Chilean students have been boycotting classes to press their demands for education reform.
On Tuesday they took their demands onto the streets in the biggest protest so far.
The rallies began peacefully but trouble erupted as students threw stones.
Riot police moved in to confront protesters in the capital, Santiago.
They used tear gas and water cannon to disperse one of the biggest student demonstrations in Chile for decades.
More than 700 people were arrested across Chile, most of them in the capital.
Several people were injured including bystanders caught up in the demonstrations.
"We are the future" reads this banner at a school in Santiago.
The government is talking to student leaders but for now school is out for many pupils.