OBJECTIVES: The students will be able to describe what sound waves are and how a bat uses them to catch insects.
MATERIALS: Tape player, tape of soft music or other sounds, glass pie pan or clear container, water, eye dropper, over head projector.
1. Have students close their eyes. Play a tape of soft music or other subtle sounds. Have the children cup their hands behind their ears as they listen. Ask "Does cupping your ears help you hear the music better? How are your cupped hands like a bat's ears? Why do you think bats have such big ears?"
2. Fill the pan with about one inch of water. Place on the overhead projector. Turn the projector on and let the water settle. When the water is calm, drop a couple drops of water into it from the eye dropper.
3. What happened? Could you see the ripples move out from the source? What happened when the water waves reached the edges of the pan? Compare water waves to sound waves from a bat.
Courtesy Carlsbad National Park