2. Focus on drinking water
Some people are predicting that future wars will be fought over water – an alarming thought. Water is our most precious resource. How do we ensure that pupils appreciate water and value using it wisely?
The amount of water found on Earth is about 1,400 million million litres. Most of it is found in three places:
- oceans and seas (97%);
- frozen, as ice (2%);
- underground (1%).
There is also some water in lakes and rivers, in the atmosphere and in living things.
Case Study 2 shows an interesting way of combining science and language in a drama activity about water supply. It is important to use a range of different types of activity in science as each pupil will have a preferred learning style – some will learn best through doing, some through seeing and some pupils will be happiest listening.
In Activity 2, you plan and carry out a demonstration that shows how to extract clean drinking water from salt water or dirty water. As with all demonstrations, we suggest you try this out before the lesson and think carefully about the questions you will ask the pupils during the demonstration.
Case Study 2: Thank you for a drink of water
Kholiswa Somyo integrates her pupils’ learning whenever possible. With ‘water’ she linked science to language by making a ‘big book’ with her class. She prepared everything carefully beforehand so that the combined lesson ran smoothly.
She started by involving one of the shyer pupils and developed a little classroom drama. She got Sipho to come to the front and said to him: ‘Nantsi ikomityi yamanzi.’ (Here is a cup of water for you.) Of course, the polite boy said: ‘eNkosi M’am, for the drink of water.’ To which, she surprisingly replied: ‘Don’t thank me! I only gave you the water. Thank the … ’ (and she pointed to the ikomityi).
So Sipho thanked the cup. ‘Don’t thank me,’ said the cup, ‘I only held the water. Thank the … ‘(‘Tap!’ a few children in the class said). ‘That’s right,’ said Kholiswa and got Thembinkosi to come and be the tap.
So Sipho went to thank the tap. ‘Don’t thank me,’ said the tap (Thembinkosi), ‘I only poured the water. Thank the … ’ (‘Pipes!’ called out many pupils).
And so the lesson went on, building up the story of the local water supply, but in reverse; pipes, reservoir, pump-house, and so on. (Read a more detailed description of this lesson with advice in Resource 4: Making a big book.)
Activity 2: Getting clean water
It is possible to make clean drinking water from dirty or salt water. Ask your pupils: How can we do this? Listen to everyone’s ideas and note them down on the wall or chalkboard.
Show your pupils how you can make salty dirty water drinkable. Heat a small quantity of water in a suitable container. Above the container place a piece of glass at an angle leading to another container. When the water boils it will turn to steam. The steam will condense on the piece of glass and drip into the second container. Explain these steps to your pupils. You will need to do this several times and put the important words on the board.
Ask the class to look at the new water and describe it. What is left in the first container? This process is called distillation.
Now ask your pupils to work in groups to do a design for a large-scale version of this experiment. How could they get enough clean water for their home? Ask them to present their ideas and as a class discuss the different proposals. (See Resource 1 for ideas.)