier (2025)
Moderate (as a caution): in band, and the two studies point against any blanket deadline claim
Who was studied: 155 third and fourth graders, about ages 8 to 10, and 44 children ages 7 to 9.
What they found: Highly test anxious boys performed poorly under time pressure and improved when it was removed, while other groups performed better under pressure. A visible timer lowered anxiety before the task and reduced restless behavior during it, with no significant difference in maths performance.
What it means for you: Visible time can be used as an open, calming frame. Beat the clock helps kids persist or finish better is a claim we refuse.
231Moderate
About one child in six builds a detailed imaginary world of their own.
Taylor, Mottweiler, Aguiar, Naylor & Levernier (2020), Child Development
Moderate: two small studies inside the band, with one clear difference in storytelling
Who was studied: Children ages 8 to 12, in two studies of 77 and 92 children.
What they found: About 17 percent of children had built a paracosm, a made-up world with its own places, people, and rules, revisited over months. Those children scored higher on one storytelling task. They did not differ on vocabulary, on thinking up different ideas, or on working memory.
What it means for you: World-building missions fit ages 9 to 10: maps, invented places, characters who return, secrets the child keeps. Most children will not sustain one, and that is normal.
232Moderate
Nearly a third of very young children have one extremely intense interest.
DeLoache, Simcock & Macari (2007), Developmental Psychology
Moderate for how common intense interests are in early childhood; thin for how long any one interest lasts into ages 7 to 10
Who was studied: Parents of 177 young children, mostly toddlers and preschoolers, below our 5 to 10 band. The entry is here because the interests that start this early are the ones packs at 5 to 6 borrow.
What they found: Nearly one child in three had an extremely intense interest, and another 37 percent had a moderate one. Interests began as early as ages 1 to 2 and lasted about 22 months on average. Boys most often loved vehicles, trains, machines, dinosaurs, and balls; girls most often loved dress-up and books, and many children broke the pattern in both directions.
What it means for you: A 5 to 6 pack works best when it is built on the child's already loved category, rather than a theme we invent. We ask for the loved category in our survey. We never assign a theme by gender.
233Moderate
Rough-and-tumble play peaks in middle childhood.
Pellegrini & Smith (1998), Child Development
Moderate: the peak sequence rests on replicated observation; the claimed benefits of rough-and-tumble play did not clear the review's own bar
Who was studied: A review of observational studies of physical play, from infancy through middle childhood.
What they found: Physical play peaks in sequence: rhythmic movements in infancy, exercise play in the preschool years, and rough-and-tumble play in middle childhood. Rough-and-tumble play made up roughly 10 percent of free play in the early grades, falling to about 5 percent by age 11. The review judged claims that it teaches fighting skill or reading social signals as unproven.
What it means for you: Chase, wrestling-style, and physical challenge missions are native content at ages 7 to 10, with the weight peaking at 7 to 8. Movement is fuel for the product, not a break from it.
234Studied in grown-ups
People speed up as a visible finish gets close.
Kivetz, Urminsky & Zheng (2006), Journal of Marketing Research
Moderate as adult field evidence; thin for this product, because no child sample exists
Who was studied: Adult cafe loyalty program members, plus adult laboratory studies. No children were studied, so this is borrowed, not measured, at ages 5 to 10.
What they found: Reward members bought more often as the free coffee neared, with the gap between purchases shrinking by about 20 percent near the goal. Giving people an impression of progress sped them up further, and faster finishers were more likely to stay in the program.
What it means for you: An arc pack shows its finish from the first day, names the final day, and keeps the remaining distance small and concrete. We do not cite the goal gradient as child evidence.
235Studied in grown-ups
A progress card that starts partway done gets finished more often.
Nunes & Dreze (2006), Journal of Consumer Research
Moderate as a field experiment; thin for this product, because the customers were adults
Who was studied: 300 adult car wash customers, 150 in each condition.
What they found: A card needing eight stamps, printed with ten slots and two already stamped, was completed by 34 percent of customers, against 19 percent for a blank eight-stamp card. The work left to do was identical. The authors put the effect down to perceived progress, not to reluctance to waste the endowed stamps.
What it means for you: Day one of an arc leaves the child visibly partway there: the first piece pre-made, or earned with almost no work. The endowment must be real progress the child can see, not a fake head start.
236Studied in grown-ups
On people's best days at work, small progress was usually the reason.
Amabile & Kramer (2011), Harvard Business Review
Moderate as adult evidence from one large diary corpus; thin for this product, because no child or home play sample exists
Who was studied: 238 adult knowledge workers on 26 project teams in seven companies, writing nearly 12,000 daily diary entries.
What they found: Steps forward appeared on 76 percent of best-mood days, and setbacks on 67 percent of worst-mood days. Many reported steps forward were minor, yet they often produced outsized positive reactions, and small setbacks hurt more than equal progress helped. The authors state the analyses show correlation, not causation.
What it means for you: Each arc day ends with a visible small win, and work in progress is protected from setbacks, because a damaged day-two artifact costs more motivation than a success buys. Grown-up scripts name the progress made, not praise of the child.
237Strong
Brain training improves the practiced task, and sometimes very similar tasks for a short time. It does not reliably improve general ability.
Melby-Lervåg and Hulme (2013), Developmental Psychology; Melby-Lervåg, Redick and Hulme (2016)
Strong (as a null): four meta analyses and one major review converge, with child specific confirmation, and a randomized trial inside the 5 to 10 band
Who was studied: Meta analyses and a major review spanning children and adults, with a children only analysis and a randomized trial inside the 5 to 10 band.
What they found: Near transfer effects were reliable and short term, and gains were not sustained at follow up. There was no convincing far transfer against treated controls. In children only, the far transfer average was 0.12 against a near transfer average of 0.46, and effects shrank as study design improved.
What it means for you: Memory demanding games are presented honestly, as games that use working memory while they are played. Guessing games build working memory is refused, for our games and for training programs far stronger in dose.
238Checked
The 8-second attention span is a fabrication. There is no study behind it.
Maybin (2017), BBC News, "Busting the attention span myth"
Settled negative: the figure is a fabrication with a traced provenance; journalism is the strongest evidence available about a claim that has no study
Who was studied: Not applicable. This is a claim about a statistic's provenance, not a study of children.
What they found: The figure traces to a 2015 Microsoft Canada marketing report, which took it from a website called Statistic Brain. The organizations Statistic Brain named as its sources had no record of the research, and Statistic Brain produced none. Attention researchers told the BBC that a single average attention span is a meaningless number, because attention depends on the task. The related minutes-per-year-of-age rule is held separately as folklore.
What it means for you: We refuse all attention span numbers in copy and in design math. When a parent asks how long their child can focus, we answer with the task dependence answer: it depends on the task.
No studies match. Try a different word or pick another category.
