I'm not sure why, but I think "childhood magic" when I think of these. "D'you wanna make a string telephone, Maddie? " "Yeah!" Then a pause, and somewhat skeptically, "Mom... how do the string ones even work?" "We ...are going to find out!"
I wasn't sure if our regular old kite string was going to work, but ring-ring-ring!.... it did just fine.
"Now," I said, "we need to poke holes in the bottom of these cups!"
I handed her a pencil. The pencil lead broke.
I handed her the paper clip end. Wouldn't poke through it. I handed her a needle. That wouldn't do it either.
Time for someone bigger to have a try!
It took some doing, but I finally got holes. Those were some sturdy cups!
She poked the string through the holes with the paper clip...
The sound waves travel through the bottom of the cup, out the hole, and all the way down the string and through the other cup. The sound waves travel faster and further by string than they do via airwaves! The cup amplifies the sound at the other end. After a few minutes of singing and silly play, Maddie switched places with me to see if mine worked just as well.