This paper evaluates the impact of two kinds of teacher’s aides on 13-year-old students’ test scores, behavior and wellbeing. We gain leverage from combining a randomized experiment with rich survey and registry data from Denmark. The intervention reduces student-to-teacher ratios by 27-34%, but it is a much more flexible instrument than class-size reduction. We find substantial positive effects on reading scores, which tend to be greater when resources are spent on teaching assistants without teaching degrees who—at a fixed budget—can spend more time in class in comparison to co-teachers with teaching degrees. |