Two completely different sons grow up in the same family. The youngest, Frol Kalitkin, is an exemplary seventh-grader, winner of Olympiads, the first student. And the eldest, Andryusha, is a loafer, a loafer and a dude. The “correct” Frol takes up the upbringing of his brother.

A boy decides to stay in sixth grade for another year in order not to be separated form the girl he's in love with.

After being hired as a temporary substitute for an experienced pedagogue, a young maths teacher has to find common ground with a precocious group of sixth graders.