Stretch the plastic wrap or balloon over the cookie tin;
secure with rubber band(s) and sprinkle a few grains of uncooked rice over the
plastic. Hold the baking tray over the can. As the tray is being hit with the
wooden spoon, the rice can be seen moving and jumping over the plastic membrane.
This activity shows that sound travels in waves and reaches our ear drum or
tympani much in the same way as it vibrates the plastic over the cookie tin.