String Telephone

My kids loved making their own toys, and creating something out of nothing.  We were reminded of this simple DIY string telephone from a thrift store experiment book.  I remember making one of these when I was a little girl.  Take a step back in time an make a fun string telephone with your kids and learn how sound travels!

To make your own String Telephone, you will need:

• 2 plastic or paper cups – a tin can works great too
• String (you can experiment with different lengths)
• A friend to old the other end of the string telephone:)

Simply make a small hole in the bottom of both cups.  Thread your string through the cup and tie a knot to keep the string from pulling back through.  That’s it!  You are all ready to start playing.

You take one cup and your friend takes the other.  Walk far enough apart to make the string tight.  Depending on how long you cut your string will depend on how far you need to stand apart.  Also, make sure that the string is not touching anything else.

One friend holds the cup to their mouth and talks, while the other friend holds it to their ear and listens.  The girls were amazed at how clear each other sounded.

Why your simple string telephone works:

When you speak into the cup, it creates sound waves which vibrate the bottom of the cup. The vibrations move along the tight string into the bottom of your friends cup.  When they reach the 2nd cup the vibrations are turned back into sound waves.  This is how your friend is able to hear what you are saying.

Also try these fun variations:

• What is the longest string that can make the string and still hear your friend?
• Does it make a difference to use a tin can, paper cup or a plastic cup?  What if you change the size of the cup?
• Can you use two different size cups, one on each end?
• Use fishing line instead of string, what happens?

Here is a link to a fun list of great experiments that my kids love.

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