Summer learning loss (SLL) is a familiar and much-studied phenomenon, yet new concerns that measurement artifacts distorted canonical SLL findings create a need to revisit basic research on SLL. Though race/ethnicity and SES only account for about 4% of the variance in SLL, nearly all prior work focuses on these factors. We zoom out to the full spread of differential SLL and its contribution to students’ positions in the eighth grade achievement distribution. Using a large, longitudinal Northwest Evaluation Association dataset, we document dramatic variability in SLL. While some students actually maintain their school-year learning rate, others lose nearly all their school-year progress. Moreover, decrements are not randomly distributed—52% of students lose ground in all 5 consecutive years (ELA).
This study is a randomized control trial of full- versus half-day pre-kindergarten in a school district near Denver, Colorado. Four-year-old children were randomly assigned an offer of half-day (four days/week) or full-day (five days/week) pre-k that increased class time by over 600 hours. The offer of full-day pre-k produced substantial, positive effects on children’s receptive vocabulary skills (0.267 standard deviations) by the end of pre-k. Among children enrolled in district schools, full-day participants also outperformed their peers on teacher-reported measures of cognition, literacy, math, and physical development. At kindergarten entry, children offered pre-k still outperformed peers on a widely-used measure of basic literacy. The study provides the first rigorous evidence on the impact of full-day preschool on children’s school readiness skills.