Year 7 Science · Unit 4 · Lesson 2
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Learning Goals
1. When a team publishes its results, other scientists can use them in three ways. Name two of them.
What does it show?
Decide what each example shows: collaboration, replication, peer review, or building on earlier work. A word can be used more than once.
| Example | What it shows |
|---|---|
| (a) Engineers use earlier discoveries about radio waves to design a new telescope. | |
| (b) A team in Canada repeats an Australian experiment to see if it gets the same result. | |
| (c) Astronomers from many countries share one telescope and pool their results. | |
| (d) Two experts read a report and send back its mistakes before it is published. | |
| (e) Biologists and chemists work side by side in one team to study coral. |
Order the steps: from a strange signal to trusted knowledge
A team using a radio telescope finds something new. Number the stages from 1 (first) to 6 (last).
| Step | Stage |
|---|---|
| The team tests its idea, then writes up its method and results. | |
| After years of repeated testing, the explanation is accepted as reliable knowledge. | |
| The team notices a faint radio signal from deep space that repeats in a regular pattern. | |
| Teams in other countries use their own telescopes, repeat the observations and get the same result. | |
| The team suggests a hypothesis to explain what could be sending the signal. | |
| Fellow experts check the report for mistakes before it is published. |
2. “Objects always fall towards the Earth when they are dropped.” Is this a scientific law or a scientific theory? Explain how you decided.
Read the data: the mould-proof coating
Scenario
Team Kestrel reports that a new food-safe coating keeps bread free of mould for longer. Four other labs repeat the experiment with the same kind of bread, kept in the same conditions. Each lab records how many days pass before mould appears.
| Lab | Coated bread (days) | Uncoated bread (days) |
|---|---|---|
| Team Kestrel (first study) | 10 | 4 |
| Lab 2 | 9 | 4 |
| Lab 3 | 5 | 4 |
| Lab 4 | 10 | 5 |
| Lab 5 | 4 | 4 |
Source: made-up results for this worksheet.
3. In how many of the four repeat labs did the coated bread last at least 3 days longer than the uncoated bread? Name them.
4. Is the coating idea trusted knowledge yet? Explain using the word replication, and describe two things the scientists should do next.
5. Evaluate this statement: “Once a scientific theory is accepted, it can never be changed.” Use an example from astronomy in your answer.
Question 1
Any two, 1 mark each: learn from it; check it by repeating it; extend it by asking a new question it made possible. [2 marks]
What does it show?
(a) building on earlier work; (b) replication; (c) collaboration; (d) peer review; (e) collaboration. All five = 3; three or four = 2; one or two = 1. [3 marks]
Order the steps: from a strange signal to trusted knowledge
Reading down the table as printed, the correct step numbers are 3, 6, 1, 5, 2, 4. In order: notice the repeating signal; suggest a hypothesis; test it and write it up; peer review before publishing; other teams replicate; accepted after years of repeated testing.
Question 2
A scientific law (1). It describes a pattern seen again and again (what happens); it does not explain why objects fall, which is what a theory does (1). [2 marks]
Question 3
Two labs (1): Lab 2 (9 vs 4 days) and Lab 4 (10 vs 5 days) (1). [2 marks]
Question 4
Not yet: only two of four labs replicated it; Labs 3 and 5 found little or no difference (1). Any two next steps (1 each): compare the labs’ methods; have experts peer review them; ask more labs to repeat the test. [3 marks]
Question 5
Marking guide: 1 judgement: the statement is wrong; 1 an accepted theory is well tested and backed by lots of evidence, so it is very trustworthy; 1 but it is still open to checking; 1 if careful new evidence disagrees, scientists look again and update or replace it; 1 example: new observations from Murriyang at Parkes and space telescopes improve explanations of stars and galaxies; 1 changes build on earlier work, so changing is a strength, not a weakness. [6 marks]
Model answer: The statement is wrong. An accepted theory is well tested and backed by lots of evidence, so it is very trustworthy, but it is still open to checking. If careful new evidence disagrees, scientists update it or replace it. Murriyang at Parkes and space telescopes keep giving fresh observations that improve explanations of stars and galaxies. Each change builds on earlier work, which is a strength of science.
Common error: ranking a law as “a theory with more evidence”; a law describes, a theory explains, and a theory never turns into a law.