The distributional impacts of a universal school reform on mathematical achievements: A natural experiment from Canada

We investigate the impact of an ambitious provincial school reform in Canada on students' mathematical achievements. It is the first paper to exploit a universal school reform of this magnitude to identify the causal effect of a widely supported teaching approach on students' math scores. Our data set allows us to differentiate impacts according to the number of years of treatment and the timing of treatment. Using the changes-in-changes model, we find that the reform had negative effects on students' scores at all points on the skills distribution and that the effects were larger the longer the exposure to the reform.