The Effectiveness of Single-Sex Schools through Out-of-School Activities: Evidence from South Korea

Students’ out-of-school activities and time use can play a crucial role in facilitating the effect of schools on students’ achievement. Using data from Seoul, South Korea, where students are randomly assigned into schools, we show that when single-sex schools improve students’ test performance, their effect is positive on students’ time spent on study-related out-of-school activities. Our results indicate that out-of-school activities explain roughly 21%–30% of the effect of single-sex schooling on test performance.