Two cups can end at the same temperature even when one cools more than the other. Calculate each temperature drop by subtracting the final temperature from its own starting temperature. Then check whether both cups started under the same conditions before judging which wrapping kept the water warmer.
The MOE primary science syllabus connects temperature changes with heat gained or lost, and the SEAB PSLE Science syllabus assesses how pupils interpret information and explain their reasoning. This guide separates a calculation from a conclusion about what caused the difference.
- Read the start and finish values for each cup.
- Subtract the final value from that cup’s own starting value.
- Use the data to describe what happened in the test.
- For a fair comparison of wrappings, keep the starting temperatures and other conditions the same.
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Answer the question the table can support
‘Which cup ended warmer?’ asks you to compare the final readings. ‘Which cup cooled more?’ asks you to compare the drops. ‘Which wrapping keeps water warmer?’ asks for a conclusion about the wrapping. For that last question, check how the test was set up.
Water warmer than its surroundings transfers heat to them. A cup that starts hotter has a larger initial temperature difference from the room, assuming the same surroundings. That difference can affect cooling. The starting temperature matters even if both cups are left out for the same time.
Write a drop in degrees Celsius. ‘A’s temperature fell by 18 °C’ tells the reader what was measured. If the question asks for the reason, add how the setup or the path of heat transfer affects the result.
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Worked example | Equal final readings
Two pupils use identical cups and equal amounts of water. They wrap the cups with different materials and measure the temperature after ten minutes. The table uses invented measurements for practice.
| Cup | Starting temperature | Final temperature | Temperature drop |
|---|---|---|---|
| A | 72 °C | 54 °C | 18 °C |
| B | 64 °C | 54 °C | 10 °C |
Both cups finished at 54 °C. Cup A’s temperature fell by 18 °C, while Cup B’s fell by 10 °C. So the temperature drop was 8 °C larger in Cup A in this trial.
A suitable answer to ‘Can we conclude that B’s wrapping keeps the water warmer?’ is ‘The starting temperatures were different. The difference in cooling could be affected by both the starting temperature and the wrapping. Start both cups at the same temperature to compare the wrappings fairly.’
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Practise with a fairer comparison
For a second test, imagine both cups start at 65 °C. Use identical cups, the same amount of water, the same kind of lid or no lid on both, and the same location and ten-minute interval. If comparing wrapping materials, also match the thickness and coverage of the wrapping where possible.
Suppose Cup A now finishes at 52 °C and Cup B finishes at 57 °C. A drops by 13 °C and B drops by 8 °C. The water in B stayed warmer in this test. The results support the conclusion that B’s wrapping reduced heat loss more effectively under the tested conditions.
If a question asks how to strengthen the evidence, suggest repeating the fair comparison and looking for a similar pattern. If it asks how to fix the first test, identify the unequal starting temperatures and say how to make them equal.
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Frequently asked questions
Can two cups finish at different temperatures after the same drop?
Yes. If both drop by 10 °C but start at 70 °C and 60 °C, they finish at 60 °C and 50 °C respectively.
Why keep the amount of water the same?
The amount of water can affect how much its temperature changes. Matching the amounts helps isolate the effect of the wrapping.
What should I circle when I read the table?
Circle each start and finish reading in the same row. After finding the drops, circle any conditions that differ between the cups before writing a conclusion.
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Sources and next reading
SEAB PSLE Science examination syllabus, applicable from 2026