This comedy is about one average family. The father works as master in the factory and his son is studying on high school. One day father must start to visit the evening school. It's the same school as his son visiting. The lives both students are connecting together. The son must teach the math and physics his own father. The father getting to know, that the life of the students is not simple as he supposed.
Sixth-grade pupil Katka daydreams during a math class about being Snow White and being freed by a prince who looks very much like Dzery from the eighth grade. Katka, her girl friends Lenka and Martina, and her fellow-pupils Franta, Joska and freckled Vrabcák, have spent five years going to the same little one-class school in their home mountain village of Pastvina. Their kind teacher Smetácek was very understanding about their games and fantasies, but he didn't teach them much about arithmetic. They are now laughed at for their ignorance by the strict Bidlo, their new teacher at the near-by little town. As he does every year, Smetácek is preparing a theatre performance with the local children. Katka suggests the fairytale about Snow White
