Year 7 Science · Unit 4 · Lesson 9
Foundation Worksheet
Learning Goals
Fill the gap
Choose the correct word from the word bank. Each word is used at most once. Two words are not needed: cross them out.
A tide is the regular daily rise and fall of the . When the water is furthest up the beach it is , and when it has pulled furthest back it is . The difference in height between the two is the . The Moon’s pulls the ocean into a on the side of the Earth facing the Moon, and there is another one on the far side. So most coasts get about high tides a day. Tides are , so tide charts can be printed years ahead.
True or false? Fix the false ones
Circle T or F. If a statement is false, correct it on the line.
1. The Sun also pulls on the ocean, but its pull on the tides is weaker than the Moon’s.
Correct it:
2. The main cause of tides is the wind blowing the sea onto the beach.
Correct it:
3. Spring tides only happen during the season of spring.
Correct it:
4. Spring tides happen at new Moon and full Moon, when the Sun, Earth and Moon line up.
Correct it:
5. At Broome in Western Australia, the difference between high tide and low tide can be more than 9 metres.
Correct it:
6. A neap tide has the biggest tidal range of the month.
Correct it:
Sort it: spring or neap?
Write each item in the box for the tide it goes with. The boxes do not hold the same number of items.
Spring tide
Neap tide
1. Sketch the Earth, and the Moon to its right. Show the sea piled up on two opposite sides. Label both high tide places, one low tide place, and an arrow for the Moon’s pull.
Read the data: a day at the beach
Scenario: rock pools
A family is spending a Saturday at a New South Wales beach. They want to explore the rock pools, which are only uncovered near low tide. Table 1 is the tide table for that day.
| Time | Tide | Height (m) |
|---|---|---|
| 3:20 am | Low | 0.2 |
| 9:35 am | High | 1.6 |
| 3:50 pm | Low | 0.4 |
| 10:05 pm | High | 1.5 |
Source: sample tide table for this worksheet.
2. Count the high and the low water times in Table 1. Why does the count fit the two bulges?
3. The family is at the beach from 8 am to 6 pm. When should they visit the rock pools? Explain your choice, and why they must keep watching the time.
4. A Year 5 student asks you why the sea at the beach goes up and down twice a day. Write an explanation for them.
Fill the gap
sea; high tide; low tide; tidal range; gravity; bulge; two; predictable. Not used: wind, ten.
True or false
1. True. 2. False: the main cause is the Moon’s gravity. 3. False: spring tides happen all year, at new and full Moon; the name means the tide “springs up”. 4. True. 5. True. 6. False: a neap tide has the smallest tidal range.
Sort it: spring or neap?
Spring (5): new Moon; full Moon; Sun, Earth and Moon in a line; pulls add together; biggest tidal range. Neap (4): first quarter Moon; last quarter Moon; Sun and Moon at right angles; pulls partly cancel.
Question 1
Two bulges drawn, one facing the Moon and one on the far side (1); both labelled high tide, with low tide labelled between them (1); arrow for the Moon’s pull toward the Moon (1). [3 marks]
Read the data: a day at the beach
2. Two high and two low tides (1). The Earth spins once a day, carrying the beach through both bulges and both low places (1). [2 marks]
3. Around 3:50 pm (1), the only low tide while they are there, so the pools are most uncovered (1). After that the tide comes back in, and a fast incoming tide can cut off the way back (1). [3 marks]
Question 4
Marking guide: 1 a tide is the regular daily rise and fall of the sea; 1 the Moon’s gravity pulls on the ocean water, which flows easily; 1 a bulge on the side facing the Moon; 1 a second bulge on the far side; 1 the Earth spins once a day, so each coast passes through both bulges: about two high tides. [5 marks]
Model answer: A tide is the daily rise and fall of the sea. The Moon’s gravity pulls the ocean into a bulge on the side of the Earth facing the Moon, and there is a second bulge on the far side. As the Earth spins once a day, each coast passes through both bulges, so it gets about two high tides and two low tides.
Common error: drawing only one bulge, facing the Moon.