Students will learn that sound is produced by vibrations and how the tension, length, and thickness of a vibrating string affect the pitch of the note produced.
Stiff paper cups, fishing line or string, paperclip, pushpin
Sound travels through the air as a pressure wave, and guitars produce sound through the vibration of strings. The string vibrations alone do not move enough air to be heard by an audience, however. In order for the sound to be heard, the vibrations of the strings must be amplified.
Acoustic guitars have a large, hollow wooden body. When the strings vibrate, those vibrations are passed along to the wood. The large amount of vibrating wood vibrates the air inside the guitar, creating sound waves. The sound is projected out through the hole in the guitar's body, allowing the audience to hear it.
Use a pushpin to poke a hole in the bottom of the cup, as close to the center as possible. Cut a length of fishing line about 18" long and tie a paperclip to one end. Feed the free end of the fishing line through the opening of the cup and through the hole you poked. Hold the cup in one hand and the end of the string in the other; pull the string taut and pluck it with a finger to make sounds.