At a time when reformers are pushing for more classroom time while districts are reducing the number of school days, the question of whether more instructional time makes a difference for student outcomes couldn’t be more relevant.

A new study from Northwestern University’s David Figlio and his co-authors at the American Institutes for Research presents new evidence that increased instruction time improves reading skills. The study assesses the impacts of Florida’s “Extended School Day” (ESD) program, which requires (and funds) the state’s lowest-performing elementary schools to provide an additional hour of instruction each day. This additional instruction is targeted at improving student literacy, and the program requires schools employ teachers rated as “effective,” teach phonics and reading comprehension, adapt instruction to student ability, and use texts from social studies, science, and math classes. The intervention is not cheap, running around $800 per student, and previous evaluations of the program’s implementation and impact have been mixed, calling into question whether the program is worth the cost.

Since Florida assigns the 100 worst-performing schools to the program based on an arbitrary cutoff on the pre-program reading assessments, the new study exploits this method of program assignment to implement a regression discontinuity research design, a method which essentially compares schools just a little bit below and just a little bit above that cutoff. (The program has been scaled up to the 300 worst-performing schools in more recent years.) The idea is that if schools slightly below the cutoff receive the program and then outperform the schools that are slightly above the cutoff, this is strong evidence that the program is effective.

In fact, this is exactly what the researchers find: Students in the schools that implemented the extended school day outperformed similar schools that didn’t by the equivalent of about one month of learning (0.05 standard deviations) on the end-of-year state literacy assessment. Still, the positive impacts aren’t equal for all types of students. Most troublingly, students who scored in the bottom category of the five-level pre-program literacy test saw the least growth, and the positive effects for these students weren’t even statistically significant. In contrast, it was students in the next two categories—the “2s” and “3s” on a scale of one to five—who experienced the most growth as a result of the program. These students saw even more than a month of additional learning per year from having the extended school day. Students who were already strong readers before the program started at their school—the “4s” and “5s”—also saw statistically significant increases in literacy as a result of the longer school day.

Although the schools in the study are overwhelmingly high-poverty, students from poorer families (as measured by free or reduced-price lunch eligibility) experienced double the growth (0.60 standard deviations) that the few students who didn’t qualify for free or reduced-price lunch experienced (0.30 standard deviations).

The study is not able to address the broader question of the efficacy of extending the school day for schools in general, since the methods they use yield clear effects only for schools near the reading performance cutoff, and these are only the most troubled schools. If students from high-poverty schools tend to have less educationally enriching experiences when they’re out of school than other students, extending the school day may help these students the most, although this study found some positive results for students who were from less impoverished families, as well. Overall, while it is impossible to say whether the extended school day is worth the cost without evaluating alternative policies as well, this study suggests that a longer school day can indeed lead to students learning more.

SOURCE: David Figlio, Kristian Holden, and Umut Ozek, “Do Students Benefit from Longer School Days? Regression Discontinuity Evidence from Florida's Additional Hour of Literacy Instruction?” CALDER (August 2018).

Adam Tyner is associate director of research at the Thomas B. Fordham Institute, where he helps develop and manage Fordham’s research projects. Prior to joining Fordham, he served as senior education analyst at Hanover Research, where he executed data analysis projects and worked with school districts and other education stakeholders to design custom studies. Adam has also spent several years leading classrooms, teaching…

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