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Australian primary science · Year 3 · Lesson 2 of 3
Ice cube race
Inquiry question: Where will an ice cube melt the fastest?
Check practical materials
Fair testing
What students learn
Heat sources such as the Sun and our bodies give off heat. Ice melts when heat moves into it from something warmer. The more heat that moves in, the faster it melts.
Success criteria
- I can name three sources of heat.
- I can keep the test fair by using the same size ice cubes and cups.
- I can explain why one ice cube melted fastest.
Preparation and materials
Before this lesson: Students know heat moves from hotter to cooler things (lesson 1).
- Ice cubes, all the same size — 52 (4 per pair), plus spares
- Plastic cups, all the same — 52 (4 per pair)
- Bowls or large containers — 13
- Warm tap water — Enough to half-fill 13 bowls
- Paper towel — 13 sheets
- Esky or cooler bag to keep ice until the lesson — 1
- Timer (iPad or class clock) — 1 per pair or the class clock
Teacher setup
- Freeze ice the day before in the same trays so cubes are the same size. Keep them in an esky until the lesson.
- Find a sunny spot and a shady spot (on a windowsill or just outside). On a cloudy day, use the warmest spot in the room instead of the sun.
- Half-fill each bowl with warm tap water just before the investigation.
- Print one investigation record per pair.
Safety and adaptations
- Use warm tap water only: no kettles or hot water for students.
- Teacher checks the water feels comfortably warm, not hot, before handing it out.
- Hold ice through the cup, not in bare hands for a long time.
- If the sunny spot is outside, wear hats, put the cup down and come straight back inside. Don’t wait in the sun.
- Wipe up spills straight away so no one slips.
Review your school policies and curriculum requirements before teaching.
How to investigate
The lesson sequence should leave pupils with evidence to interpret, not only an activity to finish.
- Pairs predict which ice cube will melt first and which will melt last.
- Put one ice cube in each cup and start the timer.
- Cup A goes in the sun, cup B in the shade, cup C is held in your hands (take turns), and cup D stands in the bowl of warm tap water.
- At 5 minutes and 15 minutes, look and draw how much ice is left in each cup.
- Rank the cups from most melted to least melted, and compare with your prediction.
Teacher modelling prompt
Show the four cups. Think aloud: “I am comparing melting in different places. Several conditions may differ between places, so this comparison alone cannot tell us exactly which condition caused the difference. Same size ice cube, same cup, same start time. At 5 minutes and at 15 minutes I will look and draw how much ice is left.”
Record and explain evidence
Recording question: Where will an ice cube melt the fastest?
| Cup | Where it was | Ice left after 5 minutes (draw it) | Ice left after 15 minutes (draw it) | Rank (1 = most melted) |
|---|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Who is right? What does the shade cube tell us?
Check understanding
What should pupils know? Name three sources of heat.
Explain with evidence: Why did the ice cube in warm water melt fastest?
Apply the idea: You want your ice block to last longer at the beach. Where should you keep it? Why?
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.