| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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Water of appropriate quality is essential for life. For humans, drinking water should have sufficiently low levels of dissolved salts and microbes. |
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What should the quality of drinking water be like? |
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Urban lifestyles and industrial processes produce large amounts of waste water that require treatment before being released into the environment. |
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What must be done to the waste water produced by urban lifestyles and industrial processes before it can be released back into the environment? |
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Water that is safe to drink is called potable water. Potable water is not pure water in the chemical sense because it contains dissolved substances. |
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What is the name given to water that is safe to drink? Compare the composition of:
• potable water
• pure water.
Why do we not drink pure water? |
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Sewage and agricultural waste water require removal of organic matter and harmful microbes. Industrial waste water may require removal of organic matter and harmful chemicals. |
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What will be required to be removed from a) agricultural waste water and b)industrial waste water? Treating waste water:
https://www.youtube.com/watch?v=YW6GBciRHLg |
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The methods used to produce potable water depend on available supplies of water and local conditions. |
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What factors decide which methods are used to produce potable water? |
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Sewage treatment includes:
? screening and grit removal
? sedimentation to produce sewage sludge and effluent
? anaerobic digestion of sewage sludge
? aerobic biological treatment of effluent. |
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What does sewage treatment include? |
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In the United Kingdom (UK), rain provides water with low levels of dissolved substances (fresh water) that collects in the ground and in lakes and rivers, and most potable water is produced by:
- choosing an appropriate source of fresh water
- passing the water through filter beds
- sterilising. |
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What stages do most of the potable water in the UK produced? |
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Students should be able to comment on the relative ease of obtaining potable water from waste, ground and salt water. |
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How is potable water obtained from a) waste ground and b) salt water? |
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Sterilising agents used for potable water include chlorine, ozone or ultraviolet light. |
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What are three types of sterilising agents used for potable water? Thinking task:
Task students with coming up with a solution to supplying water to a city that only has access to salt water (such as Dubai).
Review ideas and then go through distillation and osmosis. |
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If supplies of fresh water are limited, desalination of salty water or sea water may be required. |
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What process can be used to make salt water / sea water potable when fresh water is limited? |
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Desalination can be done by distillation or
by processes that use membranes such as reverse osmosis. |
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How is desalination completed? (give two methods) Extended writing: Describe the process of desalination.
or
Describe the process of distillation
or
Explain how distillation separates substances. |
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These processes require large amounts of energy. |
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What is the main drawback of desalination processes? |
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Students should be able to distinguish between potable water and pure water. |
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What is the difference between potable and pure water? Think/Pair/Share
Why do we not drink pure water? |
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Students should be able to describe the differences in treatment of ground water and salty water. |
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What is the differences in the way that ground water and salty water is treated? |
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Students should be able to give reasons for the steps used to produce potable water. |
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What are the reasons for each step of producing potable water from ground water? |
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