Teachers are angry at reform plans
French teachers have gone on strike for the fourth time since the start of the academic year.
They are protesting against plans to reform pensions and decentralise parts of the education system.
Early information from trades unions suggested that around 50% of French teachers had heeded the strike call.
However, the French Education Ministry said the figure was as low as 22% in colleges. It said the highest support - in secondary schools - was only 33%.
A wider day of strikes involving other public sector workers is planned for 13 May.
The only way I know of avoiding strikes and buying public peace is to reform nothing at all. Don't count on me to do that
French Education Minister
In a separate dispute, some staff at the Bank of France also stopped work, in protest at reform plans and proposed job cuts.
Education Minister Luc Ferry has insisted that he will not be deterred from pushing ahead with his reforms.
"The only way I know of avoiding strikes and buying public peace is to reform nothing at all. Don't count on me to do that," Mr Ferry told France Inter radio.
Under the changes, some functions currently handled centrally by the French state would be devolved to regional authorities.
For example, around 100,000 maintenance, technical and medical posts would be employed regionally.
Teachers fear the result will be fewer jobs and the eventual break-up of France's prized national education system.
On pensions, the government wants to make workers pay into the scheme for longer, in an attempt to defuse the "demographic timebomb" created by an ageing population.
Under the plans, workers would have to contribute for 40 years to qualify for a full pension - an extra two-and-a-half years.
The last attempt to introduce similar reforms was brought down by strikes in 1995, and the conservative government itself fell two years later.