Pupils say their schools need more resources and classes are too big
Thousands of school pupils have staged demonstrations in cities across Germany, demanding smaller class sizes, more teachers and less exam pressure.
The current three-tier school system was condemned by some protesters. It streams pupils at age 10.
Some teachers said they sympathised with the pupils and would not hold the "strike" against them. But others said the "strike" was equivalent to truancy.
About 6,000 pupils protested in Hamburg and more than 5,000 in Berlin.
The BBC's Steve Rosenberg in Berlin says that under the current controversial system, those who fail to get into grammar schools - called Gymnasien - struggle to make it to university.
The German news website Spiegel says that in Berlin, some pupils invaded Humboldt University and managed to throw toilet rolls out of the windows.