Explore the evidence
12 of 88 decisions · clear everything
- math6
- reading6
- writing6
- early childhood5
- science5
- arts4
- character4
- health4
- assessment3
- debunked3
- foreign language3
- history civics3
- homeschool3
- practice3
- grouping2
- instruction style2
- motor skills2
- music2
- practical2
- time2
- transfer2
- behavior1
- class size1
- computer science1
- curriculum1
- deliberate practice1
- edtech1
- feedback1
- homework1
- mastery1
- physical development1
- retention1
- school structure1
- sport1
- talent1
- teachers1
- tutoring1
Systematic phonics beats whole language for word reading — largest in K-1 and for at-risk readers; near-null for comprehension and past grade 3.
strong supportconf: highgc: lowSystematic/explicit phonics vs whole language and balanced literacy · reading · ages 4–9
Teaching movement teaches movement: the skills improve, but transfer to cognition, achievement, or lifelong activity is near zero in the best trials.
no effectconf: highgc: mediumDoes teaching movement transfer to cognition, achievement, or lifelong activity? · physical-development · ages 4–18
Later bells buy adolescents 40+ measured minutes of sleep — the best-identified positive effect in the archive; the achievement payoff is real but far smaller.
strong supportconf: mediumgc: lowDo later school start times increase adolescent sleep, and does that raise achievement? · health · ages 11–18 · input
Comprehension is knowledge — but vocabulary teaching moves standardized comprehension only d≈0.10. The big content-knowledge bet (Core Knowledge lottery, 0.24) is real and unreplicated.
moderate supportconf: mediumgc: lowBackground knowledge and vocabulary as drivers of reading comprehension · reading · ages 5–14
Phonemic awareness transfers to reading only with letters attached: speech-only training peaks near 10 hours and moves reading d=0.19; with print, 0.66.
moderate supportconf: mediumgc: lowPhonemic awareness training (and whether it needs letters) · reading · ages 4–7
Guided oral reading works, but the ingredient is volume, not repetition: at equal exposure, re-reading has no edge over wide reading.
moderate supportconf: mediumgc: lowReading fluency — guided repeated oral reading, and whether repetition matters · reading · ages 6–12
Outdoor time prevents myopia from starting (not progressing); screening plus free glasses raises test scores in children who need them. Two claims, both real.
moderate supportconf: mediumgc: lowVision — outdoor time against myopia, and screening and correction for achievement · health · ages 4–18 · input
Correcting a real deficiency moves cognition (iron in anaemic children: 0.79 SD); supplementing already-fed children moves nothing (35 RCTs, 19,343 children).
mixedconf: mediumgc: lowBreakfast, school meals, and micronutrients — what feeding children actually buys · health · ages 4–18 · input
Early specialization predicts junior success; later starts plus other sports predict adult world-class. Selecting on junior results selects the wrong athletes.
mixedconf: mediumgc: mediumEarly sport specialization, talent selection, and the relative age effect · sport · ages 6–18
Reading Recovery buys large short-term gains at high cost; the only US long-term estimate is negative. Early 1:1 tutoring works — this model's durability is unproven.
mixedconf: mediumgc: lowReading Recovery and Tier-2 1:1 early-literacy tutoring · reading · ages 5–8
Strategy instruction is a one-time boost, not a trainable skill: six sessions buy what fifty do, and modern at-scale trials are ~null.
mixedconf: mediumgc: lowReading-comprehension strategy instruction (reciprocal teaching, summarizing, questioning) · reading · ages 8–14
School exercise programs don't raise achievement: four of the five largest RCTs are null, and more dose doesn't rescue it. Exercise for health, not for grades.
no effectconf: mediumgc: lowPhysical activity as an input — dose, fitness, and school outcomes · health · ages 4–18 · input
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