Year 7 Science · Unit 4 · Lesson 16
Extension · Master Worksheet
Learning Goals
Extension · optional
The planet-by-planet detail, out to Uranus and Neptune, goes further than Year 7 asks for and is not assessed. One idea does count, so do not skip it: Pluto being reclassified is exactly the kind of evidence-changes-the-model story this unit tests.
1. Pluto is no longer a full planet. List every condition a world has to meet to count as one.
Odd one out
Each row has a rule. Circle the one item that does not fit the rule, then say why.
| Rule | Group | Odd one out, and why |
|---|---|---|
| An inner, rocky planet | Mercury · Mars · Uranus · Venus | |
| One of the four giant planets | Saturn · Pluto · Jupiter · Neptune | |
| A feature of one of the outer planets | the Great Red Spot · rings of ice and rock · the tallest known volcano · spinning on its side |
Find the error
Jordan’s planet fact file has exactly three wrong statements. Leave the correct ones blank. For each wrong one, rewrite it correctly.
| Jordan’s statement | Correct version (only if wrong) |
|---|---|
| A. Mercury is the hottest planet because it is the closest to the Sun. | |
| B. Uranus has a pale blue-green colour and spins on its side. | |
| C. More than a thousand Earths could fit inside Jupiter. | |
| D. Saturn is the windiest planet and the farthest from the Sun. | |
| E. Pluto became a dwarf planet in 2006 because it had shrunk. |
2. Astronomers study a newly found world far beyond Neptune. It orbits the Sun, it is round, and it shares its region with many other icy bodies. Decide whether it is a planet or a dwarf planet, and justify your decision using all three tests.
Read the data: how long is a year?
Scenario: a year on each planet
Each planet takes its own time to complete one lap, and that time is its year. How does the lap time change as we move outwards?
| Planet | Average distance from the Sun (million km) | Time for one orbit (Earth years) |
|---|---|---|
| Mercury | 58 | 0.24 |
| Venus | 108 | 0.62 |
| Earth | 150 | 1 |
| Mars | 228 | 1.9 |
| Jupiter | 778 | 12 |
| Saturn | 1 430 | 29.5 |
| Uranus | 2 870 | 84 |
| Neptune | 4 500 | 165 |
Source: rounded standard values (the lesson gives no distances or orbit times).
3. A Year 7 student is 12 Earth years old. How old are they in Mercury years?
Age on Mercury Mercury years
4. Describe the pattern in Table 1. Then use Earth and Neptune to show whether the year grows at the same rate as the distance.
5. Pluto’s average distance from the Sun is about 5 900 million km (a rounded standard value). Predict whether a Pluto year is longer or shorter than 165 Earth years, and explain your prediction using the pattern.
6. Evaluate this claim: “Changing Pluto from a planet to a dwarf planet shows that scientists got it wrong, so we cannot trust science.”
Question 1
It orbits the Sun (1); it is round (1); it has cleared its path of other large objects (1). [3 marks]
Odd one out
1 each: Uranus (an outer giant of gas and ice); Pluto (a small dwarf planet, not a giant); the tallest known volcano (Mars, an inner planet). [3 marks]
Find the error
B and C are correct. A: Venus is hottest; its thick clouds trap heat (1). D: Neptune is the windiest and the farthest (1). E: Pluto did not shrink; the rule changed and Pluto has not cleared its path (1). [3 marks]
Question 2
A dwarf planet (1). It orbits the Sun and is round (1), but it shares its region with many icy bodies, so it has not cleared its path (1). [3 marks]
Read the data: Question 3
12 ÷ 0.24 (1) = 50 Mercury years (1). [2 marks]
Question 4
Farther from the Sun, longer year (1). Neptune is 4 500 ÷ 150 = 30 times farther than Earth (1) but its year is 165 times longer: the year grows faster (1). [3 marks]
Question 5
Longer (1): Pluto is farther out than Neptune (5 900 vs 4 500 million km), and farther planets take longer to orbit (1). [2 marks]
Question 6
Marking guide: 1 judgement: disagree; 1 new evidence: Pluto is small, one of many similar icy worlds beyond Neptune; 1 Pluto did not change, the definition did (2006); 1 Pluto orbits and is round but has not cleared its path; 1 otherwise the planet list would keep growing; 1 updating ideas with evidence is a strength of science. [6 marks]
Model answer: I disagree. Pluto did not change; the evidence did. Better telescopes showed it is one of many similar icy worlds beyond Neptune, so the planet list would keep growing. In 2006 astronomers agreed a clearer rule: Pluto orbits the Sun and is round but has not cleared its path, so it is a dwarf planet. Updating ideas to fit evidence makes science more trustworthy, not less.
Common error: Q4, subtracting instead of dividing.