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
domain
layer
Your situation · from the applicability layer — absence means “not yet assessed,” never “doesn’t apply”
who's delivering
group / setting
cost
outcome class
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: medium14/1424/48
Is there a critical period for learning a second language, and when should a child start? · foreign-language · ages 4–18
Not yet assessed for this question · 6
- Fadeout — why early gains disappear, and what actually persists
- The early home environment — what parents can and cannot causally move
- Does teaching movement transfer to cognition, achievement, or lifelong activity?
- Preschool at scale — Head Start, state pre-K, and what universal provision delivers
- Perry Preschool and Abecedarian — what the famous studies actually establish
- School starting age, relative age, and academic redshirting
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