Squeeze the bottle and enjoy watching the sachet floating and sinking.
Ingredients and equipment that you will need
You need a sachet of sauce (from a cafe or fish and chip shop)
Or.. a pen top plus plasticene… or blutac. *see below
An old plastic bottle, ideally two litre size
Method and further information
Drop the sachet in the bottle, fill to the top with water. Screw the lid on tight.
You should find that when you squeeze the bottle, the sachet sinks. When you let go, it rises again.
Squeezing the bottle increases the pressure on the sachet, making it smaller and denser, so it sinks.
If your sachet doesn’t sink clip a paperclip to it to make it heavier.
*A sauce sachet works because it has a bubble of air inside. You can make this air bubble with a pen top plugged with plasticene or blutac. You might need to experiment with more or less plasticene to make it float.
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.