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The Kid Should See This

The Science Behind String Telephones

String telephones might be one of the best kinds of toys to make and play with when social distancing with friends: You get to talk and play while mixing in a bit of science and a lot of distance. Learn how to make a string telephone with two cups and some string with this classic demonstration from outreach educator Brad Alston from the Oregon Museum of Science and Industry in Portland.

What’s going on when you talk is that you make sound waves that move through the air and then vibrate in other people’s ears. When you hear a sound you’re hearing a vibration that is moving and wiggling through the air.

When you make a string telephone, you talk into it causing the bottom of the cup to vibrate and that vibration travels along the string to the other cup where they can hear the sound of your voice coming out of their cup.

Experiment with materials: Different kinds and sizes of cups, different lengths of string, twine, yarn, dental floss, or whatever you have around the house. Or tie in a third string and cup. Will it work?

string telephone demonstration
OMSI educators have made so many smart science education videos for kids and adults who can’t visit the museum. Watch them all here on OMSI’s YouTube Channel.

Previously from OMSI: Sugar rainbow in a straw, a density science activity. Plus, more easy kid experiments:
• How to extract iron from your breakfast cereal
• How to capture a scent
• How to weave yarn on a mini cardboard loom
• How to make play dough, a chemistry experiment

And more videos about sound:
• Sound is a vibration, a demonstration
Odyssey of the Ear, an animated tale of sound
• What does sound look like?

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