What it shows
Insulators slow the flow of heat into an ice cube, so it melts more slowly. By wrapping equal cubes in different household materials and weighing the meltwater, you find which ones insulate best.
The science
Heat from the warm room flows into the ice and melts it. Materials that trap air, like wool and paper, are poor conductors and slow the flow of heat. Foil is a metal and conducts heat well, but when tightly wrapped it also reflects some warmth, so its result may surprise you.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- 5 equal ice cubes from one tray
- Aluminium foil, woollen cloth, newspaper and cotton cloth
- Five small cups or bowls
- A measuring spoon or a small cup for meltwater
- A clock or timer
- Rubber bands
- A marker
Safety
For this project: Do not eat the ice. Wipe up water to prevent slips, and wash hands after handling the wraps.
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
7 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.
Take five ice cubes out of the freezer at the same time and place each in its own cup.
Wrap one in foil, one in wool, one in newspaper and one in cotton, tied with a rubber band, and leave one unwrapped.
Write the name of the wrap on each cup.
Place all five cups in the same shady spot.
After one hour open each wrap and measure the water that has melted, using the measuring spoon.
Check again after two hours and three hours.
Rank the wraps from best to worst insulator and draw a bar chart.
What you should see
The wool and newspaper wraps keep the most ice for the longest time, while the unwrapped cube melts first. The bar chart ranks the materials as insulators.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1What is an insulator?
A material that does not let heat pass through easily.
2Why is wool a good insulator?
It traps air, which is a poor conductor.
3Why have an unwrapped cube?
As a control to compare with.
4Name a use of insulation at home.
A flask or an icebox.
Take it further
Test a double wrap of newspaper and a loose wrap to see how trapped air changes things.
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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