Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
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.