The field is generally aware of the summer learning loss (SLL) phenomenon. However key characteristics of SLL are not broadly established. What proportion of students’ school-year gains are lost in the subsequent summer? Is the magnitude of SLL generally similar across students or across grades? We describe the role summers play in the end-of-schooling achievement disparities using a unique dataset that spans eight grades, 200 million test scores, 18 million students, 50 states, and school-years 2008-2016. On average, 19% of students’ pathways from their 1st to 8th grade test-score occur during summers. We show that—even if all inequality in school-year learning rates could be eliminated, students would still end school with very different achievement due to SLL alone.
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.