Eighth Grade · Science · week 20

Sound investigations

Describe sound as a wave requiring a medium, relate pitch to frequency and loudness to amplitude, and use an echo to estimate distance.

Sound is a wave of squeezed and spread-out vibrating particles, traveling through a medium like air, water, or a solid. Because it needs particles to pass its vibration along, sound cannot travel through the vacuum of space.

Pitch depends on frequency -- higher frequency means a higher pitch. Loudness depends on amplitude -- a bigger vibration sounds louder. Sound travels through air at about 340 m/s, fast but not instant, which is what makes an echo useful for measuring distance.

📋 For the teacher
Teach it (10–15 min):
  • Try a real echo test outdoors near a large flat wall, timing the delay with a stopwatch.
  • Use a stretched rubber band: plucking shows amplitude (how far it swings) separately from pitch (changed by tension or length).
  • Ask "what is vibrating?" for a few sounds (voice, guitar string, speaker) to reinforce the cause of sound.
Talk about it:
  • Why can sound not travel through the vacuum of space?
  • What is the difference between what pitch tells you and what loudness tells you?

Mastery looks like: They calculate distance from an echo's round-trip time and speed, and relate pitch to frequency and loudness to amplitude.

Common stumbles: Forgetting to divide the echo's round-trip distance in half; mixing up pitch (frequency) with loudness (amplitude).

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Records attendance + 15 min of Science for this learner.
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