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
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Your situation · from the applicability layer — absence means “not yet assessed,” never “doesn’t apply”
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High-dosage tutoring is education's most reliable lever: ~0.29 SD in trials, ~0.2 well-scaled — not Bloom's 2σ. Groups of 3–4 work; 1:1 is unnecessary.

strong supportconf: highgc: low
18/1830/48connected:Class-size reductionDoes educational technology raise The parent as instructorSchool spending, charters, and wha

Tutoring — the honest effect, the Bloom 2-sigma myth, and what survives scale · tutoring · ages 5–18 · method

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: low
8/824/48

Does dual-language immersion work, and is the gain in the second language or in English? · foreign-language · ages 4–18

A missed day costs little (~0.005 SD); interventions reliably buy days back cheaply, but nobody has shown the recovered days move achievement.

mixedconf: mediumgc: medium
14/1439/48

Chronic absenteeism — does raising attendance raise achievement? · time · ages 4–18 · input

Explicit form-focused teaching beats pure exposure, so the archive's negative verdict on L1 grammar does NOT transfer — but the effects are measured on the taught forms, immediately, mostly on adults.

mixedconf: mediumgc: low
11/1118/48connected:Does teaching grammar improve chil

Comprehensible input or explicit grammar teaching — which builds a second language? · foreign-language · ages 4–18

Sort by what the software replaces: adaptive drill inside the school day buys +0.05-0.20 SD; a device, a connection or the teacher buys zero to negative; LLM tutors have no usable evidence at all.

mixedconf: mediumgc: low
53/5339/48connected:Placement and mastery diagnosisMastery learning (teach → test → rTutoringClass-size reduction

Does educational technology raise learning — CAI, adaptive software, devices, screens, and AI tutors? · edtech · ages 5–18 · structure

Attainment falls steadily with age of first exposure, but the sharp critical period is contested and an earlier classroom start buys nothing durable: start young for immersion, not for two lessons a week.

mixedconf: mediumgc: medium
14/1424/48

Is there a critical period for learning a second language, and when should a child start? · foreign-language · ages 4–18

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: low
23/2338/48

Length of the school day and year, time-on-task, extended time, and summer · time · ages 4–18 · structure

The URL is the state — any view you build here is a permalink you can hand to someone mid-argument.