Year 7 Science · Unit 2 · Lesson 12
Foundation Worksheet
Learning Goals
True or false? Fix the false ones
Circle T or F. If a statement is false, correct it on the line.
1. Clouds are made of water vapour, an invisible gas.
Correct it:
2. Infiltration is water flowing over the surface of the ground into a creek.
Correct it:
3. A gum tree adds water vapour to the air through its leaves.
Correct it:
4. Most of Earth’s water is fresh water in rivers and lakes.
Correct it:
5. Gravity pulls rain down from clouds and makes runoff flow downhill.
Correct it:
1. Describe the difference between infiltration and runoff.
Fill the gap: rain to Sydney’s dam
Choose the correct word from the word bank. Each word is used at most once. Two words are not needed: cross them out.
Rain and hail fall on the bush west of Sydney as . Some of the water soaks into the soil by , which tops up the stored in rock underground. Water that does not soak in flows over the land as , into rivers that fill Warragamba Dam. On sunny days the Sun’s energy causes from the surface of the dam. Gum trees around the dam release water vapour from their leaves by . High in the sky the water vapour cools, and forms new clouds.
Sort it: can people easily use this water?
Write each water store in the correct box. The boxes do not hold the same number of items.
Easy to use (accessible fresh water)
Hard or impossible to use
Read the data: where does the rain go?
Scenario: four trays in the rain
A class filled four trays with different surfaces and tilted each tray at the same angle. They sprinkled 500 mL of water over each tray, like rain, and collected the water that ran off the low end. Water that did not run off had soaked into the surface.
| Surface | Water sprinkled (mL) | Water that ran off (mL) |
|---|---|---|
| Concrete paver | 500 | 460 |
| Packed clay soil | 500 | 310 |
| Grass growing in soil | 500 | 120 |
| Loose sand | 500 | 40 |
Source: sample class results.
2. How much water soaked into the grass tray? Show your working.
Answer mL
3. City streets and car parks are covered in concrete. Use Table 1 to explain why heavy rain in a city causes a lot of runoff, and why less water tops up the groundwater.
4. A water molecule starts in the Pacific Ocean and ends up coming out of a tap at your school. Describe its journey. Name at least four water cycle processes in the right order, and say what provides the energy for two of the steps.
True or false
1. False: clouds are tiny droplets of liquid water, formed when water vapour cools and condenses. 2. False: that is runoff; infiltration is water soaking into the soil. 3. True. 4. False: about 97.5% of Earth’s water is salt water in the oceans; rivers and lakes hold only about 0.013%. 5. True.
Question 1
Infiltration: water soaks down into the soil and rock, topping up groundwater (1). Runoff: water flows over the surface of the land into rivers, lakes and the sea (1). [2 marks]
Fill the gap: rain to Sydney’s dam
precipitation; infiltration; groundwater; runoff; evaporation; transpiration; condensation. Not used: salt water, desalination.
Sort it: can people easily use this water?
Easy to use: the Murray River; the lake behind Warragamba Dam; a shallow aquifer reached by a farm bore. Hard or impossible: the Pacific Ocean (salty); the Antarctic ice sheet; glaciers on high mountains (frozen); groundwater far too deep to pump.
Question 2
500 − 120 (1) = 380 mL (1). [2 marks]
Question 3
Concrete let 460 of 500 mL run off, the most of any surface (1). So in a city most rain becomes runoff that rushes into drains and rivers (1), and very little infiltrates to top up groundwater (1). [3 marks]
Question 4
Marking guide: 1 evaporation from the ocean; 1 condensation into cloud as the vapour rises and cools; 1 precipitation over the land or catchment; 1 runoff into a river and dam, or infiltration into an aquifer, then piped to the tap (these four in a correct order); 1 energy for two steps: the Sun for evaporation, gravity for precipitation or runoff (both needed). [5 marks]
Model answer: The Sun heats the ocean and the molecule evaporates into water vapour. The vapour rises, cools and condenses into a cloud droplet. The droplet grows heavy and gravity pulls it down as rain on the hills west of Sydney. It flows downhill as runoff into a river and into Warragamba Dam, and is then treated and piped to the school tap.
Common error: calling clouds “water vapour”. Water vapour is invisible; a cloud is liquid droplets.