For the first time ever, Voltaire High welcomes girls, 11 freshmen; Vice-Principal Bellanger and his wife Jeanne, the school nurse, soon have to deal with the unforeseen excesses of coeducation.

It's the freshman's first Physical Education class, with its share of surprises for the girls; It's the day of Bellanger's nephew's disciplinary board hearing, and he needs to keep a close eye on Miss Couret, the new English teacher.

The students pair up to do an exposé; Simone is glad to see Jean-Pierre when working at Michèle's, who hopes to finally get a good grade; Annick meets her mum's new boyfriend, but is wary of him.

Bellanger is excited to be back in at school again after the Christmas break, but the boys are restless; it infuriates Michèle, who'd like to know what makes you blind and can't stand being treated like a little girl.

Jeanne, the school nurse, goes to the theater with Denise where she meets Irène, an actress who deeply moves her; Denise crosses paths with Bellanger, who walks her home and confides in her about his love life.