To evaluate a claim, restate it in your own measurable words, match it to the data, then say what the data cannot cover. A conclusion that fits the evidence earns more marks than a confident one.
This lesson closes the four-lesson set on materials and technology through practical evidence. The same skill is used for classroom data in evaluating a science claim from a supplied dataset.
What is the restate, match, limit routine?
- Restate: say what the claim means in a measurable form, using your own words.
- Match: find the data that tests that measurable form.
- Limit: say which conditions the data covers and which it does not.
Worked example 1: a drop-test claim
A fictional advert says a phone case called Shieldex “never cracks”. An original table shows the drop-test results for 10 cases on a hard floor.
| Drop height | Cases that survived out of 10 |
|---|---|
| 1.0 m | 10 |
| 1.5 m | 9 |
| 2.0 m | 6 |
Restate. The claim means that a Shieldex case survives every drop. Measured, it predicts 10 out of 10 survivors at every height.
Match. At 1.0 m, 10 of 10 survived, which fits the claim. At 1.5 m, 9 of 10 survived, so one case cracked. At 2.0 m, 6 of 10 survived, so 4 cases cracked.
Limit. The test used ten cases, one floor type and three heights. It says nothing about drops onto carpet, soil or from 3 m.
Conclusion. The data does not support “never cracks”. It supports the statement that all 10 survived a 1.0 m drop onto a hard floor in this test, while 4 of 10 cracked at 2.0 m.
Worked example 2: a lightness claim
A fictional advert says a panel is “half the weight of steel”. The table supplies a steel density of 7.8 g/cm³ and a panel density of 3.9 g/cm³.
Restate. The claim means that, for the same volume, the panel has half the mass of steel.
Match. 3.9 ÷ 7.8 = 0.5, so the mass of the panel is half the mass of the same volume of steel. The claim is supported for equal volume.
Limit. The data gives no strength figures. A panel that is half the mass may also be weaker, so the claim does not show that it can replace steel in every use.
The mistake that costs marks
The slip is to repeat the advert. “Shieldex is unbreakable because it never cracks” adds no evidence.
| Wrong | Right |
|---|---|
| “The product is unbreakable, as claimed” | “Four of ten cases cracked at 2.0 m, so the claim is not supported at that height” |
| “The claim is false” | “The claim holds at 1.0 m but not at 2.0 m” |
| “The data proves it is the best” | “The data shows what was tested and nothing further” |
The repair is to write numbers from the table in your answer and to name a condition that was not tested.
Check yourself
A fictional kettle claims “heats faster than any other kettle”. An original test timed two kettles to heat 1 litre of water from 25°C to 100°C: Kettle Z took 180 s and Kettle Y took 210 s. Write a conclusion that fits the evidence.
Answer
Restate: Kettle Z heats water faster than another kettle. Match: Z took 180 s and Y took 210 s, so Z was 30 s faster than Y in this test.
The claim says “any other kettle”, but only one other kettle was tested. The data supports Z being faster than Y, and it does not support the claim about all kettles. Assumption: both kettles started with the same water volume and temperature.
What to study next
Test all four moves together in the integrated practice set. The claim evidence revision desk can help you polish the wording of your conclusions.
For a teacher to go through your conclusions with you, see online one-to-one Science tuition.