A large button or coin, string, paper and a small piece of sticky tape.

Cut 2 circles out of the paper to the exact same size as the button or disc object. Cut a piece of string to approximately 50cm long then attach one end to the disc using the tape. Glue a paper circle to each side of the disc. Draw part of a complete picture on one side and the corresponding part on the other. Wind the disk up then dangle it from the string so that it quick unwinds, or flick it with your finger to spin it. You will see the complete picture made up from 2 separate drawings.

We have used the classic 'Bird out of a cage' and "Bird in the cage' picture but you should think of one of your own. You can also use writing to make a complete sentence for example 'I' and 'You' on one side then 'Love' on the other. Almost any picture can be broken into two parts but it helps if they each mean something on there own as well as complete.

This project is know as an 'Optical illusion' because it tricks your eyes into thinking there is a whole picture when in reality you are looking at two separate pictures.