The protests were directed against proposed reforms, but in many schools - particularly in Rome, where more than 60 were occupied - much of the damage was caused by outsiders.
In one school, only 35 of the 90 people police detained were pupils. The headteacher said that the protest had been hijacked by drug-dealers.
The problem of who has to meet the cost of the damage remains unresolved. In a Student's Charter presented in December by the education minister, pupils are denied the right to strike, and are specifically required to pay for any damage they inflict on school property.
But in March last year a court in Rome ruled in favour of pupils who staged a sit-in which halted lessons for two weeks. Pupils caused an estimated Pounds 30,000 worth of damage, but the judge said that they had merely been "exercising their right to protest".