„During the summer, a little more than half of students exhibit summer learning losses, while the other half exhibits summer learning gains. It is clear that the summer period is a particularly variable time for students. We find that some students can in fact maintain average school-year learning rates during the summer in the absence of formal schooling. Other students, however, will lose nearly as much as what is typically gained in the preceding school year. This remarkable variability in summer learning appears to be an important contributor to widening achievement disparities during the school-age years.“
Univ.-Prof. Dr. Allison Atteberry u. a., School’s Out: The Role of Summers in Understanding Achievement Disparities (2020), S. 23.