Learners begin their exploration of sound by discovering its most fundamental truth: every sound in the universe starts with vibration. Through a series of hands-on demonstrations (plucking a rubber band near the ear, humming and feeling the throat, and watching a tuning fork in slow motion) students build direct physical evidence that sound and vibration are inseparable. The lesson puts that principle to work with a hands-on build: students construct a popsicle stick harmonica and use it to explore how changing the vibration changes both pitch, through frequency, and loudness, through amplitude.

Key Ideas

• All sound begins with vibration — rapid back-and-forth movement of an object.
• When vibration stops, sound stops. The two are inseparable.
• Frequency is the number of vibrations per second. Higher frequency produces higher pitch; lower frequency produces lower pitch.
• Amplitude is how far the vibrating object moves. Larger amplitude produces louder sound; smaller amplitude produces softer sound.
• Pitch and loudness are independent of each other. A sound can be high-pitched and quiet, or low-pitched and very loud.

Vocabulary

• Vibration: Rapid back-and-forth motion — the source of all sound.
• Frequency: The number of vibrations per second. Determines the pitch of a sound.
• Amplitude: How far the vibrating object moves. Determines the loudness of a sound.
• Pitch: How high or low a sound is, determined by its frequency.
  
  

Hands-On Activity: Build a Popsicle Stick Harmonica
Supply List

• 2 jumbo popsicle sticks
• 1 large rubber band
• 2 small rubber bands
• 1 plastic straw
• Scissors

Instructions

• Stretch the large rubber band lengthwise around one popsicle stick so it runs the full length of the stick.
• Cut a piece of straw about 1 inch long. Slide it under the rubber band near one end of the stick.
• Place the second popsicle stick on top. Wrap a small rubber band tightly around that end to hold both sticks together.
• Cut a second 1-inch piece of straw and slide it between the sticks at the other end.
• Wrap the second small rubber band tightly around that end. Your harmonica is ready.
• Place your lips over the large rubber band in the middle and blow gently to play.

Experiments: Move the straws closer together and blow again — notice how the pitch rises. Then keep the straws in place and blow hard, then soft — notice that the pitch stays the same while the loudness changes.

Supplies for Live Class (same for the experiment)

• Rubber Bands 
  • 1 larger flat rubber band 
  • 2 Smaller 
  • Various other sizes
• Two JUMBO popsicle sticks (the wider ones)
• Plastic Straw + Scissors to Cut it
• OPTIONAL: Stringed instrument, xylophone, bell, or tone-making item. Tuning fork is especially useful, but not required.

Discussion:

• What has to happen for a sound to be produced? Can you think of something that makes sound by vibrating?
• Why does sound stop when the vibration stops? What do you think would happen if something could vibrate forever?
• What is the difference between frequency and amplitude? How does each one affect the sound we hear?
• Can you make a sound that is high-pitched but quiet? What about low-pitched but loud? How?
• Imagine two guitar strings are vibrating. One vibrates very quickly but only moves a tiny amount; the other vibrates slowly but moves a lot. How would their sounds differ?
• What are some sounds in your environment that have a very large amplitude? What about very small amplitude?
• If you wanted to make a musical instrument higher-pitched without making it louder, what could you change?

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