Year 7 Science · Unit 4 · Lesson 10
Master Worksheet
Learning Goals
Odd one out
In each set, circle the one that does not fit the rule. Then write the set number and your reason on a line below. There is one best answer in each set.
| Set | Rule, then circle the odd one out |
|---|---|
| 1 | Rule: the lit part we see is growing. waxing crescent · first quarter · waning gibbous · waxing gibbous |
| 2 | Rule: true of a lunar eclipse. Earth between Sun and Moon · needs certified eclipse glasses · Moon may look dim red · Earth’s shadow on the Moon |
| 3 | Rule: true of the Moon at every phase. half of it is lit · it reflects sunlight · we see all of its lit half · it orbits Earth |
Find the error
Leo’s revision notes
(1) The phases happen because Earth’s shadow covers more or less of the Moon. (2) The Moon shines because it reflects sunlight. (3) At new moon, the Moon is on the far side of Earth from the Sun. (4) One full cycle of phases takes about 7 days. (5) A solar eclipse can only happen at new moon.
1. Three of Leo’s five sentences contain an error. For each wrong sentence, give its number and rewrite it correctly.
2. In a dark room, a lamp on one side is the Sun, your head is Earth, and you hold a small ball (the Moon) at arm’s length. Predict what you see, and name the phase or event, when: (a) the ball is exactly between your eye and the lamp; (b) you face away from the lamp, holding the ball a little above your head’s shadow; (c) you lower the ball into your head’s shadow.
Plan a test: is Earth’s shadow the cause?
A classmate still blames Earth’s shadow for the phases. Plan a model test with a light, a large ball for Earth and a small ball for the Moon.
Prediction
If the shadow idea were true, a half-lit Moon would need ... on it.
Method (2 steps)
What result would show the idea is wrong?
Read the data: one year of eclipses
Scenario
An astronomy club listed every new moon and full moon for one year, and marked each one that had an eclipse somewhere on Earth.
| Month | New moon | Full moon |
|---|---|---|
| Jan – Feb | no eclipse (2) | no eclipse (2) |
| March | solar eclipse | lunar eclipse |
| April – August | no eclipse (5) | no eclipse (5) |
| September | solar eclipse | lunar eclipse |
| Oct – Dec | no eclipse (3) | no eclipse (3) |
Source: made-up sample year. A number in brackets is how many new or full moons had no eclipse.
3. (a) How many new moons and how many full moons were there in this year? (b) How many eclipses were there in total? (c) What fraction of the full moons had a lunar eclipse?
(c) Fraction of full moons:
4. Every solar eclipse in Table 1 is at a new moon, and every lunar eclipse is at a full moon. Explain why, using the positions of the Sun, Earth and Moon.
5. Mo claims: “If the Moon’s orbit were not tilted, this year would have had 24 eclipses.” Evaluate Mo’s claim, using Table 1.
6. Extended response. Evaluate this statement: “A lamp-and-ball model is just as good as watching the real sky for understanding phases and eclipses.”
Odd one out
1. Waning gibbous: shrinking. 2. Certified eclipse glasses: only for a solar eclipse. 3. We see all of its lit half: only at full moon. (1 each) [3 marks]
Find the error
1. (1) Changing positions of the Sun, Earth and Moon change how much of the lit half we see (1). (3) At new moon the Moon is between the Sun and Earth (1). (4) One cycle takes about 29.5 days (1). [3 marks]
Question 2
(a) The ball blocks the lamp: a solar eclipse, at new moon (1). (b) All of the lit side: full moon (1). (c) The ball goes dark: lunar eclipse (1). [3 marks]
Plan a test: is Earth’s shadow the cause?
Prediction: Earth’s shadow would have to cover half of the Moon ball (1). Method: hold the small ball beside the large ball, at right angles to the light, out of its shadow (1); look from the large ball and note how much of the lit side you see (1). Result: it still looks half lit with no shadow on it, so the idea is wrong (1). [4 marks]
Read the data: one year of eclipses
3. (a) 12 of each (1). (b) 4 (1). (c) 2/12 = 1/6 (1). [3 marks]
4. Solar: the Moon is between the Sun and Earth, its shadow on Earth (1); that is new moon (1). Lunar: Earth must be between the Sun and Moon, with the Moon on the far side of Earth: full moon (1). [3 marks]
5. Mostly agree (1). With no tilt they would line up at all 12 new moons (solar) and 12 full moons (lunar): 24 (1). The orbit is tilted about 5°, so the Moon usually passes above or below the line: only 4 (1). [3 marks]
Question 6
Marking guide: 1 clear position; 1 each for two strengths with an example (e.g. it reproduces the whole cycle; it shows which body is between which for each eclipse); 1 each for two limits (e.g. not to scale; hard to show the 5° tilt; no real timing); 1 judgement weighing both. [6 marks]
Model answer: I partly agree. Moving the balls by hand reproduces the whole cycle of phases and shows which body is between which for each eclipse, which we could never watch from space. But it is not to scale and hard to tilt by 5°, so it cannot show when real eclipses happen. It explains; real observation still checks.
Common error: putting the Moon between the Sun and Earth at full moon.