Multigrading and child achievement

We study how grouping students of dierent grades into a single class (multigrading) aects children's cognitive achievement. To do so, we build instruments to identify the causal eect of multigrading by exploiting an Italian law that controls class size and grade composition. We focus on seven- and ten-year-old second and fth graders, respectively. Results suggest that attendance in multigrade versus single-grade classes increases students' performance on standardized tests by 19 percent of a standard deviation (24 percent, gross of the class size eect) for second graders, while it has zero eect for fth graders. The positive impact of multigrading only appears for children sharing their class with peers from higher grades and it is relatively stronger for students from disadvantaged backgrounds.