French schoolchildren are to be given lessons in national symbols including the tricolour and the Marseillaise in an attempt to combat the spread of religious fundamentalism.

The government announced new measures including a “day of secularity” after concerns were raised that some children – notably those from migrant populations – were failing to understand the “values of the republic”.

This month teachers complained that some pupils refused to keep a minute’s silence in respect for the 17 victims of three terrorist attacks two weeks ago. Some schools also reported that a number of Muslim pupils rejected the “Je suis Charlie” movement after the Charlie Hebdo attack, saying the satirical magazine’s drawings of the prophet Muhammad had insulted their religion.

Teachers are to be given training in transmitting republican values in an effort to stop young people dropping out of education and falling prey to extremists. Pupils will be given “civic and moral lessons” – including in civility and politeness – as well as “media instruction” as part of the scheme costing €250m (£190m) in the next three years. National “secularity day” will be on 9 December.

Gunmen Saïd and Chérif Kouachi were the French children of Algerian immigrant parents, while Amédy Coulibaly was born in France to parents from Mali. Last week the French prime minister, Manuel Valls, said the failure to integrate large populations from north Africa and elsewhere had led to a kind of “social and ethnic apartheid” in France. Government ministers have also spoken of “ghettos”, namely the grim housing estates of city banlieue where the migrant population is high as is unemployment and poverty.

Valls’ description has shocked France, where it is illegal to collect or collate information based on ethnic or religious background. Sébastien Sihr, secretary general of the teachers’ union SNUipp-FSU, said on Thursday: “In a fractured and ghettoised society, having a mix of [social] backgrounds is the only way to give pupils a real idea of how to live together.”