Year 7 Science · Unit 4 · Lesson 8
Master Worksheet
Learning Goals
Odd one out
The rule: sort by the motion that causes each event (rotation, orbit or tilt). In each row, circle the one event caused by a different motion from the other three, and name the motion that causes the other three.
| Row | Events | Motion for the other three |
|---|---|---|
| A | sunrise · sunset · a leap year · night falling | |
| B | longer summer days · slanted winter sunlight · the Sun setting in the west · opposite seasons in the two hemispheres | |
| C | a 365.25-day year · a birthday coming round again · one lap of the Sun · a 24-hour day |
Find the error
Ravi’s explanation
Line 1: Night happens when the Sun moves behind the Earth.
Line 2: One full rotation of the Earth takes about 365.25 days.
Line 3: A leap year adds one extra day, 29 February, every four years.
Line 4: In June the Southern Hemisphere is tilted toward the Sun, so Australia has summer.
1. Three of Ravi’s four lines contain an error. Name each wrong line and rewrite it correctly.
2. Draw the Sun and the Earth in December, with the Earth’s axis tilted so the Southern Hemisphere leans toward the Sun. Label the Sun, the axis, the Southern Hemisphere and Australia’s season, and draw sunlight arriving.
3. Imagine the Earth spun upright, with its axis not leaning at all. Would we still get summer and winter? Would sunrise still happen? Give a reason for each.
Read the data: two cities, three dates
Sydney and London
Sydney is in the Southern Hemisphere and London is in the Northern Hemisphere. Table 1 compares their daylight on three dates, with the whole Earth’s distance from the Sun on each date.
| Date | Sydney daylight (hours) | London daylight (hours) | Earth–Sun distance (million km) |
|---|---|---|---|
| 4 January | 14.3 | 8.0 | 147 |
| 4 April | 11.7 | 13.1 | 149 |
| 4 July | 10.0 | 16.5 | 152 |
Source: rounded standard values.
4. On 4 July, which city has the longer day? Name the season each city is having, and explain the difference using tilt.
5. Evaluate this claim: “Australia has summer at the start of the year because that is when the Earth is closest to the Sun.” Use Table 1 and what you know about tilt.
Odd one out
A: a leap year (orbit); the others are rotation (1). B: the Sun setting in the west (rotation); the others are tilt (1). C: a 24-hour day (rotation); the others are orbit (1). [3 marks]
Find the error
1. Line 1: the Sun does not move; the Earth rotates, turning our side away from the Sun into shadow (1). Line 2: one rotation takes about 24 hours; 365.25 days is one orbit (1). Line 4: in June the Southern Hemisphere is tilted away from the Sun, so Australia has winter (1). Line 3 is correct. [3 marks]
Question 2
Sun and sunlight arriving at the Earth (1); axis drawn tilted and labelled (1); southern half leaning toward the Sun and labelled (1); season labelled summer (1). [4 marks]
Question 3
No seasons: no hemisphere would lean toward or away from the Sun, so sunlight would hit each place the same way all year (1). Sunrise would still happen, because the Earth would still rotate (1). [2 marks]
Read the data: two cities, three dates
4. London, 16.5 h against 10.0 h (1). London has summer and Sydney has winter (1). In July the Northern Hemisphere is tilted toward the Sun and the Southern Hemisphere away (1). [3 marks]
Question 5
Marking guide: 1 position (the claim is wrong); 1 admits the Earth is closest (147 million km) on 4 January, when Sydney has summer; 1 on that same date London has only 8.0 h of daylight: winter; 1 the whole Earth is the same distance from the Sun on any day, so distance cannot give opposite seasons; 1 the real cause is the tilt of the axis; 1 in January the Southern Hemisphere leans toward the Sun: more direct sunlight, longer days. [6 marks]
Model answer: The claim is wrong. The Earth is closest to the Sun on 4 January, when Sydney has summer, but London has winter with only 8 hours of daylight that day. The whole Earth is the same distance from the Sun, so distance cannot cause opposite seasons. The cause is the tilt: in January the Southern Hemisphere leans toward the Sun, so Australia gets more direct sunlight and longer days.
Common error: accepting the claim because the dates match for Australia.