Contents
Year 37 · Sound
KO

Year 3 · seventh unit

Sound

Sound is trembling. Put a hand on your throat and speak, and you can feel it tremble.

A child beating a drum

I beat the drum

A board to adjust

What happens if you put rice grains on it? Pull the drumstick back and let go to strike.

Rice grains jumping on a drum

I pulled a rubber band tight

A board to adjust

How does the sound change? Pull the band and let go to twang it, and drag the peg to change its length.

A hand twanging a rubber band stretched over a box

I called my friend on a string telephone

A board to adjust

What should join them so that it can be heard well?

Two children talking on a paper-cup string telephone

From here sound becomes a picture

What comes next in middle school · light and waves

Sound as a picture

It is the rubber band you twanged above. Draw the trembling as a line and it is a wave. Loudness and pitch show plainly in the shape of the line.

A sound wave drawn on dark paper

It is the rubber band from above

A board to adjust

This time the sound is drawn as a picture. Change the loudness, the tightness and the length.

5amplitude
— Hzfrequency

Back up to the basics