What inventions are related to children?

Harmonica is inspired by children. One day, a peasant girl in Germany was tired of playing with her mother's wooden comb at the door. She came up with a new trick, found two pieces of paper, put them on the wooden comb and put them to her mouth. Unexpectedly, she blew.

It happened that a musician passed by here. He was attracted by the beautiful sound. He carefully watched the little girl's masterpiece and then went home. He synthesized the little girl's wooden comb and made the first harmonica.