Box Guitar
Word of the day: vibrate
“Let's make a guitar out of junk and find out where sound comes from.”
Grab
- a tissue box or shoebox with a hole cut in the lid
- 4 rubber bands, thick and thin
- a pencil to lift the strings
Do
- Stretch the rubber bands around the box over the hole. Pluck one. Watch it blur while it sounds.
- Touch it to stop it. The sound stops too.
- Pull one band tighter and pluck it. Then a thick band and a thin band.
- Slide a pencil under the bands near one end to change the sound again.
The big moment
Watch the band blur while it sings. Touch it and the sound dies.
Ask (guess first, then try)
- What's the band doing when it makes sound?
- Which is higher, the tight band or the loose one? The thin or the thick?
What's going on (for you)
Sound is shaking: the band vibrates, shakes the air, and the air shakes your eardrum. Tighter and thinner strings vibrate faster, and faster shaking sounds higher. That's how a real guitar is tuned.
If they want more
Hum with a hand on your throat to feel your vocal cords vibrate. Fill glasses with different amounts of water and tap them.
Look it up
Wikipedia: Sound PhET simulation