Background

Our eyes can only see a certain amount of pictures per second. They are actually quite slow. This is why we cannot see objects that are moving extremely fast. In this experiment we are going to use the slowness of our eyes.

You will need

• Paper
• Pencil
• Pens or colouring pencils to draw a picture
• Tape
• Scissors

What to do

1. From the paper cut two pieces with the same shape and size.
2. Draw two different pictures on the two pieces of paper that can also go together, for example a rabbit on one piece of paper and grass on the other. You could also do a bowl of water on one piece and fish on the other one. Or a bird on one piece and a tree on the other one for the bird to sit on.
3. Tape both pieces of paper on either side at the end of a pencil. The pictures need to face outside.
4. Now rub the pencils between your hands as if it was a stick that you want to light a fire with.
5. Look at the pictures.
6. You will see both pictures combined together, for example the rabbit sitting on the grass or the fish in the bowl.

The reason this works is that our eyes are too slow to follow the fast movement of the pictures and can only see a limited amount of pictures per second.

You can also watch this experiment as a video: