To compare evidence across a mixed task, state the pattern in each dataset with numbers, say where they agree and differ, then say what the data cannot show. The skill is a short, structured paragraph, not a long one.
This page supports the investigation evaluation module and sits inside the Co-ordinated Sciences learning guide.
What is actually going wrong?
Mixed tasks often hand you two tables from two contexts, for example a living system and a chemical reaction. Three habits cause lost marks:
- Two separate summaries. The answer describes table A, then table B, and never links them.
- Words without numbers. “It goes up” replaces “from 14 to 31”.
- A claim bigger than the data. Three readings become “always”.
A four-step comparison method
- Read each table once and write the pattern with two numbers from it.
- Line the patterns up. Is the direction the same? Is the size of change similar?
- Explain any difference using the science, only if the question asks why.
- State a limit. Name one thing the data cannot show and one reading that would help.
Worked example
A student investigates whether warming speeds things up. There are two sets of results, each from one run.
Set A, an enzyme (catalase) in liver, oxygen bubbles in one minute:
| Temperature (°C) | 20 | 40 | 60 |
|---|---|---|---|
| Bubbles | 14 | 31 | 2 |
Set B, magnesium ribbon in dilute acid, time until the ribbon disappears:
| Temperature (°C) | 20 | 40 | 60 |
|---|---|---|---|
| Time (s) | 120 | 52 | 24 |
Step 1, patterns. In A, bubbles rise from 14 to 31 between 20 °C and 40 °C, then fall to 2 at 60 °C. In B, the time falls from 120 s to 52 s to 24 s, so the reaction gets faster each time.
Step 2, line up. Both sets speed up from 20 °C to 40 °C. In B, 120 ÷ 52 is about 2.3, so the reaction is about 2.3 times faster. In A, 31 ÷ 14 is about 2.2 times more bubbles. Between 40 °C and 60 °C the two sets split.
Step 3, explain. Particles move faster when warmer, so collisions are more frequent and more energetic, which fits B and the first half of A. An enzyme is a protein whose shape can be damaged by heat, which fits the collapse at 60 °C in A.
Step 4, limit. Each result is one run at three temperatures. We cannot say where A peaks, and the data does not show the exact temperature at which the enzyme is damaged.
Answer: “Warming speeds up both the enzyme and the magnesium reaction from 20 °C to 40 °C, by about 2.2 and 2.3 times. At 60 °C the magnesium reaction keeps speeding up, while the enzyme result falls to 2 bubbles, which is consistent with heat damaging the enzyme. Only three temperatures were used, so the peak for the enzyme is unknown.”
The mistake to watch for
Mistaken answer: “Both show that higher temperature means faster reactions, because in A the bubbles go up and in B the time goes down.”
The student ignored the 60 °C result in A, which contradicts the claim.
The correction is to read every point. A result that breaks the pattern is usually the point the question wants you to explain.
Check yourself
1. Table A shows 14 bubbles at 20 °C and 31 at 40 °C. Write the pattern with two numbers.
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"Bubbles increased from 14 to 31 when the temperature rose from 20 °C to 40 °C."2. A student says “the enzyme always works fastest at 40 °C”. What is wrong?
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Only three temperatures were tested, so 40 °C gave the highest reading of those three, which does not show it is the peak overall. A reading at 30 °C or 50 °C might be higher.3. Name one improvement that links to a real limitation in the example.
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Test more temperatures between 20 °C and 60 °C and repeat each one. This addresses the limit that the peak is unknown and each result comes from a single run.What can you do next?
Use the scientific investigation critic with your own description and data. Then read what a dataset can and cannot establish for the wording of a safe claim.
If the method is clear but your written comparisons still wander, a teacher in online one-to-one Co-ordinated Sciences tuition can work through your paragraphs with you, starting with a paid one-hour trial.