The book contains five simple and interesting projects to create active entertaining devices from improvised materials - a fountain, a frog, a mousetrap, a gyroscope and a kaleidoscope. Children will not only have an interesting and exciting time, but will also acquire useful skills in working with hand tools and simple materials, as well as in a playful way in practice, they will get acquainted with the physical principles underlying the work of real prototypes of the assembled models.