A group of boys and girls swimming in a river separately. One boy decides to swim closer to the girls. One girl calls him fool. The other girls run out of the water screaming.
Ana (Betty Pierucci Berthoud, 12) is looking at herself in the mirror, her chest can be seen through her shirt, which she then takes off. Her brother, Léo enters the bathroom.
Janina Richter (12) pulls off her nightgown and has a conversation with her 13 year old classmate while topless, then sits back in bed partially covered with a blanket waiting for him to join her. This is immediately followed by a scene where it's daytime, Janina is sitting in bed and the boy's teacher, also topless, is on a chair between them.
A boy (12?) is using an anatomy book (probably) to explain a Frula (Filip Curic, 11?) something about the female reproductive system.
Once the book is closed, to the great surprise of the two, a woman (the boy's mother?) comes out naked from the bathroom.