Explore the evidence
4 of 88 decisions · clear everything
Survives the gold standardIndependent, durable, rigorousThe debunked shelfCheap winsFor parents at homeFamous numbers, deflatedWhere we admit ignoranceThe terrain
domain
Your situation · from the applicability layer — absence means “not yet assessed,” never “doesn’t apply”
who's delivering
outcome class
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: low17/1936/48
Grade retention — holding a child back versus promoting, and test-based promotion policies · retention · ages 5–18 · structure
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: low22/2338/48
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: medium18/2036/48
Test preparation — does coaching raise scores, and does a raised score mean raised ability? · assessment · ages 5–18 · structure
No study of homeschooling has a counterfactual — the famous percentile claims are selection all the way down. The honest answer: nobody knows.
insufficientconf: lowgc: high15/2336/48connected: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
Not yet assessed for this question · 15
- Acceleration and gifted programs — the label vs the content
- Does working-memory or brain training transfer to intelligence and achievement?
- Class-size reduction
- Curriculum choice as a school-level lever
- Fadeout — why early gains disappear, and what actually persists
- Ability grouping and tracking — four practices, four verdicts
- Homeschool socialisation — the most-asked question, and the least answerable one
- Does matching instruction to a child's "learning style" improve learning?
- Brain Gym, Whole Brain Teaching, and the smaller classroom brain fads
- Should Gardner's multiple intelligences be used as a basis for instruction?
- 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
- Teacher quality — selection over credentials and workshops
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