The eye is a complex and important part of human anatomy and understanding how it works is a fundamental part of education for many students. It is simple to make a functional model of the eye to demonstrate how the eye works and show how an image is flipped from the retina to how we perceive it.
Mix a paper mache mixture. Take 1 part flour and 5 parts water, then mix and boil it together for about five minutes.
Blow up the balloon and with a permanent marker, draw a circle with a diameter of 2 inches on one end and a larger circle of 3 1/2 inches on the other end.
Cover the balloon with paper mache, leaving the circles untouched. To cover the balloon with paper mache, take 1-by-5-inch strips of newspaper and coat them in the mixture. Cover the balloon with three layers of strips, making sure that it is smooth. Let it dry overnight.
Pop the balloon, cover the small hole with aluminium foil and tape it in place, making sure there are no edges that will let the light come in. Poke a small hole in the centre of the foil.
Cover the larger hole with waxed paper and tape it in place. Make sure that all edges are covered so that no light can get in.
Paint the eye over the newspaper, foil and waxed paper.
Mount the eye on a piece of wood with modelling clay. Take a large clump of clay and glue and mould it into the base of the eye. Glue it onto the wood base.
Going into a dark room with one window open will demonstrate the way that the eye works. Place the model in front of a window and the images outside will be upside down on the waxed paper, just as they are on the retina.
Smooth out the paper mache while still wet to get a nice eye shape.
Be careful when handling the dry project; the shell is very delicate.