Build

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Here are some of the materials you can use

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Prepare ahead of time

Have paper and pencil ready to write down ideas and sketches as you design.
Think about stringed instruments you know and how they make sound. (Banjo, guitar, harp, violin)
Think about things you know that vibrate, or move rapidly back and forth. (Rubber bands, vocal chords, washing machine, water)
TIP: To feel your vocal chords vibrate, touch your throat with the tips of your fingers as you hum a song. Then sing a loud song and feel how the vibration movement changes.

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Think about the challenge

How are the vibrations in your vocal chords related to sound?
Why do vocal chords feel different as you change the pitch of your voice?
How are musical sounds made? Other sounds?
TIP: The rapid vibrations of the vocal chords cause sound waves that travel out through the mouth and into the air. Vibrations are what make sounds.
TIP: Vocal chords tighten to produce higher-pitched sounds and relax to produce lower-pitched sounds. They vibrate at a higher frequency, or rate, for higher pitches.
TIP: Inventors are always looking for ways to improve things or meet people’s needs—including making music! Music is important to people and learning how to make different sounds in music is fun and exciting.

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Think about and write down your ideas

Why does a child’s voice have a higher pitch than an adult’s voice?
How can you make the pitch of a rubber band higher?
How can knowing about vocal chord vibrations help you create different pitches with your rubber bands?
TIP: A vocal chord’s length depends on the size of a person’s throat and changes as a person grows.
TIP: Something that vibrates at a faster rate will have a higher pitch.

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Look at the materials

Will the box make better sounds with the lid on or off?
Will you use rubber band loops or open strips for the strings on your instrument?
How will you attach the strings and keep them securely in place while you play?
How will you make a high-pitched sound? A low-pitched sound?
TIP: A thicker rubber band will make a lower pitched sound than a thinner one as long as both rubber bands have the same tightness and length.

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Design and build the instrument

Decide whether your instrument will have a lid or an open top.
Decide what direction your strings will run across the box.
TIP: The length of the rubber bands will affect the pitch. Short, tight, thin rubber bands will produce lower pitched sounds.

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Design and build the instrument (continued)

Choose the rubber bands you want to use as strings.
Decide how you are going to attach your rubber-band strings to the box.
Attach the strings.
TIP: You can slip rubber bands around a box or you can cut the rubber bands open to make strips to poke through holes in the box or to tape on the outside of the box.
TIP: If your rubber bands slip out of place, try attaching by taping them on the side or bottom of your instrument.

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Test the rubber bands’ pitch

Sweep your finger across each string or pluck each string to test the sound.
Modify the design if you don’t hear a different pitch from each rubber band.
TIP: If the box top is interfering with how the rubber-band strings vibrate, make a bridge by slipping pencils or craft sticks under the strings to raise them off the surface.
TIP: To get a louder sound, try removing any extra tape or making the bridge less bulky so you can increase the vibrations—and the sound!
TIP: If you have trouble getting a low pitch, try stretching out the rubber band to make it slightly longer.
TIP: A rubber band’s thickness, length, and tension will affect the pitch it makes. You might want to test and revise your rubber band selections to get different pitches. Testing and revising a design is part of the design process.

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Play a tune

Pluck the strings.
Play a favorite tune and sing along.
TIP: If your strings slide out of the tape while you are plucking, try tying a paper clip to the bottom of each side and tape over the clip so the rubber band can’t slip through the tape.
TIP: If you want to increase or decrease the pitch on all strings, try raising or lowering the height of the bridge.

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Did you know?

The String Family
An orchestra is a large group of musicians who play together. It is made up of lots of different instruments. The biggest group of instruments is the string family. It’s called a family because, just like all families, there are things that are the same about all of the instruments. One of those things is the way their sounds comes from the vibrating strings.

There are small, high-pitched violins and violas and big, low-pitched cellos and double bass instruments. When you look at a string instrument you might wonder why it is called a string instrument—because most of it is wood. The strings are important because they make the sound. But it’s the big or little wooden body—which is hollow—that lets the sound vibrate inside.

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Try this next!

Try building a 12-string guitar. Add strings to your instrument and see how many different pitches you can create.
Compose a song. Add more notes to your tune. Press fingers along a string to change the length of the string. When you find the sound of a note you like—mark the string. Then use your favorite notes and write words to go along with your tune!

Build an Instrument