Sound Lab

Little levels (ages 4 to 6)

1. Tap and listen Three glasses: find the lowest and the highest sound.
2. Make it higher Pluck a rubber band, tighten it, and hear it go up.
3. Big drum, small drum Hit both and say which one is lower.
4. See the sound Rice on a drum jumps higher when you hit harder.
5. Play the tune Tap the glowing glass to play a seven-note tune.

Big levels (ages 7 to 9)

1. Order the glasses Drag five glasses into order from lowest to highest and play them.
2. Make a scale Change the water in three glasses until they play C, E and G.
3. Loud or high? Match a dotted sound wave with a loudness knob and a pitch knob.
4. Sound needs air Pump the air out of a jar and the bell inside goes silent.
5. Blow or tap? Tapped, a full bottle is lower; blown, it is higher.

The big ideas

• Sound is a wobble. Everything that makes a sound is vibrating: a drum skin, a glass, the air in a bottle, your throat. The vibration travels through the air to your ears.

• Fast wobbles sound high, slow wobbles sound low. Tight, short, small or light things vibrate quickly and sound high. Loose, long, big or heavy things vibrate slowly and sound low. More water in a tapped glass makes it heavier and lower.

• Big wobbles are loud. Hitting harder makes the skin move further, which makes a louder sound and a taller wave. Loudness and pitch are two separate things.

• Sound needs something to travel through. Air, water and solids all carry sound; a vacuum carries none. That is why space is silent and why you hear your own voice differently through the bones of your head.

• Blowing and tapping use different wobbles. Tapping a bottle vibrates the glass (more water, lower). Blowing across it vibrates the air column (less air, higher), which is how flutes and bottles make notes.

Try it at home

1. Glass xylophone Line up five glasses with different amounts of water and tap them with a spoon. Add or pour out water until they play a tune.
2. Rice on a drum Stretch cling film over a bowl, sprinkle rice on it, and bang a tray nearby. The rice jumps without anything touching it.
3. String telephone Connect two paper cups with a long tight string. Sound travels along the string much better than through the air.
4. Bottle band Blow across the tops of bottles with different water levels, then tap them. Notice that the rule flips.

Ask after playing

• Which glass made the lowest sound, and why?
• What did the rice do when you hit the drum harder?
• Why did the bell go quiet when the air was pumped out?