On the afternoon of 23rd May, Alexandra Ballard, Head of Science at St Mary's Calne, delivered a science assembly at
St Margaret’s Preparatory School for all the children in Years 1-6. The assembly focused on two questions: ‘What is sound?’ and ‘How do humans make sounds?’.

Starting with the ideas of Ancient Greek philosophers, Aristotle and Democritus, the children were shown how scientists worked out that sound was a wave. Sound waves were shown on a cathode-ray oscilloscope (CRO) and, as the highlight of the assembly, using a Rubens' tube* where lots of little flames move to make the shape of the sound wave passing through.  The children were easily able to see that increasing the pitch of the sound increased the number of waves and increasing the loudness of the sound made the wave peaks higher. They even got the flames to dance along to Ice Ice Baby! 

The assembly then moved on to focus on how the human voice box works, using a violin to demonstrate the principle, before showing the children how vocal cords can change shape using an endoscope. The pupils very much enjoyed this brief introduction and were full of interesting questions at the end.  The children were also asked to think of some science questions to write down for science students at St Mary's Calne, who will answer the questions after Half Term for the pupils at St Margaret's.   

The assembly ended with the children enthusiastically singing The Trees of the Field (will clap their hands) and watching the effect of their singing on the flames of the Rubens' tube!

*A Rubens' tube, also known as a standing wave flame tube, is an antique physics apparatus for demonstrating acoustic standing waves in a tube. Invented by German physicist Heinrich Rubens in 1905, it graphically shows the relationship between sound waves and sound pressure.