Did you ever play with string phones as a kid? We did, however I remember making them out of paper cups at the time. My sister reminded me of this project the other day when she was telling me how her and a fellow teacher made some string phones to talk between their classes. As soon as she told me the story I knew I had to make these with my girls.
Since my sister is a Science teacher at a High School, she told me that the Physics teacher told her that the phones would work better if made out of tin cans. So I decided that is what we would make ours out of. The tin can phones are also much studier than the paper cups so with my wild children they are sure to hold up a LOT longer.
I let each girl pick a color to paint their can so that they knew which was which (don’t ask me why that matters but with my children it does). After the paint dried I attached the string and let the girls talk on their new phones. They both thought it was pretty cool that they could hear each other from so far away. My hubs and I both had to use them too, because it is just too fun not too!
As far as the Science lesson, I told the girls about sound waves and how their voices travel along the string to the other can so that the person with the other can can hear them. We also tried it with the string very loose to see if it would work and it did not, so then we talked about how the sound travels on the string and if it is not tight the sound can fall off. Okay that may not totally be the science way of it but for a 2 and 6 year old they understood it better that way.
What is happening with this experiment?
When you speak into the can you create a Sound Wave, which is then converted into a vibration that travels along the string and then converted back to a Sound Wave in the other can. This experiment can be done with paper cups, however the tin cans are better conductors and you can usually have better sound by using them, they also hold up better over time so you can continue to use your phones.
2 Tin Cans (cleaned soup or veggie can work great)
Hemp String (cut to desired size)
Hammer and Nail
Use your Hammer and Nail to make a hole in the bottom of each can.Put your hemp string through the bottom of each can.
NOTE: You can make the string as long as you like.Tie a knot in the string to keep it from falling out of the can.
Have one child talk into one end of the canLet the other child Listen with the other can.
NOTE: To work the string needs to be pulled tight so the sound vibrations can travel from one can to the other.