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Science and Technology K–6 · Year 3

Melting race: which surface melts an ice cube fastest?

Science understanding: Chemical sciences

PracticalLow risk

The idea

Ice melts when heat energy flows into it, and the surface it sits on controls how fast that heat arrives, so a metal tray melts a cube far faster than a foam plate.

What you need

  • 4 ice cubes of the same size from one tray (about 20 g each), weighed
  • 4 surfaces at room temperature: aluminium baking tray, ceramic plate, wooden board, foam plate
  • timer
  • kitchen balance
  • paper towels, weighed dry

How to do it

  1. Weigh each ice cube and write the mass beside its surface.
  2. Predict the order in which the cubes will finish melting and give a reason.
  3. Place one cube on each surface at the same moment and start the timer.
  4. Every 2 minutes record which cubes still have ice. Record the finishing time for each.
  5. As soon as each cube has gone, soak up its melt water with a paper towel that was weighed dry, weigh it again, and compare the gain with the cube's starting mass.
  6. Rank the surfaces and compare the class results; discuss what was and was not kept the same.

What you should see

The cube on the aluminium tray finishes first, the ceramic next, then wood, and the foam plate last. The order follows thermal conductivity: aluminium about 200, ceramic about 1 to 2, wood about 0.15, polystyrene foam about 0.03 W per metre kelvin. The melt water weighs close to what the cube did, which shows melting changes state but not the amount of substance. Any shortfall is water left on the surface or not taken up by the towel, not evaporation: melt water near 0 degrees Celsius is colder than the dew point of ordinary classroom air (about 11 degrees Celsius at 22 degrees and 50 percent humidity), so water vapour condenses onto it rather than leaving it. The ratio of slowest to fastest time is the learner's measured result.

What changes

What you change
surface material
What you measure
time for the cube to melt completely
What you keep the same
  • cube mass
  • room temperature
  • starting temperature of surfaces
  • no sun or draught

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

  • Metal is cold, so ice should melt slowest on it.
  • The ice melts because the room is hot (it melts on any surface above 0 degrees Celsius; the surface sets the rate).
  • Foam keeps the ice warm (it slows heat flow in both directions).

Safety card

Low riskLearners carry it out

Hazards

  • slippery melt water

Controls

  • work on a tray
  • wipe spills at once

Note

Risk assessment before the lesson using Primary RiskAssess or the school's own template.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

  • Science and Technology K-6 Syllabus (2017), current, taught until 2026; code read from the syllabus document on 22 September 2026ST2-6MW-SST2-1WS-S
  • Science and Technology K-6 Syllabus (2024), implemented from 2027; NESA's timeline is 2026 plan and prepare and 2027 start teaching, and schools may choose to implement it during 2026; code read from the outcomes page on 22 September 2026ST2-PQU-01ST2-DAT-01
  • Australian Curriculum v9AC9S3U04AC9S3U03AC9S3I02AC9S3I05

Sources

The pages the author read to write this activity.

  1. www.scootle.edu.au/ec/search?accContentId=AC9S3U04
  2. curriculum.nsw.edu.au/learning-areas/science/science-and-technology-k-6-2024/outcomes
  3. www.nsw.gov.au/education-and-training/nesa/curriculum/science/science-and-technology-k-6-2017
  4. primaryconnections.org.au/v84-sequences/melting-moments
  5. primaryconnections.org.au/teaching-sequences/year-3/making-sense-changes

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