„In all education systems, students differ from each other in their backgrounds, experiences, abilities and needs. Many countries try to cater for these differences by introducing differentiation into their education system. Differentiation is provided by grouping students based on their ability, interest, or other characteristics. Students may be grouped within classes, in different classes, schools or school programmes/pathways.“
EU-Kommission (Hrsg.), Equity in school education in Europe (2020), S. 75.