How to make light by crushing sugar

Chemical reactions may give out both visible and invisible light (usually heat). Burning a match emits both light and heat, whereas the reaction in glow sticks, for example, gives out mostly visible light. There are even materials that give out light when they are stretched, scratched or crushed.

Sugar, for example, is triboluminescent. In the past, sugar was supplied in cone shaped blocks known as ‘loaves’ that had to be broken up before use. If the room where this took place was sufficiently dark, faint flashes of light could be seen as pieces were chipped off the block.

Try it yourself using a quick experiment for home or school to demonstrate triboluminescence.