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…

The Massachusetts Expanded Learning Time (ELT) initiative was established in 2005 with planning grants that allowed a limited number of schools to explore a redesign of their respective schedules and add time to their day or year. Participating schools are required to expand learning time by at least 300 hours per academic year to improve student…

The connection between length of school day and time allocated to 10 school subjects and scores for grade 6 in reading, writing, and mathematics was studied for 1,030 schools in the 1982 California Assessment Program. More time for science and mathematics and a longer school day correlated with higher test scores in all subjects. (SLD)