„The potential of small classes for creating a supportive learning environment is visible in PISA 2015 data: on average across OECD countries, and according to students’ reports, science teachers with smaller class sizes are more likely to adapt their lessons to the needs and knowledge of their students than science teachers in schools with larger class sizes. In addition, in almost every OECD country, students whose science teachers adapt more frequently their teaching outperform academically students whose teachers adapt their teaching less frequently, even after accounting for students’ and schools’ socio-economic profile.“
OECD (Hrsg.), Learning in rural schools (2019), S. 27.