DS - secondary in Berlin, inner city, ca. 750 pupils, little outside space - restarted on 10th August - masks in corridors etc are mandatory, in class highly recomended. There's a one way system, sanitizing stations + basins in every classroom, an airing schedule (large windows everywhere), SD in classes - the vulnerable can stay home with online lessons with a medical certificate.
Outbreaks in schools are minor and usually connected with people returning from holiday or visiting family.