What it shows
Water expands a little when it freezes. Ice takes up more space than the same water, which is why ice floats.
The science
When water freezes, its particles arrange into an open pattern with gaps. This makes ice take about nine percent more space. Because ice is less dense than water, it floats. This is why pipes can burst in very cold places and why lakes freeze from the top.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- A small plastic bottle or a tall plastic cup
- Water
- A marker
- A freezer
- A ruler
Safety
For this project: Never use glass, as it can crack. An adult must help with the freezer. Leave room at the top of the bottle.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Fill the plastic cup with water about three quarters full.
Mark the water level on the outside with a marker.
Measure the height of the water with a ruler and write it.
Place the cup in the freezer for the night, standing upright.
Take it out in the morning and look at the ice level.
Mark the new level and measure the height.
Compare the two heights and say which is higher.
Place a piece of ice in water and watch it float.
What you should see
The ice stands a little higher than the water did, and the ice cube floats in water.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1What happened to the level when water froze?
It went up.
2Why does ice float?
It is lighter than the same amount of water.
3Why not use a glass?
The expanding ice could break it.
4Why can this burst pipes?
Freezing water expands and pushes on them.
Take it further
Freeze a small amount of milk and juice and see if they act the same.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
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