„Small classes have a positive effect on student outcomes. Students assigned to small classes perform five to seven percentile points (0.20-0.28 SD units) higher than students assigned to regular classes, which had on average about seven more students than small classes. Students assigned to regular classes with a teaching assistant do not perform significantly differently than students assigned to regular classes.“
Univ.-Prof. Dr. Edwin Leuven u. a., „Class size and student outcomes in Europe“ (2018), S. 10