Explore the evidence
1 of 88 decisions · clear everything
Survives the gold standardIndependent, durable, rigorousThe debunked shelfCheap winsFor parents at homeFamous numbers, deflatedWhere we admit ignoranceThe terrain
Your situation · from the applicability layer — absence means “not yet assessed,” never “doesn’t apply”
who's delivering
group / setting
cost
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: low18/1836/48
Do later school start times increase adolescent sleep, and does that raise achievement? · health · ages 11–18 · input
Not yet assessed for this question · 16
- Acceleration and gifted programs — the label vs the content
- Chronic absenteeism — does raising attendance raise achievement?
- Class-size reduction
- Curriculum choice as a school-level lever
- Physical activity as an input — dose, fitness, and school outcomes
- Fadeout — why early gains disappear, and what actually persists
- Ability grouping and tracking — four practices, four verdicts
- The early home environment — what parents can and cannot causally move
- Breakfast, school meals, and micronutrients — what feeding children actually buys
- Preschool at scale — Head Start, state pre-K, and what universal provision delivers
- Perry Preschool and Abecedarian — what the famous studies actually establish
- School spending, charters, and what school-level choices actually move outcomes
- School starting age, relative age, and academic redshirting
- Talent and trainability — what is heritable, and what that does not license
- Teacher quality — selection over credentials and workshops
- Vision — outdoor time against myopia, and screening and correction for achievement
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