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a clean supply of water is important for people, plants and animals
water can be cleaned by processes such as sieving, filtering, settling, decanting and adding chemicals to kill germs
municipal water is cleaned before and after we use it
Teacher Input 1
Greet the learners.
Ask them what they can remember from the previous lessons on water pollution and importance of
To revise this work in a fun way, you may write key words on big pieces of paper and place these upside down on the table. Learners can draw words at random and then the class must come up with any ideas they can remember about the word from the previous lesson. The following are suggested:
wetlands are like sponges
dambos (the word used to describe wetlands in some African countries)
Tell learners that we are lucky to still have good water sources in South Africa, but we need to take care of this precious resource. In many other countries, but also in parts of our own country, people have to walk very far to get water.
This is a short story about a little girl living Ethiopia and what she needs to do every day to get water to her family. Ask learners:
How many hours does Aleyka spend each day to get water?
Is this water clean (i.e. free from contaminates)?
When does Aleyka do her school homework?
What have you learnt from this video?
Answers can include: Not to waste water; not to take clean water for granted; to be very careful about how we use our water.
There are various ways in which we can clean water. In nature, wetlands help to purify water by acting as filtration systems. Often there are unclean bodies of water that are not suitable for use by humans and animals. We can use chemicals to help clean this water.
People can also carry special purification tablets with them when they are in the wilderness. They can use these to purify the water before drinking it.
Tell learners that we are going to carry out an activity to clean water. We are going to make an apparatus called a “still” which is a water purification device.
Learner Activity 1
Guide learners as they undertake their water purification investigation (using a still) as required in WORKSHEET A: Investigation – Purifying water in a still.
Explain how the completed WORKSHEET A will be assessed.
Support learners as they write down their observations in the worksheet at the end of the investigation.
Teacher to use WORKSHEET A: Memorandum to mark the learners’ work.
Teacher Input 4
Present an overview of the different ways in which water can be purified by using PRESENTATION 1: Processes to purify water.
Tell learners that they will be required to design and build a water filtration system that they could use to purify water, if there is no electricity (to boil water) or chemicals (like bleach).
Learners complete the activity as a project in class.
Should design and build their own simple system to filter dirty water.
Can adapt the water filter design discussed earlier in this lesson – using recycled materials as much as possible.
Should plan and draw their design on a piece of paper
Must build the actual filter as per their design (using recycled materials).
Should test their water filter and demonstrate the working of the filter to the class.
Support learners as they undertake this designing activity and explain how their work will be assessed.
Teacher Input 6
Tell learners that we have now discovered how to purify water through filtering.
Recap work done up to this point by using PRESENTATION 1: Processes to purify water again. – adapt if we get pictures from Derrick
We are fortunate to live in a country where the tap water is normally clean enough to drink.
In many countries, such as India, clean water is very scarce. In Europe, people buy bottled water to drink, because tap water is often not suitable to drink.
Many of us are fortunate to have a supply of tap water at our homes. This water supply is managed by the municipalities in the different towns.
Ask learners if they know where tap water comes from. How does it get to our homes?
Answers: Water comes from a river or dam or sometimes waste water from factories is used. Water is then cleaned by the municipality through special processes and relayed to our homes through a network of pipes.
The place where water is purified by the municipality, is called the water treatment plant.
Present an overview of how municipal water is treated by using PRESENTATION 2: Treatment of municipal water
Explain to learners that there are five processes in the treatment of water. These processes are-
Learner Activity 4
Tell learners that they must see if they can match up the processes of treating municipal water with the correct descriptions in WORKSHEET C: Processes in treatment of water.
Learners complete WORKSHEET C.
Support learners as they undertake this activity and explain how their work will be assessed.
Teacher to use WORKSHEET C: Memorandum to mark the learners’ work.
Teacher Input 7
For revision purposes, show video clip 6. This video will help learners remember the five important steps that are used to treat municipal water.