The afternoon children studied sound. We decided to experiment with how sound travels through a string. We rigged up the old tin can experiment. This worked pretty well but then each child made one to take home.
These actually worked much better than the tin can set. It fit well over the ear and when pulled tight, you could hear what the other person was saying! We learned if the string was not "taut" the sound would not travel well. Also, if your hand is touching the string, the sound does not get to the other side.