Investigate how liquids freeze and melt by making delicious ice lollies.
Early Learning Goal links
- Understanding the World ELG: Past and Present
- Understanding the World ELG: People, Culture and Communities
- Understanding the World ELG: The Natural World
- Expressive Arts and Design ELG: Creating with Materials
STEM vocabulary to introduce
Water, wet, liquid, flowing, pour, fill, freezing, shape, colour, cold, solid, hard, melting, dripping, smooth, shiny
Before you start
Show the children the glaciologist poster and tell the children that they are going to be glaciologists for this activity.
Ask the children if they know what a glaciologist does. A glaciologist is a scientist who studies glaciers. Glaciers are huge lump of ice found in mountains or near the poles which move slowly towards the sea.
Tell the children of the attributes. Glaciologists are:
Curious: glaciologists want to know more about how the ice in glaciers is made.
Observant: glaciologists look at the ice carefully to see what colour and shape it is.
Resilient: glaciologists need to be able work in cold and windy conditions. They need to be quick to recover and get back out in the cold again each day.
Explain that today they will be curious and observant in their glaciologist task. They are going to learn how to make ice lollies.
What to do
Step 1
Give each child a cup of juice, a pipette and an ice lolly mould. Model how to use the pipette. Ask the glaciologists to fill the mould with juice using the pipette. This is more accurate than pouring and gives you chance to discuss the process with the glaciologists while they are working. It also develops fine motor skills!
You could ask:
- How will we turn our juice into ice lollies?
- Where should we do that?
- How long will it take?
- What shape will your ice lolly be when it is ready?
- What colour will it be?
- What do you think it will feel like?
Step 2
If you are using a DIY lolly mould, cover it with foil and push a lolly stick through the top of the soil into the liquid. You might want to label the lollies with the children’s names. Put the lollies into the freezer overnight.
Step 3
When they are frozen, give the glaciologists their lollies.
While they are eating them, you could ask:
- What shape is your ice lolly?
- What colour is it?
- (If you have a stick) How does the stick stay in?
- Do you think all juice would freeze to make an ice lolly?
- Is you ice lolly melting? Why?
Other things to try
Investigate making ice lollies using:
- Fizzy water or pop
- Fruit puree
- Smoothie
- Yoghurt
- Milk
What happens if you add:
- Chopped fruit?
- Sprinkles?
- Chocolate chips?
Making stripy ice lollies:
- Add layers of different liquids
- You will need to freeze each layer before you add the next one.
The science of freezing and melting
We have put together some useful information about the science of freezing and melting to accompany this activity. Don’t worry this is for your information only and to help you answer any questions children may have. We don’t expect you to explain this to the children in your setting!
How does water freeze?
The molecules in water are constantly moving. In a liquid, the molecules move more, and faster, than in a solid. As the liquid cools down the molecule movement slows down. When the water temperature reaches around 0°C, the molecules are closer together and weak bonds form between them. They form a solid that we call ice.
Why does ice melt?
When ice is heated, the molecules which are held together by weak bonds, start to vibrate more vigorously. As the temperature of the water rises above 0°C the movement of the molecules is enough to break the bonds between them and liquid water forms.
Do all liquids freeze?
No, not all liquids will freeze.
When liquids begin to freeze, a tiny ice crystal forms first. This ice crystal then grows as other particles in the liquid attach themselves to the ice crystal. Different liquids freeze at different temperatures. Water freezes faster than liquids with salt or sugar in them. Liquids with a higher viscosity (thick and sticky in consistency, such as honey or washing up liquid) freeze more slowly than less viscous liquids and some will not freeze at all.
What you’ll need
- Ice lolly moulds or ice pop bags or
- DIY ice lolly moulds such as ice cube trays or disposable cups or yoghurt pots
- For DIY moulds you will need: lolly pop sticks and foil
- Sugar free cordial made up with water as instructed on the bottle or pure fruit juice in a cup for each child- check for any allergies.
- Pipettes
- A freezer
- The glaciologist poster
Duration
- 10 minutes or so to make the ice lollies
- Freezing time
- 5 to 10 minutes to discuss and eat the lollies the next day
