The Evidence on Teaching

Explore the evidence

7 of 88 decisions · clear everything

Survives the gold standardIndependent, durable, rigorousThe debunked shelfCheap winsFor parents at homeFamous numbers, deflatedWhere we admit ignoranceThe terrain
evidencealldrop DA–BA only
evaluatoranyno dev-ledindependent
durabilityanyfollow-up≥1yr≥2yr
what are these? →
sortconfidencerobustfragileA–Z
domain
verdict
confidence
layer
Your situation · from the applicability layer — absence means “not yet assessed,” never “doesn’t apply”
who's delivering
group / setting
cost
outcome class

Early gains fade by default — halving every 12–18 months, faster when bigger. What persists is trajectory (placement, graduation), not ability.

strong supportconf: highgc: low
10/1048/48connected:Does working-memory or brain trainDoes learning to code improve geneCan executive function be trained,Does teaching a growth mindset rai+2

Fadeout — why early gains disappear, and what actually persists · early-childhood · ages 4–18 · structure

Smaller classes buy real K-1 gains that fade on tests yet persist in attainment — at roughly triple tutoring's cost, and diluted to nothing when scaled fast.

mixedconf: highgc: low
7/748/48connected:TutoringDoes educational technology raise Teacher quality

Class-size reduction · class-size · ages 4–18 · structure

At scale, pre-K doesn't durably raise test scores — Tennessee went negative — yet Boston shows real attainment gains beside a test-score zero. It buys trajectory, not ability.

mixedconf: highgc: low
17/1748/48connected:FadeoutPerry Preschool and Abecedarian

Preschool at scale — Head Start, state pre-K, and what universal provision delivers · early-childhood · ages 4–5 · structure

Starting school older mostly manufactures an age-at-test artifact: the IQ effect collapses to ~−0.07 once identified. Real residues: less hyperactivity, unchanged attainment.

mixedconf: highgc: low
6/636/48connected:Algebra timing

School starting age, relative age, and academic redshirting · early-childhood · ages 4–7 · structure

Most measured 'home environment' effects are parents' genes: three-quarters of parent-child transmission isn't rearing, and a whole better childhood buys ~4 IQ points.

mixedconf: highgc: low
12/1236/48connected:The parent as instructor

The early home environment — what parents can and cannot causally move · early-childhood · ages 4–10 · input

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: low
19/1936/48

Grade retention — holding a child back versus promoting, and test-based promotion policies · retention · ages 5–18 · structure

Perry and Abecedarian: n=123 and n=111, IQ gains gone by adolescence, attainment effects real but multiplicity-fragile. Too thin to carry the policy built on them.

mixedconf: mediumgc: low
8/836/48connected:Preschool at scale

Perry Preschool and Abecedarian — what the famous studies actually establish · early-childhood · ages 4–5 · structure

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