This one is so easy and can be done with objects you find around the house, but also has scope for investigating as you can try out different things to see if you can make the sounds louder, deeper, higher etc.

What you need:

Either:

• Tissue box (essential – can be any kind of small box but tissue boxes are great as they have a ready made hole!)
• Elastic bands (essential – you only need a couple but they do need to fit over the box).

or:

• Jam jar with lid (essential)
• Dried beans (essential – can be beans or lentils or pasta or a selection of all of these!).

What to do:

If your box doesn’t have a hole in the top then cut out a oval shaped hole in one side of the box. Get your little one to stretch the elastic bands over the hole, making a kind of tissue box guitar, and then ping them to see what happens. Try pinging the bands gently and really hard.

Half fill jam jar with dried beans. Shake. It’s that simple!

Tips/extra bits:

• If you have elastic bands with different thickness then you can get older children to put them on the box in size order. Investigate what happens to the sound when you pluck each different thickness.
• Pop a small cloth rolled up in the hole of the tissue box guitar and then pluck the elastic bands. What happens to the sound now?
• Get a small bit of cardboard and wedge it between the bands and the box (like a bridge of a guitar). See what happens to the sound now.
• Wrap a cloth around the jam jar to see what effect this has on the sound.
• If you have several jam jars you could put different amounts or different dried items in each jam to see if different sounds are made.

The science bit

An object making tiny movements, or vibrating, can make sound. When you pluck the elastic band it vibrates and then makes the air around it vibrate, which makes a sound. Sound waves bounce up from inside the box towards a receiver, in this case your ear. When you shake the jam jar the dried beans hit the side of the jar and send vibrations through it, we hear this as a rattling sound.

Amplifying the vibrations can increase the volume of sound. The hollow box helps to amplify the sound, due to the sound echoing around the box. Putting a cloth inside the box will block the path of the sound waves making the sound much quieter. The same happens when you wrap a cloth around the jam jar. Plucking the elastic band harder, or shaking the jam jar harder, will cause bigger vibrations and therefore the sound we hear is louder.

Putting the cardboard bridge between the elastic bands and the box allows the elastic band to vibrate without touching the box as much, and therefore should make the sound last for longer. Different sized elastic bands should cause different sounds. Thicker elastic bands vibrate more slowly and therefore make deeper sounds. Thinner bands will vibrate faster and the sound they produce are of a higher pitch.

Explaining it to children

When things move they can make a sound. The sound travels through the air to your ear as sound waves. If you have a slinky these are a really good visual way to represent sound waves. Hold the slinky slightly stretched out with you at one end and your child holding on to the other. Push towards the slinky and the movement should travel from your side of the slinky to the end that your child is holding on to. You ear is cleverly design to be able to receive sounds well, and so when these sound waves are made and travel through the air your ear can easily detect them.

Experiment based on an activity from the fantastic Scientist Academy by Steve Martin book.