How to Make Cup Phones

Telephone booth

Building a telephone out of paper cups and string takes only a few minutes but can provide hours of entertainment for children. It will also teach them how traditional telephones work. The paper cup phone uses the scientific principle of sound waves. Talking into one cup creates vibrations that travel through the string to the second cup and reproduce the words and sounds of the speaker at the other end.

Things You'll Need

• 2 paper cups, 8 oz.
• 30 feet kite string
• No. 1 sewing needle
• Cellophane tape

Instructions

1. Poke a small hole in the center of the bottom of two paper cups using a sewing needle.

2. Thread the string from the outside in through the hole in the bottom of one of the cups. Tie a knot on the inside end to prevent the string from being pulled back out of the hole or use tape to secure the string to the inside of the cup. Repeat the process for the other cup.

3. Stretch the cups apart making sure the string is tight to ensure the best transfer of sound. Begin having conversations using the paper cup phone.

Tips & Warnings

• Experiment by substituting different types of string to discover which works best as a transmitter of sound.

• Tin cans and plastic cups can also be used to create a cup phone.