Test-score gains from early-childhood programmes largely disappear within a few years, even where some later-life benefits persist.
The randomised Head Start Impact Study found in 2010 that children's early cognitive advantages had largely gone by the end of first grade. Deming's 2009 comparison of siblings nonetheless found that Head Start participants did better as young adults, which is the puzzle: effects that vanish from tests and reappear in outcomes. Tennessee's statewide pre-kindergarten trial went the other way, with participants scoring below the control group by sixth grade.
In practice
- A city funds a pre-school programme on its early test gains and has to decide what to do when the gains are gone by fifth grade.
- A child drilled in reading before school starts reads early, and by eight the classmates who started later have caught up.
- Possible explanations
- Candidate explanations are that the early gains were in skills schooling later teaches everyone, that control-group children catch up, that the tests measure what fades rather than what lasts, and that benefits move from test scores into behaviour and later outcomes.
- In its favour
- The pattern is documented in randomised evaluations, including the Head Start Impact Study, and the later-life gains found in sibling comparisons are real.
- Against it
- Which explanation holds is unresolved, and Tennessee's statewide pre-kindergarten trial found participants below the control group by sixth grade, which none of the reassuring accounts predicts.
- Standing
- Whether fade-out means the gains were never real, that later schooling lets the others catch up, or that benefits move from test scores into behaviour and later outcomes is the live question. Compare the Heckman curve.
- Subject
- Learning & Education
- Essay
- What works in learning, and what schools can and cannot change