A paper string spinner, or thaumatrope, is an optical illusion toy. It consists of a paper disc with a different image on each side that is attached to two pieces of string. When the string is twisted and the ends pulled apart, the disc rapidly flips, causing the two images to appear as one. The optical illusion is caused by the eye's ability to see an image for a fraction of a second after it has disappeared, which makes the two images appear superimposed. You can make your own paper spinner to see how the optical illusion works for yourself.
Draw a 3-inch-diameter circle with a compass on the card stock. Cut the circle out with a pair of scissors. Draw a lightening bolt on one side with yellow marker and outline it with black marker. On the other side draw the outline of white puffy clouds with a blue marker and colour in the area around it with the blue marker to make a sky.
Punch two holes into the centre of the circle for the string handles. Find the centre of the circle, and measure 1/4 inch away from either side of the centre point and punch holes with the hole punch.
Thread both ends of the 36-inch piece of string through the holes and tie the ends together. Slide the spinner over to the centre of the string. Hold the string of the spinner in your hands and twist it. Pull on the string with both hands and the paper will spin. The lightning bolt will appear superimposed over the blue sky.