„On average, 63 percent were in schools where most students (more than 90 %) spoke the language of the TIMSS assessment as their first language, and another 18 percent were in schools where more than half of students (51–90 %) spoke the language of the assessment as their first language.“
IEA (Hrsg.), TIMSS 2019. International Results in Mathematics and Science (2020), S. 316.
In Österreich besuchen nur 21 Prozent der 10-Jährigen Schulen, in denen mehr als 90 Prozent der SchülerInnen in ihrer Erstsprache unterrichtet werden. (Quelle: ibidem, S. 317.)