Close the bag. Repeat steps 1 and 2 using a plastic container and a metal can. Fill a glass jar nearly full of water. Put the other ear against the glass jar. Ask another student to hit two spoons together under water.
Sound travels through different kinds of matter.
Sound travels through gases, liquids and solids. Hold a plastic bag of water against one of your ears. Cover your other ear with your hand. Have someone hold a ticking clock against the bag of water. Keep the clock in the same place.