These whistling tubes or 'noise-makers' will keep children entertained for hours, whilst also demonstrating the fascinating physics behind music.

To play, simply twirl the red tube around in the air. The air moving through the instrument produces a range of tones, loosely on the harmonic scale. When twirling the Wind Whistler, the air molecules within the tube begin to bump together and these vibrations produce sound waves. When you twirl faster, a higher tone is produced.

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.