Listen carefully. Can you still hear the timer when it is under this towel?
It was still there, just quieter. So materials must be doing something to the sound.
Some materials let sound through easily. Others muffle it. Today we will find out which materials muffle sound best, using a fair test.
Whisper to your partner: which wrapping will muffle our timer best, a thin sheet or a thick soft layer? Be ready to share one idea.
When we covered the timer, the sound got quieter. That quieter sound is muffling. Sound is a vibration that travels through materials to our ears. Choosing materials on purpose to cut noise is soundproofing.
Our theme: which materials muffle a sound best?
With your group, choose three materials from the tray to compare. Predict which will muffle the timer most, and say why. Predictions are the start of the science, not a test to get right.
Look at the five cards on screen: the wrapping material, how muffled the sound is, the sound source, the listening distance, and how tightly it is wrapped.
Help us sort them. What do we change? What do we measure? What must stay the same to keep the test fair?
When the cards are sorted, write on your Investigation Journal page: your three materials, your prediction, and how you will judge muffling (our class 1–5 scale or rank 1st–3rd). Keep it short so you are ready for the stations.
Which material muffles the sound best?
Your group will test at a listening station when it is your turn. While you wait, prepare your three wraps and keep your Investigation Journal page ready.
Class muffling scale (higher = more muffled): 1 = almost as loud as bare, 2 = a bit quieter, 3 = clearly quieter, 4 = hard to hear, 5 = barely hear it. Or rank your three materials 1st–3rd.
1. Start the timer with no wrap and listen from the mark (your baseline).
2. Wrap it in your first material. Keep the wrap about the same tightness each time.
3. Listen from the same marked distance, agree one muffling score, and jot it on your Investigation Journal page straight away.
4. Repeat for your other materials. One agreed score per material is enough.
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