These whistling tubes or 'noise-makers' will keep children entertained for hours, whilst also demonstrating the fascinating physics behind music.
Simply twirl the red tube around and the air moving through it produces a range of tones, loosely on the harmonic scale. When you twirl faster a higher tone is produced.
When twirling the Wind Whistler the air molecules within the tube begin to bump together, they vibrate and produce sound waves.
This very simple item, believe it or not, beautifully demonstrates 'Bernoulli's Principle' - that fast moving air molecules create lower pressure.
The idea is that the far end of the hose is moving much faster than the end being held so the higher pressure at the held end effectively sucks up air which in turn creates the whistle.