This is a science kit with a difference! both sides of the wind-up clock are transparent, meaning that the workings of the clock are completely visible. So rather than being a tool to help children learn how to tell the time, this is designed to give them an understanding of how a clock actually works. They will be able to see how the swinging pendulum causes the different cogs and springs to rotate, move, turn the hands of the clock and make the bell chime too