Heinz Hafke

Erich Kubak is an excavator operator at the lignite plant. A technical weakness in the excavator, which repeatedly leads to production downtime, is causing problems for everyone. Erich works on an improvement, but this is not accepted by the chief engineer. On his own initiative, Erich carries out an experiment and causes a great deal of damage. He is dismissed as excavator operator and then resigns. Meanwhile, his son Ewald, who also works at the plant, manages to interest the chief engineer in his father's improvement proposal. Together they work on perfecting it. When Erich finds out about this, he returns to the factory.

Peter is unwilling to learn the multiplication tables at school. He would rather work as an acrobat at the circus, just like his friend Susanne. When the class plans a trip to the circus, Peter is supposed to buy the tickets. Since he miscounts and buys one ticket less than needed, he cannot join his schoolmates. Susanne, however, comes up with an idea and lets him work in the circus arena where he is supposed to check on the arithmetic problems of a numerate donkey. When Peter fails to control the donkey, he feels deeply ashamed and has to assess that math is needed in all parts of life.