The COVID-19 pandemic-associated learning losses were unequal across school subjects and sociodemographic groups. This study posits that these losses are also heterogeneous based on pre-pandemic school effectiveness, that is, the value schools added above the expected students' learning based on their socioeconomic background. Using national-scale…

This study estimates the effect of between-class ability grouping on Chilean secondary students' academic achievement. We rely on a structural feature of the school system: A considerable number of students who complete primary school must change schools to start their secondary education. Cardinality matching was performed to account for…