Hypothesis
Children lose substantial reading and math skills over the summer, and achievement gaps grow faster in summer than during the school year, consistently across recent large datasets.
What failed
Comparing three recent U.S. elementary-school datasets from the 2010s (ECLS-K:2011, NWEA and Renaissance), most patterns did not generalize beyond a single test: summer losses, gap growth by income, ethnicity and gender, and growth in score variance each appeared on some tests and not others, and where gaps grew they did not consistently grow faster in summer.
Broken assumption
Summer learning loss and faster summer gap growth are robust patterns that hold across achievement tests.
Why
The paper reports that the patterns depend on which test is used; it does not identify a single cause and recommends showing that a summer-learning pattern replicates before drawing broad conclusions.
From the published paper: Workman et al. Sociological Science, 2023. ↗CC BY