School's Out (2018) on Netflix

Plot summary

At Saint Joseph College, an experimental class of twelve gifted students has just seen its French teacher jump from the classroom window. Pierre Hoffman, a substitute, is put in charge of the group for the rest of the year. The class meets him with hostility and distrust, and behind it Pierre senses something violent in several of the students. Two hall monitors, Apolline and Dimitri, each lead a subgroup inside the class, and Apolline turns against Pierre. The students work on next year's material and keep apart from the rest of the school, gathering in ways that look to Pierre like rituals. He starts trailing Apolline and her followers once classes end.