PARIS — Officials in France announced new measures on Thursday aimed at reinforcing secular values at French schools, after the terrorist attacks in and around Paris exposed serious cultural rifts between children in heavily immigrant communities and others in classrooms throughout the country.

Teachers are to receive new training, students would be exposed more deeply to civics and morals lessons, and classroom activities would include the singing of “La Marseillaise.”

The measures were devised to counter rampant “conspiracy theories” at French schools, the education minister, Najat Vallaud-Belkacem, said at a news conference Thursday. She said the issues had become apparent when some students refused to observe a moment of silence in schools after the attacks, which left 17 people dead.

French schools already have a secular code of conduct, but about 1,000 teachers and staff members would be trained on questions of “laïcité,” France’s secular identity, codified under a century-old law on the separation of church and state. She promised that a day devoted to secular laws would be celebrated once a year in every school.