When you have been teaching the topic of ‘Sound’ for more years than you care to remember, it’s great to come across something new that you haven’t tried before. That’s what happened recently, as I was trawling through the Internet – I happened upon something called a ‘tonoscope’.
Demonstrating vibrations can sometimes be rather dull. There are the old favourites, of course – tuning forks in water; rice on a drum; striking a ruler on the desk; feeling your voice box as you speak – all of which do the job but are not particularly exciting.
A tonoscope on the other hand, generates a bit of magic. It is an acoustic device that enables you to create intricate patterns by just using the sound of your voice.
It is actually quite easy to make. You just need a length of 4” PVC drainpipe (which you will need to cut to an appropriate size) and an angled elbow piece – both of which I found in B&Q.
Below is a link to the instructional video I followed:
The most challenging part was trying to stretch the balloon over the upright end of the elbow piece. This proved very difficult – even with two of us trying – and we split a couple of balloons straight away.
Time for some creative thinking. Fortunately, because we are now used to ‘thinking like engineers’, we have become quite resilient and adept at problem solving. The issue was trying to keep the balloon on the pipe once we had stretched it across. Before we had time to put an elastic band around, one side invariably popped off – very frustrating.
It was Mrs Yates, the Year 4&5 TA, who came up with the solution. Before attempting to attach the balloon, she fixed a strip of double-sided tape around the edge of the pipe. Brilliant! It worked first time. The balloon stuck to the tape and allowed time for the elastic bands to be placed around the edge.
The results were not disappointing. We poured some salt onto the surface of the balloon and encouraged the children to speak into the tube. It was a great way to make sound waves visible.
What was more impressive was the questions that the children were asking:
- What happens if you put the tonoscope on different surfaces? Will the sound change?
- What is the difference in pattern between high and low sounds?
- How loud do we have to shout to bounce the salt off the balloon?
- Will it work with sugar or sand?
- Will too much salt stop the balloon from vibrating?
Sometimes when you try out an idea, it falls flat. Not this one. It was really good fun. The children even asked if they could take it into assembly to show the rest of the school.