Instructional time is a fundamental educational input, yet we have little causal evidence about the effect of longer school days on student achievement. This paper uses a sharp regression discontinuity design to estimate the effects of lengthening the school day for low-performing schools in Florida by exploiting an administrative cutoff for…

Expanded learning time (ELT) refers to a longer school day, week, or year. ELT schools are becoming common in the United States and aim to provide all students with additional opportunities for learning, recreation, and enrichment. ELT schools differ from afterschool programs that take place immediately following the regular school day and serve a…