If you’ve seen me do the three cup trick, this is how it’s done.
Ingredients and equipment that you will need
Sodium polyacrylate crystals
A paper or plastic disposable cup (so that you can put the whole thing in the dustbin afterwards)
Method and further information
You can get sodium polyacrylate from the garden centre (Swelgel or Plant gel) or from babies nappies – cut the nappy up over a piece of newspaper and the crystals will drop onto the paper. DO NOT dispose of this down the sink, toilet or drain! Put it in the dustbin.
Crystals of sodium polyacrylate absorb masses of water. Put a few crystals of sodium polyacrylate in the cup and slowly add water. You can colour the water with food colouring if you like. Watch as the crystals expand.
Be careful – you should ask an adult to help you with these experiments. Do your experiments in old yoghurt pots, jam jars or bottle tops. Don’t use cups or glasses in case someone thinks it’s a drink.