Thousands take part in rallies across France in honour of Samuel Paty, the teacher who was beheaded for showing cartoons of the Prophet Muhammad to his pupils.
People in the Place de la République in Paris carried the slogan “Je suis enseignant” (I am a teacher), with PM Jean Castex saying: “We are France!”
Thousands of people also gathered in Place Bellecour in Lyon to pay their respects, with another large turnout in Nantes.
Demonstrations are also being held in Toulouse, Strasbourg, Marseille, Bordeaux and elsewhere.
A man, Abdoulakh A, was shot dead by police on Friday after killing Mr Paty close to his school near Paris.
11 people were taken into arrest as part of the investigations.
No details have been given about the arrest. Four close relatives of the suspect were detained shortly after the killing. Six more people were held on Saturday, including the father of a pupil at the school and a preacher described by French media as a radical Islamist.
President Emmanuel Macron said the attack bore all the hallmarks of an “Islamist terrorist attack” and the teacher had been murdered because he “taught freedom of expression”.
The murder comes as a trial over the 2015 attack on Charlie Hebdo, a satirical magazine that has published cartoons of the Prophet Muhammad is underway.