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Indoor activity

Paper Cup String Telephone

Build a classic string telephone and discover how sound travels through solid objects to talk to your friends from another room!

Ages 3-12 0-1 hours Education 8/10

Materials

  • Paper Cups
  • Push Pin
  • Scissors
  • String

Illustrated Steps

1

Poke the Holes

Have an adult use a push pin to make a small hole in the centre of the bottom of each cup.

2

Thread the String

Thread a long piece of string through the holes in both cups, going from the outside to the inside.

3

Knot and Secure

Tie a large knot at each end of the string inside the cups so it doesn't pull through.

4

Test the Line

Pull the string tight between two people. Speak into one cup while the other person listens!

What You’ll Create

Ever wondered how sound travels? 🗣️ Build a Paper Cup String Telephone and find out! By connecting two Paper Cups with a long piece of String, you can send your voice across a room. The string vibrates as you speak, carrying your secret messages like magic to your friend’s ear.

How to Set It Up

Step 1: Poke the Holes

⚠️ Adult Helper Needed — An adult should use a Push Pin to poke a small hole exactly in the centre of the bottom of both Paper Cups. Make sure the hole is just wide enough for the string to pass through.

Step 2: Thread the String

Cut a long piece of String (about 5–10 metres). Thread one end of the string through the hole in the first cup, going from the outside to the inside. Repeat with the other end of the string and the second cup.

Step 3: Knot and Secure

Tie a large, thick knot at each end of the string inside the cups so it can’t pull back through the holes. You can tie the knot around a small piece of a toothpick or a paperclip if the hole is a bit too big.

Step 4: Test the Line

Give one cup to a friend and walk apart until the String is pulled completely tight. This is the most important part — if the string is loose, it won’t work! Take turns speaking softly into your cup while the other person holds theirs to their ear.

Have fun!

  • 🤫 Try whispering as quietly as you can and see if your friend can still hear you.
  • 🚪 Go around a corner or into another room to see if the telephone still works (just don’t let the string touch the wall!).
  • 🎻 Gently pluck the tight string like a guitar string and listen to the ’twang’ through the cup.
  • 👫 Add a third cup in the middle of the string to see if you can have a three-way conversation!

Why It’s Amazing

  • Acoustics Basics: Teaches children how sound is actually a series of vibrations that can travel through solids like string. 🔊
  • Communication Skills: Encourages clear speaking and active listening between partners. 🗣️
  • Scientific Method: Invites kids to experiment with string tension and length to see what works best. 🧪
  • Collaborative Play: A perfect activity for siblings or friends to do together. 🤝

Pro Tips

For ages 3-5: Keep the string shorter (2-3 metres) so they can still see each other easily. Emphasise that the string must be ‘straight and tight’ like a bridge.

For ages 5-8: Experiment with different types of string (wool, fishing line, cotton thread) to see which one carries sound the best.

For ages 8-12: Challenge them to explain why the sound stops if you grab the middle of the string while someone is talking!