Single-track year-round education for improving academic achievement in U.S. K-12 schools: Results of a meta-analysis

Research shows that over summer break, students forget approximately 1 month of learning in math and reading; furthermore, some studies find that low-income students lose ground relative to peers. Year-round education (YRE) redistributes schooldays to shorten summer. Prior analyses pooled single-track YRE (academic intervention in which all students attend school on a common calendar) and multitrack YRE (fiscal intervention countering overcrowding, in which groups of students attend school on staggered schedules).

Systematic search of 22 online databases in summer 2017 yielded 494 de-duplicated results; 81 warranted full-text examination. After applying selection criteria, nine studies met criteria but did not report data that allowed effect size calculation. Thirty studies constituted our analytic sample.

Studies needed to be of K-12 single-track YRE (not multitrack, not a mix of single- and multitrack, and not a study that did not specify track), with no accompanying extended instructional time. Studies needed to be from 2001 to 2016, include outcome data, and include a comparison group.

We extracted 55 math g, 58 reading g, 29 math odds ratio, and 27 reading odds ratio effect sizes.

Students at single-track YRE schools show modestly higher achievement in both math and reading-by a magnitude similar to estimates of summer learning loss-but comparable proficiency. Unexpectedly, the effect was no greater for historically disadvantaged students. Math effects may be larger in middle than elementary school, but the reason is unclear. Importantly, studies of schools that shortened summer to the fewest weeks showed the largest effects in both subjects.