Year 7 Science · Unit 4 · Lesson 12
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Learning Goals
Sort it: which sky signal?
Each item is something people know or plan on Country. Write it in the box for the sky signal the lesson links it to. The boxes do not all hold the same number of items.
Seven Sisters
Emu in the Sky
Tagai
Phases of the Moon
1. How does a star become a calendar? Write the missing step in each empty box. Each box is caused by the one before it; the second row continues where the first ends.
2. Tagai’s stars form a picture: what is it? Its position shifts over the year: which three things does this help Torres Strait Islander Peoples know?
Read the data: a star and a flowering plant
Scenario
A student kept a record for four years. Each year they wrote the date a bright star (called Star A here) was first seen low in the sky just before dawn, and the date a certain plant (Plant X) flowered.
| Year | Star A first seen | Plant X flowered | Days between |
|---|---|---|---|
| 1 | 12 August | 2 September | 21 |
| 2 | 13 August | 1 September | |
| 3 | 12 August | 3 September | |
| 4 | 12 August | 30 August |
Source: made-up sample record, not from any one Nation. August has 31 days.
3. (a) Complete the last column of Table 1. (b) Work out the mean (average) number of days between Star A and the flowering.
(b) Mean days
4. In year 5, Star A is first seen on 12 August. Predict when Plant X will flower. Explain why Star A’s date changes so little each year, and give one way to make the prediction more reliable.
5. Extended response. Explain how the Seven Sisters, the Emu in the Sky and the phases of the Moon each help people plan on Country: the change in the sky, what it signals, and why that is useful.
Sort it: which sky signal?
Seven Sisters (2): the coming of cooler weather; which foods will soon be available. Emu in the Sky (3): wild emus are nesting; the right time to collect emu eggs; when to leave emu nests alone. Tagai (2): when to plant gardens; the seasons in the Torres Strait. Phases of the Moon (2): the largest tides; safe times to gather shellfish. All 9 = 3; 7 or 8 = 2; 5 or 6 = 1. [3 marks]
Question 1
Box 1: different stars rise at different times of year (1). Box 2: a star first appears low before dawn in the same season every year, because the pattern repeats (1). [2 marks]
Question 2
A figure standing in a canoe, made of stars (1). Its position through the year guides Torres Strait Islander Peoples in knowing the seasons, when to plant gardens and when to fish (1). [2 marks]
Read the data: a star and a flowering plant
3. (a) 19; 22; 18 (1). (b) (21 + 19 + 22 + 18) ÷ 4 (1) = 80 ÷ 4 = 20 days (1). [3 marks]
4. 12 August + 20 days = about 1 September (accept 30 Aug to 3 Sep) (1). Star A barely changes: Earth takes the same time to orbit the Sun each year, so the sky repeats (1). More reliable: a record over many more years (1). [3 marks]
Question 5
Marking guide, 2 per sky signal (1 change and signal, 1 why useful) (each signal must be attributed to the Peoples who hold it). Seven Sisters: many Nations use when it appears to mark a season change, often cooler weather; which foods will soon be ready. Emu in the Sky: seems to run, later sit, as wild emus nest; knowing when not to take eggs protects emus. Moon: full or new Moon brings the largest tides; useful for fishing and gathering shellfish. [6 marks]
Model answer: Many Aboriginal Nations use when the Seven Sisters appears to mark a change of season, often cooler weather, and foods soon ready. The Emu in the Sky, which the Wiradjuri people of central New South Wales know as Gugurmin and many other Nations also recognise, changes position through the year, signalling when wild emus are nesting, so people know when to collect eggs and when to leave them. Aboriginal and Torres Strait Islander Peoples use the phases of the Moon: a full or new Moon brings the largest tides, useful for fishing and gathering shellfish.
Common error: in the sort, placing “the largest tides” with a star instead of the Moon’s phases.