The protests began last month at high schools in Paris' poor northern suburbs, where anger over teacher absences and shabby facilities quickly morphed into a nationwide movement against inequality, weak public spending and falling standards.
A large police presence was visible in central Paris, especially near landmarks such as the Avenue des Champs-Elysees and the Arc de Triomphe, which were excluded from the routes of the two official demonstrations. Hundreds of other protests were planned across France, with tens of thousands set to participate. In Marseille, trash cans were set alight.
"We are fighting because the cost of living is too harsh, because the price of fuel is too high, because high school pupils are being violently attacked and hurt all over the country just for trying to protest and ask for more teachers and decent learning conditions," said a 19-year-old protester in Paris who gave her name as Lola.
Prime Minister Sebastien Lecornu said on Thursday that authorities fear unrest during the protests. The government accused the hard-left France Unbowed of inflaming the protests, an accusation it denies.
The police have drawn criticism for the response after a series of injuries among demonstrators, including one adolescent who had his hand blown off after picking up a stun grenade. Lecornu said more than 900 police had also been injured. The internal police watchdog is investigating at least two dozen cases of alleged police violence. France suspended the use of stun grenades for student demonstrations, but Interior Minister Laurent Nunez said they could be used on Saturday.
Calls on social media for members of past protest movements to join the fray appear to have worked, suggesting the protests could grow significantly. The Yellow Vest movement started in 2018 as a protest against taxes on diesel before expanding into an outpouring of anger at high living costs and income inequality. Yannick Maillou, a teacher from La Crèche in western France, joined the Yellow Vests in 2018 and remains involved in the movement.