Walkie-talkies

What to do:

1. Punch a small hole in the bottom of two paper cups.
2. Attach a string from one hole to the hole in the other cup. Tie knots at both ends to hold the string in place.
3. Allow children to carefully pull the string tight, and to talk to each other using the cups. The string carries the sound from one to the other.
4. Try with different types of string or with a string loose instead of tight. Compare the results.