A standing (or stationary) wave is a wave that appears to stay in the same place. To make one, find a skipping rope and a friend. Get your friend to hold one end still whilst you spin the other end.
Find some polarising sunglasses. You need at least two pairs (or take the lenses out of one so you have two separate polaroids). Place one lens on top of the other.
For this you will need two large plastic bottles, a washer and some tape.
Try putting a light ball (ping pong balls work well) into a stream of air blowing straight up from a hairdryer. (Make sure it’s on a cool setting!) Once the ball ‘balances’ try lowering the angle of the stream of air.
Connect a camera to a TV screen so that the screen shows the camera’s view. You could use a web-cam and computer screen instead. Point the camera at the screen. What sort of patterns can you make? Try playing with the lighting and film at different angles.