Teacher Effectiveness and Classroom Composition: Understanding Match Effects in the Classroom

This paper provides evidence of match effects in the teacher labour market by considering how teacher effectiveness varies by classroom composition. We combine random assignment of teachers with rich measures of teaching practices based on a popular teacher-evaluation protocol to overcome endogeneity challenges. We find significant complementarities between teaching practice and classroom composition for maths achievement. We use these estimates to simulate the effects of reallocating classrooms among teachers within schools and find substantial differences between counterfactual and actual teacher effectiveness rankings. These findings support the importance of classroom composition for key teacher-related policies, including teacher allocations, accountability, and training.