Explore the evidence
18 of 88 decisions · clear everything
Survives the gold standardIndependent, durable, rigorousThe debunked shelfCheap winsFor parents at homeFamous numbers, deflatedWhere we admit ignoranceThe terrain
domain
- math6
- reading6
- early childhood5
- debunked3
- health3
- practice3
- science3
- writing3
- arts2
- assessment2
- grouping2
- history civics2
- homeschool2
- instruction style2
- motor skills2
- time2
- class size1
- computer science1
- curriculum1
- deliberate practice1
- feedback1
- foreign language1
- mastery1
- physical development1
- practical1
- retention1
- school structure1
- sport1
- talent1
- teachers1
- transfer1
- tutoring1
Your situation · from the applicability layer — absence means “not yet assessed,” never “doesn’t apply”
Immersion costs nothing in English and buys a little — a lottery puts English reading 0.13-0.22 SD ahead by grades 5 and 8 — but no lottery has ever measured how much of the second language students actually learn.
moderate supportconf: mediumgc: low8/824/48
Does dual-language immersion work, and is the gain in the second language or in English? · foreign-language · ages 4–18
Teaching handwriting works and transfers: freeing the hand frees composition, with gains still present at six months — even taught in groups of three.
moderate supportconf: mediumgc: medium8/818/48connected:Does teaching grammar improve chilDoes teaching movement transfer toDoes sentence combining improve wrDoes teaching spelling work, and w+1
Does handwriting and transcription instruction matter, and should young children type instead? · writing · ages 5–12
Teaching coding teaches coding: the one clean school RCT gives g=0.47-0.68. Which approach you pick barely matters, and almost every effect size rests on an instrument the developers built.
moderate supportconf: mediumgc: lowDoes teaching programming actually teach programming — and does the method matter? · computer-science · ages 5–18
Formal spelling instruction works (ES 0.54) and more formal beats less formal — explicit wins again, and it transfers beyond spelling itself.
moderate supportconf: mediumgc: low7/79/48connected:Does teaching grammar improve chilDoes sentence combining improve wrSystematic/explicit phonics vs whoExplicit instruction vs discovery/+3
Does teaching spelling work, and what does it transfer to? · writing · ages 5–18
Diagnose what a child already knows: teachers cut 40–50% of curriculum for high-ability children and achievement ROSE. The payoff is skipping, not monitoring.
moderate supportconf: mediumgc: medium16/1625/48connected:Does educational technology raise Feedback and formative assessmentMastery learning (teach → test → r
Placement and mastery diagnosis — deciding what to teach next from evidence of current skill · assessment · ages 5–18 · structure
Content-rich history teaching raises history knowledge (g 0.19-0.46) but not standardized reading in under three years; generic 'historical thinking' has no adequately controlled positive result.
moderate supportconf: mediumgc: lowShould history be built on content knowledge or on generic historical-thinking skills? · history-civics · ages 5–18
Life-skills courses reliably teach the content and rarely change the conduct; behaviour moves only where instruction sits close in time to the decision, and driver education is worse than nothing.
mixedconf: mediumgc: low11/1148/48
Do life-skills courses — money, cooking, driving, health — change what students actually do? · practical · ages 6–18
Civics teaching buys civic knowledge (d = 0.49) that fades to the control mean in two years and moves neither attitudes nor validated turnout; what moves voting is school quality and noncognitive skill.
mixedconf: mediumgc: low19/1936/48
Does civic education produce civic knowledge, and does civic knowledge produce civic behaviour? · history-civics · ages 5–18
The received wisdom that retention is harmful was two measurement errors, not a finding. Fix them and the achievement effect is zero — but the grade at which you hold a child back decides everything.
mixedconf: mediumgc: low19/1936/48
Grade retention — holding a child back versus promoting, and test-based promotion policies · retention · ages 5–18 · structure
Guided inquiry is positive in 16 of 16 PISA regions and unguided inquiry negative in 18 of 20 — but the programmes built on that finding go to zero at scale: +0.22, then +0.01, then +0.02 on the same test.
mixedconf: mediumgc: low19/1927/48connected:Science content sequencingExplicit instruction vs discovery/Laboratory and practical work in sTeaching students to think scienti
Inquiry-based science teaching vs explicit and textbook science teaching · science · ages 8–18
Taking time away hurts measurably; adding it back buys almost nothing. The return per hour is ~0.02-0.03 SD, concave, and near zero in disorderly classrooms.
mixedconf: mediumgc: low23/2338/48
Length of the school day and year, time-on-task, extended time, and summer · time · ages 4–18 · structure
Coaching buys ~0.25 SD of score and has for 42 years — a fraction of what's advertised — and none of it is ability. The score moves; the construct doesn't.
mixedconf: mediumgc: medium20/2036/48
Test preparation — does coaching raise scores, and does a raised score mean raised ability? · assessment · ages 5–18 · structure
What parents are asked to DO is the whole effect: tutoring a skill d≈1.15, listening to reading 0.51, reading aloud ~0.18 — same parent, same child. All deflate under better designs.
mixedconf: mediumgc: medium33/3336/48connected:Homeschool socialisationDoes homeschooling raise achievemeThe early home environmentTutoring
The parent as instructor — what survives when the person teaching is the person who raised the child · homeschool · ages 4–18 · method
Narrow reasoning routines are teachable and stay taught for seven months. The far-transfer claim failed its one randomised test: science −0.01, English −0.15, maths −0.11.
no effectconf: mediumgc: lowTeaching students to think scientifically — does it transfer? · science · ages 7–18
No trial has ever varied the sequence of science content and measured the result. The one quasi-experimental test of course order found nothing, and depth-over-breadth is a retrospective survey worth 0.08-0.13 SD.
insufficientconf: mediumgc: medium15/1515/48connected:Background knowledge and vocabularInterleaving (mixing problem typesExplicit instruction vs discovery/Inquiry-based science teaching vs +1
Science content sequencing — coherence, prerequisites, and course order · science · ages 5–18
Teaching grammar does not improve writing at any age tested — and it displaces the things that do.
negativeconf: mediumgc: low12/1227/48connected:Comprehensible input or explicit gDoes sentence combining improve wrDoes teaching spelling work, and wDoes handwriting and transcription+4
Does teaching grammar improve children's writing? · writing · ages 5–18
No study of homeschooling has a counterfactual — the famous percentile claims are selection all the way down. The honest answer: nobody knows.
insufficientconf: lowgc: high23/2336/48connected:Homeschool socialisationThe parent as instructorSystematic/explicit phonics vs whoMath-fact fluency and timed practi
Does homeschooling raise achievement and attainment, or does it select the children who would have done well anyway? · homeschool · ages 5–18 · structure
Nobody has tested it. There is no controlled trial in which art instruction is the input and independently measured art skill is the outcome — the field's core claim is the one it never studied.
insufficientconf: lowgc: medium6/618/48connected:Does arts education raise academicBrain Gym, Whole Brain Teaching, aAre museum and theatre trips worth
Does teaching visual art produce artistic skill? · arts · ages 4–18
Not yet assessed for this question · 46
- Acceleration and gifted programs — the label vs the content
- Algebra timing — acceleration mandates, delay mandates, and readiness-based placement
- Does arts education raise academic achievement?
- Chronic absenteeism — does raising attendance raise achievement?
- Background knowledge and vocabulary as drivers of reading comprehension
- Does working-memory or brain training transfer to intelligence and achievement?
- Class-size reduction
- Curriculum choice as a school-level lever
- Deliberate practice and the 10,000-hour rule
- Physical activity as an input — dose, fitness, and school outcomes
- Explicit instruction vs discovery/inquiry — how much guidance?
- Explicit vs reform/constructivist math instruction
- Fadeout — why early gains disappear, and what actually persists
- Feedback and formative assessment
- Ability grouping and tracking — four practices, four verdicts
- The early home environment — what parents can and cannot causally move
- Interleaving (mixing problem types vs blocking)
- Does matching instruction to a child's "learning style" improve learning?
- Manipulatives and concrete-representational-abstract (CRA) sequences
- Mastery learning (teach → test → reteach to criterion → advance)
- Math curriculum choice — how much does the textbook matter?
- Math-fact fluency and timed practice (and the anti-timed-test claims)
- Brain Gym, Whole Brain Teaching, and the smaller classroom brain fads
- Does teaching movement transfer to cognition, achievement, or lifelong activity?
- Feedback frequency and mental practice in motor learning
- Practice scheduling for motor skills — varied vs blocked, spaced vs massed
- Should Gardner's multiple intelligences be used as a basis for instruction?
- Breakfast, school meals, and micronutrients — what feeding children actually buys
- Phonemic awareness training (and whether it needs letters)
- Systematic/explicit phonics vs whole language and balanced literacy
- Preschool at scale — Head Start, state pre-K, and what universal provision delivers
- Perry Preschool and Abecedarian — what the famous studies actually establish
- Reading-comprehension strategy instruction (reciprocal teaching, summarizing, questioning)
- Reading fluency — guided repeated oral reading, and whether repetition matters
- Reading Recovery and Tier-2 1:1 early-literacy tutoring
- Retrieval practice (the testing effect)
- School spending, charters, and what school-level choices actually move outcomes
- School starting age, relative age, and academic redshirting
- Spaced (distributed) practice
- Talent and trainability — what is heritable, and what that does not license
- Teacher quality — selection over credentials and workshops
- Tutoring — the honest effect, the Bloom 2-sigma myth, and what survives scale
- Vision — outdoor time against myopia, and screening and correction for achievement
- Word problems, schema instruction, and the conceptual-vs-procedural question
- Worked examples (studying solutions vs solving problems)
- Early sport specialization, talent selection, and the relative age effect
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