Musical Car

Children interact with the toy by pushing the car with their hands, and listening to the music produced by the music box inside. They can also open the toy car from the bottom to replace the music box inside with one with another tune, thus giving them insight into how the toy works and produces music. It can also be used as an adult desk toy.
Based on the idea of motion in general, but more specifically focuses on speed, velocity and acceleration. This is taught through observing the toy car, but also by listening to the tempo of the music produced when the car is pushed.
This toy would most likely not cost very much to produce, as its parts are entirely mechanical and are relatively simple. The exterior of the toy car is to be made out of wood, so it would be quite durable as a toy in the long run. Although the toy has small parts inside, the parts that children interact with are not small enough to be swallowed, so it is quite safe as well.