The teacher, Samuel Paty, was beheaded in 2020 by an Islamist extremist after showing caricatures of the Prophet Muhammad to his students to illustrate free speech.
Another attack at a school, three years after the beheading of a teacher, has heightened anxiety about a new wave of terrorism in an already scarred country.
Troops were being mobilized and two major attractions were evacuated in separate alerts after a stabbing attack that killed a teacher and was described by officials as terrorism.