On Tuesday, we understood that sounds are made as a result of vibrations. We used homemade telephones to help us understand how this concept works.

We learned that when you speak into the cup, the back of the cup vibrates. The vibration extends the string and the sound waves, or vibrations move through the string. The telephones worked better when the string was tight because when the string is loose, the noise is softer (soft materials tend to absorb more sound that solid ones). When more sound is absorbed, your friend on the other end of the line can’t hear as well.