# Waves of Sound  Mystery 3

In this Mystery, students discover that sound is a wave. In the activity students model the relationship between a sound’s wavelength and its pitch.

## Why are some sounds high and some sounds low?

Beginning Exploration (1 of 10)
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Beginning Exploration (2 of 10)

DISCUSS:

What do you think--what makes one sound LOWER and another HIGHER?

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Beginning Exploration (3 of 10)
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Beginning Activity: Making Waves
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Beginning Exploration (4 of 10)

Get a copy of this worksheet and fill in the two questions you just discussed. (You’ll answer the other questions later.)

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Beginning Exploration (5 of 10)
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Beginning Exploration (6 of 10)

DISCUSS: How would you describe the differences between the high-pitched and the low-pitched sound wave?

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Beginning Exploration (7 of 10)

Circle which words you'd use to describe the high-pitched wave versus the low-pitched wave:

Note: Be sure to play with the online oscilloscope we link to in the Extras!

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Beginning Exploration (8 of 10)
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Beginning Exploration (9 of 10)

DISCUSS:

Which of these is the HIGHEST pitch? Explain how you know.

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Beginning Exploration (10 of 10)

DISCUSS:

Which of these is the LOWEST pitch? Explain how you know.

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Beginning Activity Prep
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# Making Waves

In this mystery, students draw the waves that different sounds make on an oscilloscope, a machine that shows a picture of a sound as waves. Then they vibrate a rope to make waves that look like the ones made by the oscilloscope.

For the rope activity, you’ll need a smooth hard floor where you can stretch out a rope that’s 12 to 15 feet long. Students can take turns making waves. We suggest having at least one rope for each group of 8 students.

# Step 2: Get supplies.

For each group of students, you’ll need a flexible rope measuring 12 to 15 feet in length. Jumpropes work well. Or you can use a rope like this. One teacher we know makes wonderful waves with phone cords like this one..

Each student will also need:

For your own use, you will also want to print:

# Step 3: Follow up after class

If you have a computer that uses Chrome and Firefox to browse the Internet, use the online oscilloscope in Extras to extend your exploration of the patterns made by sound. Using this tool, students can see the patterns made by sound they make. Great science content and lots of fun.

Beginning Complete!

You've completed the Exploration & Activity!

If you have more time, view the assessment, reading and extension activity in the optional extras.

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# Optional Extras

###### Below are ideas for extending this topic beyond the activity & exploration you just completed.
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“Now Hear This!” describes the invention of a sound maker designed to repel kids & discusses sound waves. This Common Core-aligned reading is free with registration on ReadWorks. It includes comprehension questions to be downloaded separately.

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### Online Tool: Bouncing Balls

Can you be so quiet that that this online sound detector doesn't even know you're here?

When you open this online tool, choose "Begin Bouncing" and then click on the picture of a microphone. A screenful of balls will bounce whenever your computer's microphone detects a sound. Start by clicking here.,

For an extra challenge, select “emoji” and set bounciness to the max. Now try to keep those balls from bouncing!

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# Hearing Test

Use this online test to find the highest and lowest pitch you can hear.

• The video starts with a tone so low you probably can't hear it. Keep listening.
• When you do you start hearing the hum? Notice when it gets so high you can't hear it anymore.
• While you're listening, watch the waves. They change with the pitch — from long wavelengths to short.
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### Oscilloscope Experiments

Here are 3 experiments to try with the oscilloscope:

1. Sounds that are a mix of pitches make messy waves. Can you find a sound that makes a simple wave? (Try whistling.)
2. What happens to the oscilloscope picture when you make a sound louder or softer?
3. What happens when you make a sound higher or lower?
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### Oscilloscope

Get ready to see sound. This oscilloscope only works in Chrome and Firefox and it requires a microphone on your computer.

When you click this button your browser will ask you permission to use the microphone.

Look at the top of your screen ☝️

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The pitch of a sound — how high or low it is — depends on the vibration that made the sound. The quicker the vibration goes back and forth, the higher the sound.

On this singing road, the vibrations of a car play a tune. Bumps in the road called rumble strips make the car vibrate.

Play the video, then discuss: Which set of rumble strips plays the higher note?

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# Image & Video Credits

Mystery Science respects the intellectual property rights of the owners of visual assets. We make every effort to use images and videos under appropriate licenses from the owner or by reaching out to the owner to get explicit permission. If you are the owner of a visual and believe we are using it without permission, please contact us—we will reply promptly and make things right.

Exploration
"the mosquito" by LadyofHats , used under CC BY
Schlieren by NASA , used under Public Domain
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