All lessons › Sun, shade and hot surfaces › Lesson 2
Australian primary science · Year 3 · Lesson 2 of 3
Dark or light?
Inquiry question: Does the colour of a surface change how fast sunlight melts an ice cube?
Check practical materials
Fair testing
What students learn
Heat from sunlight moves into things and changes their temperature. A dark surface warms up faster in sunlight than a light or shiny one, so ice on it melts faster.
Success criteria
- I can predict which ice cube will melt first and give a reason.
- I can keep the test fair by changing only the colour of the surface.
- I can explain my results using the words heat and sunlight.
Preparation and materials
Before this lesson: Students know dark playground surfaces get hotter in the sun (lesson 1).
- Ice cubes, all the same size (from the same tray) — 39 (3 per pair), plus spares
- Squares of black paper or card, about 10 cm — 13
- Squares of white paper or card, the same size — 13
- Squares of aluminium foil, shiny side up, the same size — 13
- Trays or large flat plates to stand the squares on — 13
- Esky or cooler bag to keep the ice — 1
- Timer (iPad or class clock) — 1 per pair or the class clock
Teacher setup
- Freeze ice the day before in the same trays; keep it in an esky until the lesson.
- Find a sunny spot outside, or a sunny windowsill. On a cloudy day, use the sunniest windowsill and allow more time.
- Cut the paper and foil squares (scrap paper is fine; black paper can be coloured with a marker).
- Print one investigation record per pair.
Safety and adaptations
- Wear hats if working outside in the sun, and don’t stay out longer than needed.
- Never look straight at 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 last, with a reason.
- Put the three squares on a tray in the same sunny spot.
- Place one ice cube in the middle of each square at the same time and start the timer.
- Every 5 minutes, draw how much ice is left on each square.
- When one cube has fully melted, rank the squares and compare with your prediction.
Teacher modelling prompt
Show the three squares and one ice cube. Think aloud: “I am changing only the colour of the square. Same size ice cube, same spot in the sun, same start time. Every 5 minutes I’ll draw how much ice is left on each square.” Model a quick drawing of a half-melted cube.
Record and explain evidence
Recording question: Does the colour of a surface change how fast sunlight melts an ice cube?
| Square | Ice left after 5 minutes (draw it) | Ice left after 10 minutes (draw it) | Ice left after 15 minutes (draw it) | Rank (1 = melted fastest) |
|---|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Which claim fits what we know about heat sources?
Check understanding
What should pupils know? Where did the heat that melted the ice come from?
Explain with evidence: Why did the ice on the black square melt faster than on the white square?
Apply the idea: You want to keep a drink bottle cool at sport. Should you wrap it in a black or a white cloth? Why?
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.