Melting |

	Medium – potential for spilling the water
	~30 minutes for the whole activity
	Cheap (jelly can be used for experiment, then prepared and eaten)

Introduction

Melting is a fascinating concept for young children and they love getting their hands wet with this activity.

An important concept is that something doesn’t have to be cold to melt. Try melting chocolate buttons by rubbing them between your hands. The way to melt something is just to heat it up. Even rocks will melt if you get them hot enough!

What you need

Ice cubes – you can make normal ice cubes or try freezing water in old plastic yoghurt pots or margarine tubs. Try freezing small plastic toys into the ice cubes for extra interest! You could also add different food colouring to the ice cubes.
A bowl of warm water – this might need replenishing if it gets cold during the experiment. I’d advise a towel underneath, or do the activity in the garden
Jelly cubes – I made mine up in an ice cube tray but again you can set the jelly in some little yoghurt pots or other small containers. I normally make it up a bit more concentrated than it says on the packet. Leave it in the fridge overnight to make sure it’s set really well.
Clear plastic bag – if you melt the jelly directly in the water it will work but the jelly mixes with the water. It’s easier to see the melted jelly if it’s in the bag.

The experiment

You can download a ‘melting’ wordsearch here.

Start by melting the ice cubes in warm water. Encourage the children to describe what they’re feeling. What does the ice turn into? It’s amazing how long children can spend playing with melting ice cubes!

Then try jelly. It’s best to do this in a bag as you can then see the melted jelly liquid. Jelly is actually an example of a gel. The water in the jelly is trapped in a network of really long molecules called polymers. These polymers are all tangled together in the jelly. Imagine having loads of pieces of string all tangled together. When you heat up the jelly, the forces (we call them bonds) holding the jelly molecules together are broken. The really long molecules can move around freely and so the water is no longer trapped.

Going further

With older children, they could time how long it takes for ice cubes to melt in cool, warm or hot water.

The ice cubes will melt fastest in hot water. The difference in temperature is biggest between the ice cube and the hot water. Energy flows most quickly from the hot water to the ice cube.