French schools reopened Monday for the first time since the beheading of a teacher who opened a class debate on free speech by showing students caricatures of the prophet of Islam, in mourning and under tight security for a national homage.

Samuel Paty was killed on Oct. 16 outside his school in suburban Paris by an 18-year-old refugee of Chechen origin to punish him for showing the caricatures published by the satirical newspaper Charlie Hebdo, which triggered a newsroom massacre by extremists in January 2015.

Since their re-publication in September at the start of the ongoing Paris trial over the killings, France has endured three attacks blamed on Muslim extremists: one by a Pakistani refugee that injured two people outside the newspaper’s old headquarters, the slaying of the schoolteacher, and a deadly knife attack last Thursday in a church in the Mediterranean city of Nice. All three have prompted terrorism investigations, and France is now at its highest level of alert.

French President Emmanuel Macron promised to increase protection of schools and churches immediately after the Nice attack, more than doubling the number of soldiers actively deployed in the country. Paty was killed at the beginning of a two-week French school holiday.

On Monday, the school where he taught at Conflans-Saint-Honorine reopened for teachers only. France’s prime minister, Jean Castex, arrived to lend support. Other schools throughout the country resumed as usual to both students and teachers.

At schools throughout the country, students will read the letter of Jean Jaurès, a 19th century French thinker and politician, to instructors urging them to teach the country’s children to “know France, its geography and its history, its body and its soul.”

Macron has defended the decision to publish the caricatures, which he says falls squarely into two of France’s most cherished rights: freedom of expression and secularism. The cartoons were originally published in Denmark in 2005 and elsewhere later in countries where freedom of expression is considered inviolable. Many Muslims see them as sacrilegious.

“We have the right to believe that these caricatures are in bad taste. There are plenty of people I believe are in bad taste. There are plenty of people who I think say idiotic things,” Gerald Darmanin, France’s interior minister, told BFM television. “But I’ll defend to the death your right to say them, as Voltaire said.”