Does student-teacher match quality exist? Prior work has documented large disparities in teachers' impacts across student types but has not distinguished between sorting and causal effects as the drivers of these disparities. I propose a disparate value-added model and derive a novel measure of teacher quality--revealed comparative advantage--that…

Using administrative data from D.C. Public Schools, I use exogenous variation in the presence and intensity of teacher monitoring to show it significantly improves student test scores and reduces suspensions. Uniquely, my setting allows me to separately identify the effect of pre-evaluation monitoring from post-evaluation feedback. Monitoring's…