Tin Can Telephone

Materials you will need:

* String

* 2 Tin Cans

* Masking Tape (optional)

* Very Small Philips Screw Driver

Steps:

1.) Wash both tin cans out with soapy water and dry them. Make sure that the openings of the tins are not sharp. If they are, secure masking tape along the opening.

2.) With adult supervision - make a hole in the bottom (middle) of each tin can using the small screw driver. Make sure that you make a very small hole.

3.) Cut string long enough so that you can reach different rooms or reach a long distance in the yard.

4.) Thread the string through the hole at the bottom of the tin can so that the string has entered the inside of the tin can. Tie a knot big enough so that the string stays inside the  can. (You can also tie the string to a paper clip or toothpick to prevent it from slipping out of the cup/can.)

5.) Repeat step 4 with the other tin can.

6.) Hold one tin can and have someone else hold the other tin can. Walk the distance of the string so that the string in tight (not dangling).

7.) Have one person hold the opening of the tin can over his/her ear while the other person speaks into the opening of the other tin can.

Why it works: 

When one person talks into his/her can, the bottom of the can vibrates back and forth with the sound waves. Imagine the bottom of the can moving back and forth very quickly (1,000 times per second or more) with the sound waves of the speaker's voice. The vibrations travel through the string by pulling the string back and forth. Therefore, the bottom of the second cup should start to vibrate back and forth just like the bottom of the first can is vibrating, producing sound waves. The second person can hear the sound waves and, therefore, hears what the first person says.