To create an image of a bat on the wall of a dark room, cut out an inch-long bat from a square of black paper, center it over a flashlight and tape to secure it in place. Hold together two identical magnifying lenses in front of the light and experiment until you get the right focus on the wall. Cut a piece of a cardboard tube to fit the correct distance between the flashlight and the lenses, tape the apparatus together and set on a table.