Online learning during school closure due to COVID-19.

This paper estimates the effects of school closure on students' study time and the number of messages sent from teachers to students using an online learning service. We find that both study time and message numbers increased significantly from the beginning of the school closure but they returned to pre-COVID-19 levels when the state of emergency ended in late May 2020. In addition, we find that students with prior access to the online learning service at home and students at higher-quality schools increased their study time more than other students. However, we find no gender differences in these outcomes.