Year 7 Science · Unit 4 · Lesson 2
Master Worksheet
Learning Goals
1. Define peer review and replication, and state one way they are different.
Find the error
Sam’s summary of the lesson
Line 1: A hypothesis becomes a theory, and a theory becomes a law once it has been tested enough.
Line 2: Peer review means other scientists repeat the experiment in their own labs.
Line 3: Scientists publish their results so that others can learn from them, check them and extend them.
Line 4: A result that other teams cannot repeat should still be trusted if the scientist who found it is famous.
2. Three of Sam’s four lines contain one error each. Name each wrong line and rewrite it so that it is correct.
3. Big achievements, such as vaccines that protect millions of people, are built by huge international teams. Give two reasons why such a team can achieve more than one scientist working alone.
Read the data: the Brain-Boost bar
Scenario
In a first study, Lab A gave 10 students a “Brain-Boost” snack bar and 10 students a plain bar before a memory test. The Brain-Boost group scored 15% higher. Three other labs then repeated the study, each with many more students.
| Lab | Students tested | Change in score (%) |
|---|---|---|
| A (first study) | 20 | +15 |
| B | 200 | +1 |
| C | 150 | 0 |
| D | 180 | −1 |
Source: made-up results for this worksheet.
4. Calculate the average change in score for the three repeat labs (B, C and D).
Average change %
5. Did the repeat labs replicate Lab A’s result? Use Table 1 to say what scientists should now conclude about the idea that the bar improves memory.
6. The company still advertises: “Proven by scientists: 15% better memory!” Explain why this advert is misleading.
7. Evaluate this claim: “Great discoveries are made by lone geniuses. Teamwork and checking just slow science down.”
Question 1
Peer review: experts check the work for mistakes before it is shared; replication: others repeat the experiment to see if they get the same result (1). Peer review checks the report; replication redoes the experiment (1). [2 marks]
Find the error
2. Line 1: a theory never turns into a law; a law describes what happens, a theory explains why (1). Line 2: that is replication; peer review is experts checking for mistakes (1). Line 4: a result others cannot repeat should be doubted, whoever found it (1). Line 3 is correct. [3 marks]
Question 3
Any two, 1 mark each: different skills; the work is shared out; each group builds on the others’ results; members check each other’s work. [2 marks]
Question 4
(1 + 0 − 1) ÷ 3 (1) = 0% (1). [2 marks]
Question 5
No: B, C and D found almost no change (average 0%), not +15% (1). Three larger repeat studies agree, so they outweigh one small first study that may have been luck (1). The idea is not supported and should be dropped or changed (1). [3 marks]
Question 6
It quotes only the one study that others could not replicate (1) and ignores the repeated evidence showing no real change, so it is not “proven” (1). [2 marks]
Question 7
Marking guide: 1 judgement: the claim is wrong; 1 research is usually collaborative, with teams sharing skills and results; 1 example: CSIRO teams took years to develop fast wireless internet; 1 builds on earlier work (Murriyang used earlier ideas about radio waves); 1 checking catches mistakes: Table 1’s first result failed replication; 1 Marshall and Warren were trusted only after labs worldwide repeated their work. [6 marks]
Model answer: The claim is wrong. Research is usually collaborative: CSIRO teams worked for years on fast wireless internet, and Murriyang was built on earlier ideas about radio waves. Checking catches mistakes: in Table 1, Lab A’s 15% vanished when three labs repeated it. Even Marshall and Warren were only trusted after labs worldwide repeated their work.
Common error: trusting a single exciting result over several repeat studies that agree.