Science 4th grade | UNIT 4: Sound 4.3 How sound travels?
Sound travels through different materials. But how does sound travel?
Activity 4.3 (Jumping rice)
You will need: plastic wrap - elastic bands - rice grains - an empty glass jar - a metal baking tray - a wooden spoon - a pencil
Put the plastic wrap over the top of the jar. Keep the wrap in place with an elastic band. Sprinkle a few rice grains over the wrap.
Hit the side of the jar with the pencil. What happens to the rice?
Hold the tin tray close to the jar and bang it with a spoon. What happens to the rice?
Predict what will happen if you clap your hands next to the jar. Try it out. Was your prediction correct?
Vibrations cause sounds
Sounds are made when things vibrate. A vibration is a very quick movement back and forth. You often cannot see vibrations, but you can feel them. Hold your hand in the middle of your throat and hum a tune. You will feel the vibrations and hear the sound.
Sound travels because vibrations travel
Why did the rice grains in Activity 4.3 move?
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Questions
1) Did you hear a sound when you hit the jar? Why?
2) Think back to the tin can telephone. Which materials vibrated when you used the telephone?