MATTER AND MATERIALS GRADE 5. Western Cape Primary Science Programme (PSP) An example of a learning experience in the Natural Sciences

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1 Western Cape Primary Science Programme (PSP) An example of a learning experience in the Natural Sciences MATTER AND GRADE 5 MATERIALS Water is Precious 1 Solids, liquids and gases 2 Mixing solids and liquids 3 Which solids are soluble and which solids are insoluble in water? 4 Can we make a solid dissolve faster? 5 Can we get the solids back after we have mixed them with water? 6 Water is a precious liquid 7 Making polluted water clean again 8 Making sewage water clean again 9 How do we get clean drinking water? We welcome the wide use of these materials. Please acknowledge PSP PSP 2008

2 DEVELOPED BY WESTERN CAPE PSP team AND TEACHERS These materials were written to support teachers in their work with learners around the content area of Matter & Materials. While this is not a complete work schedule, it offers possibilities for teachers to include other learning experiences and to extend and develop this further. This example learning experience shows how you can work towards the following learning outcomes in the Natural Sciences. LO1: Scientific Investigations The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts LO2: Constructing Science Knowledge The learner will know and be able to interpret and apply scientific, technological and environmental knowledge LO3: Science, Society and the Environment The learner will be able to demonstrate an understanding of the interrelationships between science and technology, society and the environment. Courses presented by Rose Thomas and Nontsikelelo Mahote Booklet designed by Welma Odendaal Illustrated by Nicci Cairns and Janet Ranson Western Cape Primary Science Programme Edith Stephens Wetland Park Lansdowne Road Philippi, 7785 P O Box Lansdowne 7779 South Africa Tel: Fax: info@psp.org.za website: ww.psp.org.za The PSP is grateful for support from PETROSA

3 Contents Section 1 Learning Experiences 1 Solids, liquids and gases Mixing solids and liquids Which solids are soluble and which solids are insoluble? Can we make a solid dissolve faster? Assessment Task for LO Can we get the solids back after we have mixed them with water? Water is a precious liquid Making polluted water clean again Making sewage water clean again Assessment Task for LO How do we get clean drinking water? Assessment Task for LO Suggested Work Schedule Section 2 Teacher Resources Task cards to photocopy Assessment task cards , 48, 50 A3 diagrams and pictures to photocopy Section 3 Extracts from NCS Core knowledge and concepts in Matter and Materials Learning Outcomes and Assessment standards

4 Section 1 Learning Experiences Assessment tasks LO LO LO Work Scheme

5 1 Key concepts g Matter exists in 3 different forms: solid, liquid and gas. g Solids, liquids and gases have their own characteristics and properties. what can i say about a book? Solids, Liquids and Gases Teacher Task Introduction Revise the 3 states of matter: solids, liquids and gases. Show your learners many examples of different kinds of matter and ask them to help you sort them into solids, liquids and gases. Choose an example of a solid, liquid and a gas. Remind your learners that the different forms of matter have different properties. A book The pages are smooth It is solid It is brown I can bend it The cover is hard what can we say about this cool drink? IT CAN BURN! I can fold it Acooldrink We can pour the water We can drink it It is runny We can see through it It is wet It takes the shape of the container 1

6 Poem about water and its properties The rain Swishing, swashing down the lane, Come the lorries in the rain. Shunkle, shonkle is the mutter Of water flowing down the gutter. Shillop, shallop, through the mud, what can we say about the air in a balloon? Go the cows chewing the cud. Splashing, splishing, cars go by, But I m inside and nice and dry! air It presses on the inside of the balloon We can squash it It takes up all the space inside the balloon It makes a sound if we let it out It can escape It floats We can compress it It bounces Consolidation Remind your learners that the properties of solids are the things that all solids have in common. Similarly, the properties of liquids are something that all liquids have in common. The properties of gases are the things that all gases have in common. 2

7 Write the table on the chalkboard and ask your learners to help you to complete it. Afterwards they can copy the completed table into their books. Summary The properties of solids, liquids and gases Form of matter Everyday examples Properties Solid book, eraser, brick, All solids keep their cup, table, pot, shape. chair, tin, pencil Liquid tea, water, milk, All liquids can pour. cool drink, juice, All liquids are runny. washing-up liquid All liquids take the shape of their container. Gas bubbles in Coca-Cola, Gases spread out air, motor car fumes, and fill the available smell of vinegar, smell space. of onion, smell of perfume When a gas is in a container it spreads throughout the whole container. 3

8 2 Key concepts g Certain solids dissolve in water eg, salt and sugar. We say they are soluble in water. g Some solids cannot dissolve in water. We say they are insoluble. g When we mix solids and liquids: If the solid is soluble we get a special mixture called a solution Learner Task Task card to photocopy on page 37. Mixing solids and liquids Teacher Task Introduce Discuss with your learners some everyday examples of when we have to measure solids and liquids and then mix them together to make something (eg making porridge, vetkoek, bread; mixing cement, gravel, sand and water to make concrete for building; or mixing coffee and water to make a cup of instant coffee, etc). Give your learners the opportunity to do the following activity in groups. Make sure that every child in the group participates and gets the chance to measure and mix. Check that your learners have done some measuring with syringes, medicine spoons and small measuring cylinders. You will find a section on measuring in the Grade 4 Matter & Materials booklet. Mixing solids and liquids to find out what happens Mix together Mix together 1 medicine spoon of sand 1 medicine spoon of salt 100ml 100ml 100ml of water Draw and label to show what happened 100ml of water Draw and label to show what happened. 100ml 100ml sand The salt has disappeared The sand has not dissolved in the water. We say that the sand is insoluble in water. The salt has dissolved in the water. We say that the salt is soluble in water 4

9 Teacher Task Explain Solutions Discuss the difference between the two mixtures. Refer to the salt and water mixture in which the salt dissolves. Introduce the terms dissolve, solute and solvent and solutions Draw and explain these diagrams on the chalkboard. How to make a solution salt water salt-water solution We say the salt has dissolved. This salt water is now called a solution. It is a special kind of mixture because the solid has dissolved in the liquid. Mixtures Refer to the mixture of sand and water. Introduce the term insoluble. Draw and explain these diagrams on the chalkboard. How to make a mixture sand water sand and water mixture The sand can still be seen in the water. We say it is insoluble in water. This sand and water is not a solution. 5

10 Consolidation Write these sentences on the chalkboard and learners can copy them into their books. SOLUBLE AND INSOLUBLE We say a solid is soluble when * It disappears when mixed with water. * It does not settle to the bottom after some time. * It does not separate from the water when passed through a filter. We say a solid is insoluble when * It does not disappear in water. * It settles to the bottom after some time. * It separates from the water when passed through a filter. note to teachers DISSOLVED Instant coffee (and filter coffee) has some substances dissolved in it which pass through filter paper. But instant coffee also has some solids which do not dissolve. The solids which do not dissolve are caught by the filter paper. Solution Solution Funnel Nothing solid is left in the filter paper NOT DISSOLVED Mixture Funnel Solids are left in the filter paper Clean liquid (water) 6

11 note to teachers Helping children to decide whether a solid has dissolved or not When you mix flour and water, or Maizena and water, or mieliemeel and water, it is sometimes difficult to tell whether the solid has dissolved. This is because the solid has spread uniformly throughout the mixture. But if you let the mixture stand for a while (sometimes even overnight), you will find that the solid settles to the bottom. This means it is not a solution. The solid has not dissolved. In a solution, even if you let it stand for a long time, the solid will not sink to the bottom - it remains in the solution. Usually you can see right through a solution even if it has changed colour. You can see through it like coloured glass. If you are still not sure, you can filter the mixture. If it is a solution, everything will go through the filter paper. If it is not a solution, the solid will be caught in the filter paper and the liquid will go though. Further discussion Start a discussion about mixtures and solutions. Explain that a solution is a special kind of mixture because after you have mixed the solid and the liquid the solid seems to disappear. Ask your learners: Do you think the solid has really disappeared? Where did the solid go? Do you think the solid is still in the solution? Explain why you say so? What do you think happens to the solid in the solution to make it disappear? Is the water still pure water after the salt has dissolved in it? Accept a wide range of ideas and explanations from your learners. 7

12 3 Key concepts g Certain solids dissolve in water eg, salt and sugar. We say they are soluble in water. g Some solids cannot dissolve in water. We say they are insoluble. g When we mix solids and liquids: If the solid is soluble we get a special mixture called a solution Learner Task Which solids are soluble and which solids are insoluble? Teacher Task Preparation Provide the following equipment: Water Filter paper Filter funnel Cups or baby food bottles Medicine spoons A selection of soluble and insoluble solids to test. (It would be best if the learners can bring some from home.) Which solids are soluble and which solids are insoluble? 1. Bring some solids from home and test them to see if they are soluble or insoluble in water. 2. Take water and different solids and mix them. Then complete the table. Task card to photocopy on page 38. Mix Does the solid Does the solid Can the solid Is the solid Do we have a 5ml solid + 100ml disappear in settle to the be separated soluble or solution here? water the water? bottom after by the filter insoluble? some time? paper? 5 ml flour + 100ml No Yes Yes Insoluble No water 5 ml Epsom salts Yes No No Soluble Yes ml water 5 ml Bicarbonate Yes No No Soluble Yes of soda ml water 5 ml Maizena + No Yes Yes Insoluble No 100 ml water 8 3. Draw and write to explain how you can tell whether a solid is soluble. Then draw and write to explain how you can tell when a solid is insoluble. Use some of the words in the table above to help you.

13 Solutions What things must you look for to decide if the solid is soluble in water? Mixtures What things must you look for to decide if the solid is not soluble? We can see through the liquid No solid on the filter paper Solid has disappeared Clear liquid Solid can be seen Liquid can be clear or cloudy Solid on the filter paper Clear or cloudy liquid Questions Discuss these questions in your group. 1. Why did we use the same amount of solid and water every time? (So that we can make a fair comparison.) 2. Does the amount of solid and water we use make a difference? (Yes, because if we use a lot of solid and a little water, it won t dissolve.) 3. What would happen if we kept adding more and more of the solid to the solution? (Eventually no more will be able to dissolve.) 4. Could we get the solid back again after it has dissolved? How do you think you could do this? (Yes, we could boil off the water.) has this dissolved? i can t tell. try shaking it. no, try letting it stand for a while. can you see through it? 9

14 4 Key concepts g We can speed up the time it takes for a solid to dissolve. g We can speed up dissolving by: heating the solvent grinding up the solute into small pieces shaking or stirring the solution. Can we make a solid dissolve faster? Teacher Task Preparation Prepare the learners for the investigation. Explain that they are going to experiment to find the fastest way to dissolve medicine spoons of solid. They can use any solid that dissolves in water. Explain that every investigation starts with a good question. Discuss Ask these questions to get your learners thinking about how they will do the investigation. 1. What do you think will make the solid dissolve faster? 2. What can you do to the solid to make it dissolve faster? 3. What can you do to the water to make the solid dissolve faster? 4. What do you think will make the solid dissolve slower? 5. What will we have to measure if we want to find out how long a solid takes to dissolve? (We will have to measure the time.) do the big lumps dissolve more slowly than small lumps? do different solids dissolve at different speeds? will the sugar dissolve slower if i use less water? Developing questions for investigations Class discussion 1. Suggest the following question for investigation: Which will make sugar dissolve faster: hot water? tap water? fridge water? (The learners can use salt or sugar in their investigations.) 2. Ask your learners to add more questions of their own. Try to phrase them in the same way. 10

15 The following are two other examples of questions that could be investigated. Which will dissolve faster? 1 spoons of sugar? 2 spoons of sugar? 3 spoons of sugar? Which will make sugar dissolve faster: stirring it 10 times? stirring it 20 times? stirring it 30 times? See the assessment standards for LO1, grade 5 on page Ask learners to suggest some ways that they could go about doing these investigations 4. Ask each group to choose one of the questions to investigate.you will need to help them to set up their investigations. Note In an investigation the learners have to: Plan an investigation by suggesting things that could be investigated Carry out an investigation involving a small number of steps Report back about what they did and what they found out On the following page is an example of an assessment task for an investigation which works towards these assessment standards. 11

16 Assessment Task for LO1 Investigation: Can we make a solid dissolve faster? Investigation: Can we make a solid dissolve faster? Before you start the investigation: Choose or help to think up a question to start your investigation. Discuss how you will set up the investigation. Then do the investigation. 1. Write down the question you are investigating Question: Which will make sugar dissolve faster: fridge water? tap water? hot water? Task card to photocopy on page 40. fridge water tap water hot water 1 spoon sugar 1 spoon sugar 1 spoon sugar 100ml water 100ml water 100ml water 2. Draw how you set up the apparatus. 3. Record the time it takes for the sugar to dissolve.do not stir the mixture. 4. Record your observations on the recording sheet: Amount of sugar Amount of water Temperature of Time taken for sugar the water to dissolve 1 spoon 100ml fridge 8 minutes and 50 seconds 1 spoon 100ml tap 6 minutes 1 spoon 100ml hot 3 minutes and 20 seconds 5. Draw a graph of your results. 6. Share with another group. Explain to them what you did and what you found out 7. Exchange your results with another group who investigated a different question 8. Draw a graph of their results. Discuss: What did you learn from them? There are more examples of investigations on page 42 and 43. Assessment task for LO1 (cont) note to teachers We used the same amount of water and sugar and the bottles were the same size. This ensured that we could make a fair comparison between the different water temperatures and how quickly the sugar dissolved. 12

17 Assessment task for LO1 (cont) y Graph to show how fast the sugar dissolves in fridge water, hot water and tap water Time (minutes) Fridge water Tap water Hot water x Temperature of water ASSESSMENT CRITERIA Assessment Task Investigation to find out if we can make a solid dissolve faster Assessment Criteria Planning the investigation Learners must be able to: Contribute to thinking up a suitable question for investigation. Contribute useful ideas about how to carry out the investigation. Conduct the investigation Learners must be able to : Take regular readings and record these on a suitable table The readings must be reasonable and accurate. Learners must draw a graph to show their results. The graph must be correctly plotted. The graph must have a suitable heading, labelled axes and a suitable scale. Report on their findings Learners must be able to : Explain with confidence what they did and what they found out. 13

18 Teacher Task note to teachers If this is the first time that the learners draw a graph, they will need a great deal of help. Draw a bar graph on the chalkboard and explain how we draw and label the axes. Use a suitable scale and write a heading. Let your learners copy this graph into their books so that they can refer to it when they draw their own. What have we learned? Discussion This is a useful way to get your learners to share what they have found out and learned from the investigation. Ask two learners from each group to move to another group. They need to take their group s results and the graph that they made to share with the new group. Then they should explain to the other group what they did and what they found. Then together they should discuss their results. The questions below should guide them. 1. Did your investigation give you an answer to your question? 2. Was it the answer you expected? 3. Was your investigation accurate? How could you have improved it? 4. What does your graph tell you? 5. What do the other graphs tell you? Note to teachers on how to facilitate this Whilst learners are planning Help learners to think up some ways to make solids dissolve faster Then help them to formulate these ideas into questions. You can structure the questions in the following ways: If we heat the water will the salt dissolve faster? What will make the salt dissolve faster? Hot water or tap water or fridge water? Whilst learners are setting up their apparatus Check that they are measuring the amounts of their solids and liquids. Check that they are able to handle the apparatus confidently. Help them to record the time by using a clock or wristwatch. Otherwise they can count the seconds by saying: one and two and three and four (four seconds). Whilst learners are making observations Check that the learners have recorded their findings in a suitable table. Check that their results are reasonable and accurate. Helping learners to draw a graph Choose a group with a good set of results. Use these results to show learners how to make a bar graph of their results. Do this on the chalkboard with the whole class. 14 How to decide what to put on each axis The thing that you will observe or measure during the course of the investigation will be recorded on the y-axis. The thing that you made sure will stay the same throughout the investigation is what we put on the x-axis.

19 For example: you put the time here on the y (or vertical) axis because that is what you are trying to find out. you put the different substances and amounts that you chose and set up on the x (or horizontal) axis. How to decide what to put in the heading The heading for the graph depends on what you are recording on each axis. Start the heading with the words, Graph to show, and then say what you are measuring. You will need to refer to what is on each axis. For example: Graph to show how fast (y axis) sugar dissolves when we use different amounts of sugar (x axis). note to teachers This is a good opportunity to help your learners use the terms, more quickly, less quickly ; bigger amount, smaller amount ; etc. Consolidation Help learners to interpret the graphs in a class discussion. This is a very important step. There is no point in drawing a graph if you don t also interpret what the graph is telling you. Learners need help and practise to interpret graphs. If they make their own, they are more likely to understand the purpose of graphs and how they work. Use these questions to help you guide your learners. Write the answers on the chalkboard. What effect does heating the liquid have on the dissolving? (When we increase the temperature of the water, this should speed up dissolving.) When we increase the amount of solid what effect does it have on the dissolving? (The more solid we have, the longer it takes to dissolve in the same amount of water.) When we stir the mixture, what effect does it have on the mixture? (The more you stir the mixture, the more quickly it dissolves.) Summary Write this on the chalkboard so that your learners can copy it into their books. What do the graphs tell us? What we learnt about dissolving We have learnt that a solid dissolves more quickly in hot water. We have learnt that a bigger amount of solid dissolves more slowly. We have learnt that a solid dissolves more quickly when we stir the mixture more times. Etc. 15

20 5 Key concepts g When a solid is insoluble we can separate it from the mixture by letting the solid settle to the bottom and then decanting (pouring off) the water, and drying the solid filtering (sieving) the mixture so that the solid stays behind on the filter paper g When a solid is soluble we can separate it from the solution by allowing the water to evaporate by putting it in a warm place or boiling the solution until all the water has evaporated.the solid will crystallize and be left behind in the container. Can we get solids back after we have mixed them with water? Teacher Task Tell your learners a story which will bring out the idea of decanting, sieving and getting substances back out of solutions and mixtures. Try to make sure that the story is about something which your learners are likely to be familiar with. For example, straining home-brewed beer, or sieving rice. decanting sieving 16 Explain water evaporating Make a salt solution Introduce the idea that when we have dissolved some salt in water, the solution looks like pure water. But when we drink the solution, we can still taste the salt. Get your learners to prove this by tasting the solution. This is because the salt has not disappeared. It has just spread out in the water. Explain that we can get the solid back by evaporating the water from the solution and then we are left with the solid. The water can be evaporated by boiling it. Another way we can evaporate the water is to spread it out in a shallow container and stand it in a warm place. The process of getting the solid back from a solution is called crystallization.

21 Preparation Provide the following apparatus note to teachers It is best to demonstrate this with salt. If you use sugar, it often burns before it crystallizes. matches Learner Task A Can we get the solid back from a solution? 1. Boil a small amount of salty water until the salt has crystallized. 2. Pour a small amount of salty water in a saucer or lid and place it in a warm dry place. 3. Make a labeled drawing to explain what happened to the salty water. Use these words to help you: evaporate, crystallize, boil Questions Discuss these questions in your group. When you boiled the salty water: What happened to the water? Where did it go? What happened to the salt? Do you think you could get the water back from a solution? How would you do this? Task card to photocopy on page

22 Task card to photocopy on page 44. Learner Task B Home Project Looking for examples of settling, decanting, filtering (sieving), crystallizing and evaporating in our daily lives hand-made metal strainer with small holes. beer sieve 1. Look at home to find as many examples as you can of the ways we do settling, decanting, filtering (sieving), crystallizing and evaporating in our daily lives. 2. Draw and write about how we make use of decanting, filtering (sieving), crystallizing and evaporating around our homes. note to teachers Your learners may struggle to find examples of crystallizing in their daily lives. Don t worry if they are unable to do so. The important thing is for them to try to find ordinary examples of these processes. Consolidation Check that your learners have found good, correct examples of these processes from home. Check, too, that they show they understand what these concepts mean. If necessary, explain the concepts soluble and insoluble again to learners. Then explain the new concepts, evaporation, decanting and settling, filtering, crystallizing. These terms will be used again and again in the learning experiences that follow. 18

23 6 Key concepts g Water is precious because it is so useful to us. g All life depends on water. g We use it for cleaning, drinking and cooking. Water is a precious liquid Teacher Task Find a story (or ask your learners to bring one), which illustrates the importance of water. Tell it to your class. Discuss why it is important to have clean water. Introduce the idea that one of the reasons why water is so useful to us is because of its properties. It is runny. So we can use it to rinse things. For example to wash the sand off our hands. The runniness of the water washes the insoluble sand off our hands. It is a good solvent. This means that all sorts of substances are soluble in water. So we can use it to dissolve some of the dirt and stains out of our clothes. Soaps and washing powders help in this process. We also use it to dissolve things when we prepare food and when we cook. For example, making jelly, making tea with sugar, making gravy from meat juices, and so on. It flows. So we can use it to carry things in boats. But we also use it to carry away unwanted substances like sewage from our toilets. Explain Water is also essential for life. This is because most of the chemical reactions and life processes which take place inside the bodies of plants and animals depend on water. For example, photosynthesis depends on water. In other words, plants make their own food, using water as one of the ingredients. A plant also depends on water to transport nutrients around its body. The human body depends on water, which makes up the major constituent of the blood and cells. Because we use water in so many ways, it becomes polluted. Then it is difficult to make the water clean again so that plants and animals can use it. But how does water become polluted? The next task will demonstrate how water becomes polluted. The task will remind learners that everything that gets washed, poured off, and carried by water eventually pollutes that same water. 19

24 Discuss Ask your learners about the different ways that they use water. Then ask them about the things that they put into water. Ask: When you wash with water, what are some of the things that you add to the water to make washing easier? (Soap, shampoo, bath salts, bubble bath, bath oil, dishwashing liquid, etc.) When you clean toilets and floors, what do you add to the water? (Bleach, Handy Andy, antiseptics, Dettol, Jeyes fluid, etc.) When you wash your clothes, what do you add to the water? (Soap, detergent, bleach, fabric softener, etc.) When you wash the dishes, what do you add to the water? (Soap, dish washing liquid, etc.) When you cook, what things do you add to the water? (Salt, pepper, spices, herbs, etc.) Ask your learners to think of all the other things that people use when they wash. For example, when they wash motorcars, motorcar engines, carpets, windows, etc. Try to get learners to think of as many different examples as they can. Remind your learners that anything that we pour onto the ground or into the soil eventually gets into the water. Farmers also use fertilizers on their land. When it rains, this polluted water sometimes runs off into the rivers. Sometimes the polluted water sinks into the ground and then ends up in the rivers. Everything we add to water eventually pollutes our rivers and seas. Ask your learners What else makes water dirty? (Leaves, grass, papers and plastics, oil poured into water, sticks, dust, sewage, etc) 20

25 Learner Task Task card to photocopy on page 45. note to teachers Make sure that the learners keep their bottles of dirty water for the next learning experience when they will try to make it clean again. Group work How does water become polluted? 1. Look at home and find all the things that you add to water when you are washing, cleaning and cooking. 2. Bring a small sample of each substance to school. 3. Show and tell to your group what you have brought. 4. Take a bottle or some container that has a lid. Add clean water to it. 5. Now mix all the things you brought from home into the water. 6. Also add some dead leaves and grass and some soil. Discuss In your group, discuss these questions. What does your water look like now? Would you drink this water or wash with it now? Which of the things that you added to the water have dissolved? Which of the things that you added to the water did not dissolve? When you pour this water down the drain, where will it go? What will happen to the substances in the water? Where will they go? How can we make the water clean again? 21

26 22 7 Key concepts g Water can be polluted by solid substances (soluble as well as insoluble). g Polluted water can be made clean again by carrying out purifying processes eg, decanting and settling, filtering, evaporating and crystallizing. g Water may contain dissolved substances such as poisons, which make the water dangerous to drink. Many rivers in the world are polluted. Can you see what is happening to this river? B What was done to save this river? Making polluted water clean again Teacher Task Hand out pictures of water pollution. Photocopy picture A on pages ) Discuss with your learners how water becomes polluted. Refer to the picture of the polluted river as you ask them the following questions. What are all the things that cause pollution in this river? Do you think this picture shows all the ways that water can be polluted? Is there anything you would add to this picture to show another kind of pollution? Does it matter that the water is polluted? (Let learners argue both sides of this issue) How does a polluted river affect people, plants and animals? Refer to the drawing of the river that has been cleaned up. (Photocopy picture B on pages ) A Ask your learners: What did the people do to clean up this river? In what ways did these things help to clean up the river? Look at the picture of the boys playing on the water near their homes in Nyanga on page 23. Ask your learners, Do you think these boys are having fun? What do you think about children playing like this? Do you think this is a safe place for these boys to play? Is the water at this place clean? What are some of the things that could pollute it? Where do you think that this water comes from? What will happen if the boys drink this polluted water? What can the community do to make it safer for the boys to play here? Ask your learners to make a play, or a story, or a rap song about what could happen to the boys who swim here. Tell them to think what could happen if they drank some of this polluted water. They should also think about what the community could do to make this a safer place to play a place with with cleaner water. In their play, song or story they must describe the consequences of having contact with polluted water, such as illness. They should also suggest ideas of suitable steps to take to improve the environment, for example, moving the toilets further from the water, cleaning up the litter and disposing of it properly, etc.

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28 Task card to photocopy on page 46. Learner Task Card A What we can do to improve our environment and the water nearby? Make up a play, or a story, or a rap song about what happened to the boys who swam in the river, and how the people cleaned up the river. What would happen if one of them drank some of the water? What did the community do to make this a safer place to play? How did the people make the water cleaner? Teacher Task Discuss different ideas about how to make water clean again when it is dirty. Get your learners to bring out their containers of dirty water. Provide a table full of different equipment eg fabric, cotton-wool, filter paper and funnels, glass baby-food jars, spirit burners, tripods, gauze, tissues and toilet paper. Ask your learners to choose anything on the table to make their water clean again. Then ask your learners to tell you how they made the water clean. Tell them that they can do this in the form of a report, a story with pictures, or a rap song. As they report on what they did (in any language), they should use vocabulary like, pour, decant, strain, filter, settle, etc. 24

29 Task card to photocopy on page 47. Learner Task Card B Making polluted water clean again 1. Group task: Use anything on the table to make the water clean again. 2. Draw and tell a story with pictures, a rap song or a report to show how you made the water clean. Questions to discuss: Did you manage to make your water clean again? Was it completely clean and pure? Was it clean enough to drink? Explain why you think so? Funnel Toilet paper Cut-off cooldrink bottle Dirty water Gauze Filter paper Baby food jar Cotton wool Empty bottle Write to explain how you made the water clean. Today I tried to make dirty water clean. First I put some cotton wool in a funnel. Then I put tissues over that. Next I poured the water through. Finally the water came out a little bit cleaner. Is your water clean enough to drink? Give a reason for your answer. No, the water still looked brown and dirty. Maybe it has germs in it. 25

30 Teacher Task Consolidation Lead a discussion about whether the water is now clean enough to drink. (NB Do not let your learners drink this water.) Discuss whether it is possible to ever get water entirely clean again after it has been polluted. (In fact, it is very difficult and very expensive.) Bring out the following points: Learners will have managed to remove or filter out only the insoluble solids from the water. There may be other substances dissolved in the water, which we cannot see or remove, such as: salt, chemicals and poisons. There may also be germs in the water that are harmful. These can be made less harmful by adding chemicals such as chlorine (eg swimming pool chemicals or a drop of bleach, or by boiling the water for 15 minutes). Even after boiling the water there may be poisons left in the water, which were produced by the germs. There may also be poisonous chemicals in the water. Many of these poisons are not made safe by boiling or bleaching. 26

31 8 Key concepts g Sewage is water that carries away the waste from our toilets and drains. g People (municipalities) have to make sewage water and drain water clean again before it can go back to the river. g Sewage water is cleaned (or purified) at a sewage treatment works where it is allowed to settle and then it is filtered. Making sewage water clean again Teacher Task Diagram of a sewage treatment process Introduce and explain Introduce the term sewage and explain what it means. Sewage water is the water that comes from our toilets after we have flushed them. It is also the water from our drains. Tell your learners that these days in cities and towns, most of the sewage water is made clean again so that it can be put back into the river. The sewage pipes and drainpipes take the dirty water to the sewage farm. This is called a sewage treatment works or a sewage disposal system. There it is purified. The municipality runs the sewage treatment works. Ask your learners: Why do you think the water must go back to the river? Why must the sewage water be made clean again? Provide your learners with this picture of the sewage works (to photocopy, see page 49). A visit to a sewage works is useful for intermediate phase learners because all the processes are open to view and with good preparation, children can understand what is happening. Waste from toilets, sinks and baths passes to the sewers as well as water run-off from streets and waste from factories. All this is taken to the sewage works, where bacteria play a significant part in its breakdown. 1. Dirty water comes in and is sieved for the first time. SIEVES 2. The water passes through grit channels and the solids drop to the bottom. 3. The solid sludge settles on the bottom. SLUDGE TANKS SLUDGE DIGESTER GRIT CHANNELS 6. The germs are removed from the water and chemicals are added 5. The sludge is digested by bacteria and used for fertiliser FILTER TANK 4. The liquid is filtered and the germs are digested PURIFYING TANK 7. Clean water goes out to the river OUTLET PIPE 27

32 Teacher Task The sewage treatment process Explain the following processes that happen in a sewage treatment plant 1. Dirty water from storm water drains, household drains and toilets comes into the sewage treatment plant. Here it is sieved to remove paper, plastic, leaves and rags from it. 2. Then the water is slowly passed through grit channels. Here, any sand or heavy particles in the water settle to the bottom. The water from the top of the tank still contains lighter particles of organic matter from the toilets and drains. 3. This water passes into the sludge tanks. In these tanks the water is allowed to stand for a longer time. The organic matter now settles to the bottom. It is called sludge and looks like a thick black mud. 4. From the sludge tanks the water passes into the filter tanks. The water still has some small germs in it even though most of the sludge has already been removed. In the filter tanks these germs are filtered out of the water. 5. Meanwhile, the sludge from the sludge tanks is pumped to separate tanks called sludge digesters. Here the black sludge, which looks like mud, is digested and broken down by good bacteria. Then it is pumped out and used for fertilizer. 6. The water that has been filtered flows into the purifying tanks. The remaining germs are removed and chemicals are added to kill of any germs that may be left in the water. 7. The water, which has been treated, is now much cleaner. It is now safe enough to be piped back into the river. Talk through the flow chart of sewage treatment works with your learners and identify the processes. These are: Straining / sieving Settling Filtering Digesting (breaking down the germs + solid substances) Adding chemicals Preparation 1. Ask your learners to build a model of the sewage works. They can do this with a selection of containers such as yogurt cups, ice cream boxes etc. Toilet roll insides can be used for the pipes. The learners will have to be able to explain what the different purification processes are in their sewage works. They will also have to show where each process takes place. 2. Arrange the class so that there are six learners in each group. Two learners must take responsibility for building the model. Two learners must take responsibility for writing the labels and explanations. Two learners must take responsibility for the report back and question session. 3. During the report back session, encourage other learners from each group to ask questions about the sewage treatment system. 4. Develop the assessment criteria with your learners or adapt the ones on page

33 Assessment Task for LO2 Making sewage water clean again The purpose of this assessment task is to recall meaningful information. The learners must use the language that they are fluent in. They must name and describe and explain the features and processes of sewage treatment. (See assessment standards for LO2 grade 5 page 64) 1. Build Look at the diagram on page 48. In your group, discuss how you can build a sewage treatment works using plastic ice cream containers, margarine containers and plastic and cardboard tubes and bottles as shown in the picture. Then build your sewage treatment works. 2. Write Make labels and write an explanation of what is happening to the sewage in each part of your model. 3. Report back You must be able to explain how water would be purified in your model. You must also be able to answer any questions about your model and how water is purified. Questions Do you think that sewage water which goes back into the river after it has been treated, is clean enough to drink? Why do you think so? Do you think it is expensive to purify water? If so, why do you say so? Task card to photocopy on page 48 ASSESSMENT CRITERIA Making a model of a disposal system Assessment task Building the model of a sewage disposal system What we expect from learners The model must: Assessment criteria Have suitable containers which represent the different tanks. Have sieves for the water to pass through the pipes. The tanks must be connected in the correct order. Fit together when connected. Include any other details which relate to water purification. Make labels and write to explain how the water is purified Report back and answering questions about water putification The labels must: Identify correctly the processes that happen at the different tanks, eg sieving, settling, filtering, adding chemicals. Explain how the dirty water is made cleaner during each process. The report back and answers must: Show understanding of the processes that are used in water purification eg sieving, settling, filtering, adding chemicals. Show understanding of the different stages represented by the model. Contain the correct key words for the different processes. Must be delivered in a clear and confident way. 29

34 SIEVES 1 Dirty water comes in and is sieved for the first time. GRIT CHANNELS 2 The water passes through grit channels and the solids drop to the bottom (ice cream boxes) SLUDGE TANKS 3 The sludge settles on the bottom (bottles). FILTER TANKS 4 The liquid is filtered and the germs are digested. SLUDGE DIGESTER 5 The sludge is digested (yoghurt cups). PURIFYING TANKS 6 The germs are removed and chemicals are added. OUTLET PIPE 7 Clean water goes out to the river (pipe at the very end). Model of a water treatment works Model of a water treatment works 30

35 9 How do we get clean drinking water? Key concepts g Long ago people had to fetch their own water. g People had ways to decide whether their water was clean enough to drink. g They had special ways of transporting and storing their water so that it would remain clean. Introduction Long ago, how do you think people made sure that their water was clean enough to drink? river Teacher Task Preparation Prepare for your learners to find out the following: How people long ago found water and kept it clean. How people in rural areas make sure that their water is clean. What can happen if you drink or swim in water that isn t clean. 1. Tell your learners to try to find out at home how people in the past ensured that they had clean water. Afterwards, facilitate a class discussion about what they found out. Listen carefully for points your learners make which provide relevant information about the processes people have used to make water clean. 2. Read Sweet Water /Amanzi Mnandi page Ask learners to draw or find pictures that illustrate some of the points they discussed and read about. 4. Find a space on the classroom wall and put up flashcards of the task card questions on the wall (see page 50). Make sure there is enough space for the children to place their pieces of work under the various headings. Alternatively, if learners have enough information they can make group posters, which you can display on the walls. 31

36 Assessment Task for LO3 Find out how today, and long ago, people made sure their water was clean The purpose of this learning experience is to help learners understand science and technology in the context of history and indigenous knowledge. (See assessment standards for LO3 Grade 5 page 66) 1. Ask and Find Out Find out from someone at home: Long ago, how did people find water and keep it clean? How is this done today? In the past, how did people in rural areas make sure that their water was clean? How is this done today? How did they make sure it was clean enough to drink? How do people do this today? What can happen if you drink or swim in water that isn t clean? Which is better? The old way or the new way? (You can choose either way, but you must be able to give reasons for your choice.) 2. Report back in a class discussion 3. Contribute to a class display. Write and draw what you found out at home. Task card to photocopy on page

37 Suggested writing frame Today and long ago people made sure their water was clean They collected it in a clean place Long ago Today They carried it in clean containers Long ago Today They stored it carefully and kept it clean. Long ago Today Sometimes they had to make it clean by: Long ago Today If you drink dirty water ASSESSMENT CRITERIA Assessment task Assessment criteria Find out how people made sure that their Learners must: water was clean long ago. Contribute relevant information about long ago Find out how people make sure that their methods of keeping water clean. water is clean today. Understand how the long ago methods worked for keeping water clean. Be able to make comparisons between today s methods and long ago methods. Consolidation Discuss with your learners Why is it important to have fresh clean water? How do we know if our water is clean? What happens when people don t have fresh clean water? Why do some people have access to clean water but other people don t? What can our communities do to make sure we have fresh water? 33

38 Suggested work schedule for this sequence of learning experiences PERIOD 1 1. Solids, liquids and gases Teacher introduces the three states of matter Learners write a summary of the properties of solids, liquids and gases PERIOD 2 2. Mixing solids and liquids Teacher introduces every day examples Learners make mixtures with different solids and water Teacher consolidation and explanations PERIOD 3 3. Which solids are soluble and which solids are insoluble? Learners test various substances for solubility Learners draw and write explanations (Start getting learners to collect items for building a model for learning experience 8) PERIOD 4 3. Contd. Learners finish explanations and discuss questions 4. Investigation: Can we make a solid dissolve faster? Teacher introduces the idea of investigations to learners PERIOD 5 4. Contd. Teacher assists learners to develop questions for investigation Assessment task. LO1 Teacher explains the assessment task and criteriaframe Learners think up or choose a question for their investigation. Learners discuss how they will do the investigation PERIOD 6 4. Contd. Assessment task. LO1 contd. Learners finish their planning Teacher checks the plan Learners begin the investigation PERIOD 7 4. Contd. Assessment task. LO1 contd. Learners continue with the investigation Teacher uses one group s results as an example and shows learners how to draw a graph PERIOD 8 4. Contd. Assessment task. LO1 contd. Learners draw their own graphs and then swap results and draw a second graph Learners move from group to group and share results PERIOD 9 4. Contd. Teacher consolidates learnings from the investigation Teacher and learners write summary Note: you will have to schedule time to give learners feedback after you have assessed the investigations PERIOD Can we get the solids back after we have mixed them with water? Teacher explains how to get the solid back from a mixture or solution Learners crystallize the salt from a salt solution Teacher consolidation PERIOD Water is a precious liquid. Discussion about the importance of having clean water Teacher explains why water is so precious Learners discuss the different uses of water and what we add to water Learners prepare to bring samples from home PERIOD contd. Learners add their pollutants to water Learners group discussion about the dirty water PERIOD Making dirty water clean again. Class discussion about a polluted river using pictures Discussion about boys swimming in polluted water Learners start to develop a play or rap or song about how the community can improve the water quality PERIOD Contd. Learners complete their plays and songs Learners perform their songs and plays PERIOD Contd. Learners perform their songs and plays 34

39 PERIOD Contd. Learners make their dirty water clean Teacher sets up equipment to purify water. PERIOD Contd. Learners reflect on the process of making water clean Learners write a report on their method Teacher consolidation PERIOD Contd. Assessment task LO2 contd. Learners continue to build their models Learners prepare their labels explanations and report back PERIOD Contd. Assessment task LO2 contd. Learners present their models and report back PERIOD Contd. Assessment task LO3. Contd. Learners share their information in a class discussion Learners draw and write information which will produce a class poster This work schedule is only a suggestion. It assumes lessons that last for minutes. You will have to adapt it according to your circumstances. PERIOD Making sewage water clean again. Teacher introduces and explains the term sewage Teacher explains the process of sewage treatment using picture Teacher prepares learners for assessment task PERIOD Contd. Assessment task LO2 contd. Learners present their models and report back Note: you will have to schedule time to give learners feedback after you have assessed the models and report backs PERIOD Contd. Assessment task LO3. Contd. Learners add their information to the class poster Note: you will have to schedule time to give learners feedback after you have assessed their contributions to the poster PERIOD Contd. Teacher explains that learners will build a model of a sewage treatment works, using the picture as a guide Assessment task LO2 Teacher explains the task and assessment criteria PERIOD How do we get clean drinking water? Teacher introduces idea that people through the ages made sure that their water was clean Prepare learners to find out by asking at home, using some questions PERIOD Contd. Teacher consolidation PERIOD Contd. Assessment task LO2 contd. Learners begin to build their model PERIOD Contd. Teacher prepares learners for assessment task Assessment task LO3. Teacher explains the task and assessment criteria 35

40 Section 2 Teacher Resources Task Cards to photocopy 1. Task card 1. Mixing solids and liquids Task card 2. Which solids are soluble, and which solids are insoluble in water? Task card 3. Assessment Task for LO1 Investigation: can we make a solid dissolve faster More examples of investigations Task card 4 A. Can we get the solid back from a solution? Task card 4 B. Home Project Task card 5 How does water become polluted? Task card 6 A. What we can do to improve our environment and the water nearby? Task card 6 B. Making polluted water clean again Task card 7. Assesment Task for LO2 Making sewage water clean again Picture of sewage treatment process Task card 8. Assessment Task for LO3 How did people today and long ago make sure that their water was clean? Sweet water/amanzi Amnandi Pictures and diagrams to photocopy Water pollution Cleaning rivers 36

41 LEARNER TASK CARD 1 TASK CARDS TO PHOTOCOPY Mixing solids and liquids Mixing solids and liquids to find out what happens Mix together Mix together 1 medicine spoon of sand 1 medicine spoon of salt 100ml 100ml 100ml of water 100ml of water Draw and label to show what happened Draw and label to show what happened. The sand has not dissolved in the water. The salt has dissolved in the water. We say that the sand is We say that the salt is 37

42 LEARNER TASK CARD 2 TASK CARDS TO PHOTOCOPY Which solids are soluble and which solids are insoluble in water? A. Bring some solids from home and test them to see if they are soluble or insoluble in water. B. Take water and different solids and mix them. Then complete the table. Mix Does the solid Does the solid Can the solid Is the solid Do we have a 5ml Solid + 100ml disappear in settle to the be separated soluble or solution here? water the water? bottom after by the filter insoluble? some time? paper? 5 ml Flour + 100ml water 5 ml Epsom salts ml water 5 ml Bicarbonate of soda ml water 5 ml Maizena ml water C. Draw and write to explain how you can tell whether a solid is soluble. Then draw and write to explain how you can tell when a solid is insoluble. Use some of the words in the table above to help you. What things must you look for to decide if the solid is soluble in water? What things must you look for to decide if the solid is not soluble? D. Questions Discuss these questions in your group. 1. Why did we use the same amount of solid and water every time? 2. Does the amount of solid and water we use make a difference? 3. What would happen if we kept adding more and more of the solid to the solution? 4. Could we get the solid back again after it has dissolved? 38

43 LEARNER TASK CARD 3 TASK CARDS TO PHOTOCOPY Learner task card 3 Assessment Task for LO1 The purpose of this assessment task is to: Plan an investigation by suggesting things that could be investigated Carry out an investigation involving a small number of steps Report back about what you did and what you found out (See the assessment standards for LO1, grade 5 page 63) Investigation: Can we make a solid dissolve faster? Before you start the investigation: Choose or help to think up a question to start your investigation. Discuss how you will set up the investigation. Then do the investigation. 1. Write down the question you are investigating. Question: Which will make sugar dissolve faster: Fridge water? Tap water? Hot water? 2. Draw and label how you set up the apparatus. 39

44 LEARNER TASK CARD 3 (CONT) TASK CARDS TO PHOTOCOPY 3. Record the time it takes for the sugar to dissolve. Do not stir the mixture. 4. Record your observations on the recording sheet: Amount of sugar Amount of water Temperature of the water Time taken for sugar to dissolve 5. Draw a graph of your results (remember to write a heading and label the axes). 6. Share with another group. Explain to them what you did and what you found out. 7. Exchange your results with another group who investigated a different question. 8. Draw a graph of their results. Discuss: What did you learn from them? 40

45 Examples of Investigations EXAMPLE 1 Question: Which will dissolve faster: 1 spoons of sugar? 2 spoons of sugar? 3 spoons of sugar? 1. Set up the investigation like this: 1 spoon sugar 2 spoons sugar 3 spoons sugar 100ml tap water 100ml tap water 100ml tap water 2. Do not stir the mixture. 3. Record the time it takes for the sugar to dissolve. 4. Example of the recording sheet: Amount of sugar Amount of water Time taken for sugar to dissolve 41

46 EXAMPLES OF INVESTIGATION TASK CARDS TO PHOTOCOPY 5. Example of the graph y 16 Graph to show the time it takes to dissolve 1 spoon, 2 spoons and 3 spoons of sugar 14 Time (in minutes) spoons 4 spoons 6 spoons x Note: We used the same amount of tap water and the bottles were the same size. This ensured that we could make a fair comparison between the different amounts of sugar and how quickly it dissolved. EXAMPLE 2 Question: Which will make sugar dissolve faster: stirring it 10 times? stirring it 20 times? stirring it 30 times? 1. Set up the investigation like this: 10 stirs 20 stirs 30 stirs 1 spoon sugar 1 spoon sugar 1 spoon sugar 100ml tap water 100ml tap water 100ml tap water 42

47 EXAMPLES OF INVESTIGATION TASK CARDS TO PHOTOCOPY 1. Record the time it takes for the sugar to dissolve 2. Example of the recording sheet: Amount of sugar Amount of water Number of times Time taken for sugar to we stirred dissolve 3. Example of the graph y 4 3 Graph to show the time it takes for the sugar to dissolve when we stir the solution. Time (in minutes) stirs 20 stirs 30 stirs x Number of stirs Note: We used the same amount of tap water and sugar and the bottles were the same size. This ensured that we could make a fair comparison between the number of times we stirred and how quickly the sugar dissolved. 43

48 LEARNER TASK CARD 4 TASK CARDS TO PHOTOCOPY Can we get the solids back after mixing them with water? A Can we get the solid back from a solution? 1. Boil a small amount of salty water until the salt has crystallised. 2. Pour a small amount of salty water in a saucer or lid and place it in a warm dry place. 3. Make a labeled drawing to explain what happened to the salty water. Use these words to help you: evaporate, crystallize, boil Questions Discuss these questions in your group. When you boiled the salty water: What happened to the water? Where did it go? What happened to the salt? Do you think you could get the water back from a solution? How would you do this? B Home Project Looking for examples of settling, decanting, filtering (sieving), crystallizing and evaporating in our daily lives 1. Look at home to find examples of the ways we do settling, decanting, filtering (sieving), crystallizing and evaporating in our daily lives. 2. Draw and write about how we make use of decanting, filtering (sieving), crystallising and evaporating around our homes. 3. Discuss: Did you find examples of all the processes at home? Which ones were difficult to find? Why? 44

49 LEARNER TASK CARD 5 TASK CARDS TO PHOTOCOPY How does water become polluted? Group work 1. Look at home and find all the things that you add to water when you are washing, cleaning and cooking. 2. Bring a small sample of each substance to school. 3. Show and tell to your group what you have brought. 4. Take a bottle or some container that has a lid. Add clean water to it. 5. Now mix all the things you brought from home into the water. 6. Also add some dead leaves and grass and some soil. Discuss In your group, discuss these questions. What does your water look like now? Would you drink this water or wash in it now? Which of the things that you added to the water have dissolved? Which of the things that you added to the water did not dissolve? When you pour this water down the drain, where will it go? What will happen to the substances in the water? Where will they go? How can we make the water clean again? 45

50 LEARNER TASK CARD 6 TASK CARDS TO PHOTOCOPY A. Improving the environment A What we can do to improve our environment and the water nearby? Make up a play, or a story, or a rap song about what happened to the boys who swam in the river and how the people cleaned up the river. What would happen if one of them drank some of the water? What did the community do to make this a safer place to play? What did the people do to make the water cleaner? 46

51 LEARNER TASK CARD 6 TASK CARDS TO PHOTOCOPY B. Making polluted water clean again 1. Group task Use anything on the table to make the water clean again. Funnel Toilet paper Cut-off cooldrink bottle Dirty water Gauze Filter paper Baby food jar Cotton wool Empty bottle 2. Draw and tell a story with pictures, a rap song or a report to show how you made the water clean. 3. Questions to discuss Did you manage to make your water clean again? Was it completely clean and pure? Was it clean enough to drink? Explain why you think so? 3. Write to explain how you made the water clean. Today First Then Next Finally Is your water clean enough to drink? Give a reason for your answer

52 LEARNER TASK CARD 7 TASK CARDS TO PHOTOCOPY Assessment Task for LO2 Making sewage water clean again The purpose of this assessment task is to recall meaningful information. The learners must use the language that they are fluent in. They must name and describe and explain the features and processes of sewage treatment. (See assessment standards for LO2 grade 5, page 64) 1. Build Look at the diagram below. In your group, discuss how you can build a sewage treatment works using plastic ice cream containers, margarine containers and plastic and cardboard tubes and bottles as shown in the picture. Then build your sewage treatment works. 2. Write Make labels and write an explanation of what is happening to the sewage in each part of your model. 3. Report back You must be able to explain how water would be purified in your model. You must also be able answer any questions about your model and how water is purified. Questions Do you think that sewage water which goes back into the river after it has been treated, is clean enough to drink? Why do you think so? Do you think it is expensive to purify water? if so, why?

53 1. Dirty water comes in and is sieved for the first time. SIEVES DIGESTER 5. The sludge is digested by bacteria and used for fertiliser 2. The water passes through grit channels and the solids drop to the bottom. 3. The solid sludge settles on the bottom. SLUDGE TANKS GRIT CHANNELS 6. The germs are removed from the water and chemicals are added FILTER TANK 4. The liquid is filtered and the germs are digested 7. Clean water goes PURIFYING out to the river TANK OUTLET PIPE 49

54 LEARNER TASK CARD 8 TASK CARDS TO PHOTOCOPY Learner Assessment task for LO3 Find out how today, and long ago, people made sure their water was clean The purpose of this assessment task is to help learners understand science and technology in the context of history and indigenous knowledge. (See page 66 for assessment standards for LO3 Grade 5) 1. Ask and Find Out Find out from someone at home, or read Sweet water/ Amanzi Amnandi on page 51 Long ago, how did people find water and keep it clean? How is this done today? In the past, how did people in rural areas make sure that their water was clean? How is this done today? How did they make sure it was clean enough to drink? How do people do this today? What can happen if you drink or swim in water that isn t clean? Which is better? The old way or the new way? (You can choose either way, but you must be able to give reasons for your choice.) 2. Report back in a class discussion. 3. Contribute to a class display by writing and drawing about what you found out at home. 50

55 Sweet Water / Amanzi Amnandi Sweet Water and early Nguni people The early peoples of southern Africa had commonsense ways of collecting and storing sweet water, not unlike early humans in other parts of the world. This passage looks at Nguni water collection practices. (Comments and scientific observations are in brackets so that readers might see the practical wisdom behind some water collection myths and techniques of the past.) Before the time of the Zulu King Shaka, sweet water was called amanzi amnandi. Shaka s mother was called Nandi and it is said that because it was not considered respectful to use the queen mother s name in this way, Shaka referred to sweet water as amanzi amtoti. (This is how the town of Amanzimtoti south of Durban got its name.) Today both terms are used and many people of Nguni origin will sniff, smile and hold up sweet water collected from a river, spring or well for their household needs. (Water quality scientists today still have people smell and taste household water. Human senses give a refined indication of whether water is good and clean and fresh.) Amanzi Amnandi nabantu basendulo Abantu basendulo babenezindlela zabo ezithile ababezisebenzisa uma bekha amanzi emfuleni. Izindlela zazehlukahlukana ngokwezizwe. Amanzi okuphuza nawokupheka ayebizwa ngokuthi amanzi amnandi. Ngokwesiko lokuhloniphisa kwathi ngesikhathi senkosi ushaka, amanzi amnandi abizwa ngamanzi amtoti, kuhlonishwa unina wenkosi, unandi. Emandulo amanzi ayekhiwa ezindaweni lapho abantu babewezwa khona amanzi ekhala nasematsheni. Babewakha esiphethwini lapho ayehlanzekile khona emahle. Izinguba zaziwashwa emfuleni nezinkomo futhi zaziphuza khona. Lapho kwakukhiwa khona amanzi kwakuphenduka kube indawo lapho kuhlanganela khona izintombi nezinsizwa. Izinsizwa zazilinda osebeni lomfula zihuba ingoma zidlalisela ezintombini uma zizokha amanzi. Izintombi zaziza emfuleni zishaya kancane zihubela phansi sezinanela ukuhashwa yizinsizwa. Kwakujabulisa ukukha amanzi ngoba babazi ukuthi kwakungenzeka bafice izinsizwa ezizokweshela. Ngalesikhathi kuhlangenwe lapho 51

56 52 Historically water was usually collected in areas where people could hear it running over stones or dripping down rocks. (Well oxygenated water supports natural biological cleansing processes.) If a spring was for human use, it was protected by a circle of rocks with a small outlet. Cattle drank elsewhere. An area nearby was cleared and the site soon became a meeting place for young people. Young men would hang around these water collection sites, playing musical instruments and admiring the maidens who came to collect water. The girls would saunter along slowly and gracefully, singing and flirting. Water collecting was rarely seen as a tiring or boring chore because of the prospect of courtship! Protecting the source of water A water source would always be approached with care so as not to frighten crabs and other small water animals. When disturbed, their movement would stir up sediments and the collector would have to wait for the silt to settle. The surface film was brushed aside for sweet water to be collected. (Sediments and surface films have higher bacteria numbers than the middle waters of pools and rivers. Today scientists take water samples below the surface film taking care not to suck up sediments. In this way scientists can get consistent and reliable measures of bacterial contamination.) Collecting water and keeping it clean Clay pots were filled with water and covered with a collecting bowl, a piece of skin or a mat made from incema (juncus kraussi) grass. The water would thus stay cool and fresh. (Water evaporating through the sides of a porous clay pot cooled the contents. Most water bacteria cannot reproduce in cool, dark conditions. Some micro-organisms envelop themselves in calcium secretion in the pores of clay pots. Scientists spoken to were uncertain about detail of these issues but it is of note that, in earlier times, great care was taken to scour out a calcium like scale in water pots. Also of note musical instrument babeqiniseka kakhulu ukuthi abazibangeli umsindo izilwanyana zasemanzini, hleze zethuke ziyaluze kudungeke amanzi. Uma amanzi esedungekile kwakufanele ukuthi lowo ozokha awalinde isikhashana ukuze acwebe. Ngaphaqmbi kokuthi umuntu awakhe amanzi ayephebezwa ngogqoko ukuze akhe amanzi amahle. Amanzi ayekhiwa agcwaliswe izimbiza ambozwe ngogqoko. Ayethi uma ebekwe lapho agcineke emnandi futhi ebanda. Ayemaningi amasiko ayegcinwa nezinkolelo ezazibakhona mayelana namanzi. Kwakunenkolelo yokuthi uma umuntu echamela emanzini noma ebhukuda uzoshintsha ubulili bakhe. Izingane zazixwayiswa kakhulu ngalokhu. Abantu babengokholelwa ukuthi lapho kukhona amaxoxo amanzi akhona angaba mnandi. Amaxoxo ayedliwa uthekwane. Kwakusabisa ukukha amanzi ubukwa uthekwane kanti futhi kwakungafanele ukuthi uwubulale ngoba kwakuthiwa uma ubulala uthekwane noma untshontsha iqanda lawo umuzi wakini uzosha Amanzi babengawakhi uma izulu linethile ngoba amanzi ayedungekile abanye babedlulisa izinsuku ezine ngaphambi kokukha amanzi emva kwezimvula ukuze bawathole esecwebile. Kukhona izitsha ezazibekwa uma kunetha izulu kukhongozelwa amanzi, ayephuzwa noma kuphekwe ngawo ngoba ayeba mahle.

57 is that when the grass lids and head rings for carrying pots became old they were simply thrown away and new ones were woven. Discarded lids did not pollute the river like today s bottle tops and plastic waste.) There were many others customs ad traditional practices surrounding water. Children were warned that urinating in a river would change them to the opposite sex! (This myth was probably sufficiently frightening to prevent people urinating in streams. This would have limited a disease like bilharazia. The bilharzia parasite is passed on from human urine and feaces to small water snails. From these its life cycle takes the diseases back to people through river water.) Traditional myths and warnings Nguni water collectors say that where there are frogs one does not find sweet water. Frogs are eaten by hammerkops (uthekwane, the lightning bird ) and the prospects of collecting water while being watched by a witch-bird must have been terrifying in earlier times when spirits, myth and mystery had a more central place in everyday social life. Children were told that if they killed this bird or stole its eggs their homes would go up in flames. (Where there are frogs one will usually find snakes. Both animals are feared by many people today, not least children told Nguni myths of witches and lightning to fill the heart with terror. Today, scientific tests suggest that many frog species need sweet water if they are to live and reproduce successfully. There must be some doubt about the Nguni suggestion that frogs are an indication of water that is not fit for human consumption.) It was also said that it was not advisable to collect water from a river after heavy rain at the start of annual rainy season. Indigenous commonsense told people to put out to collect rain-water. River water would again be collected four days after the rains stopped and the water had cleared. (Heavy rains wash human and animal wastes into rivers. There is thus a rapid increase in faecal bacteria and disease. In KwaZulu-Natal health workers have to warn rural people not to collect river water after heavy rains as few remember an earlier Nguni practice of not collecting rain-water for four days.) Learning about historical water collection and storage practices can develop a respect for early people and might also help our understanding of water quality issues. thanks to share-net for the use of this material tel

58 A. Many rivers in the world are polluted. Can you see what is happening to this river? 54

59 This picture is taken from Water in our World, a READ Big Book. Water pollution occurs when people dump waste, chemicals, metals and oil into water. Polluted water can look dirty. smell bad, and contain germs or chemicals that cause disease. 55

60 B. What was done to save this river? 56

61 This picture is taken from Water in our World, a READ Big Book. We need to look after our riverbank vegetation. The roots of plants and grass stop soil erosion. Some plants clean water and slow down flood water. 57

62 Section 3 Extracts from the National Curriculum Statement for Natural Sciences Grades R-9 1. Core knowledge and concepts for Matter and Materials (NCS) Outcomes and assessment standards (NCS)

63 Revised National Curriculum Statements Grades R 9 (Schools) Matter and Materials The paragraphs below have been extracted from the NCS policy documents. We have numbered each paragraph and supplied a heading for each paragraph. This makes the paragraphs easier to work with.the paragraphs describe the knowledge and concepts the learners must know. CORE KNOWLEDGE AND CONCEPTS IN MATTER AND MATERIALS Properties and Uses of Materials Unifying statement: We can classify materials by their properties, in order to establish types and patterns. Properties determine the selection of materials for particular uses. Structure, Reactions and Changes of Materials Unifying statement: We can modify materials in ways we choose, through our understanding of their sub-structure. Foundation Phase 1. Sorting materials according to their different properties Materials have different properties such as texture, colour, strength and heaviness, and can be classified by these properties. We make things with materials which have the properties we want. 2. Mixing different substances Substances can be mixed and sometimes changes can be seen, such as the dissolving of a solid, or new colours when food colourings/paints are mixed. Intermediate Phase 1. Boiling and melting points of different substances Pure substances have melting temperatures and boiling temperatures which are characteristic for each substance, and help us to identify the substance. 2. Materials, their properties and classifying them Materials are evaluated and classified by their properties (such as hardness, flexibility, thermal conductivity or insulation, electrical conductivity or insulation whether they can be magnetised, solubility and rusting). 3. Metals, ceramics, polymers and composite materials Major classes of materials are metals, ceramics (including glasses) and polymers (including plastics and fibres). Composite materials combine the properties of two or more materials. 4. Temporary and permanent changes to materials Some changes to materials are temporary but other changes are permanent. 5. Changes brought about by heating Substances change when they receive or lose energy as heat. These changes include contraction and expansion, melting, evaporation, condensation and solidification. (Links with Energy and Change) 6. Dissolving-factors that affect the speed of dissolving The dissolving of a substance in a solvent depends on variables which affect the rate of dissolving. 60

64 Properties and Uses of Materials Structure, Reactions and Changes of Materials Senior Phase 1. Different states of matter and their properties Substances in different states ( phases ) have distinct properties such as crystalline structures, or compressibility/incompressibility, or tendency to diffuse. 2. Absorption and radiation by different surfaces Dark-coloured surfaces get hotter than light-coloured surfaces when exposed to radiating sources of energy like the Sun. Darkcoloured objects radiate their energy as heat more readily than shiny light-coloured objects. (Links with Energy and Change) 3. Magnetism and electrical charging Some materials are magnetised by electric currents or magnets. Some materials can be electrically changed by rubbing them with a different material. (Links with Energy and Change) 4. Conductors and resistors Some conductors and circuit components reduce the current in an electric circuit to a significant extent and are called resistors. Resistors can be selected or designed to control currents. 5. Separating and purifying mixtures A pure substance cannot be separated into different substances while a mixture can be separated usually by physical means. Differences in properties can be used to separate mixtures of different substances (by methods such as filtration, distillation, evaporation, chromatography or magnetism). (Links with Matter and Materials) 6. Oxygen, carbon dioxide and hydrogen properties reactions and commercial uses Specific gases may be separated from the air or produced in reactions, and have many uses in industry and other sectors of the economy. Oxygen, hydrogen and carbon dioxide have characteristic properties and reactions by which we can identify them. 7. Extraction of raw materials Extracting useful materials from raw materials depends on chemical reactions and methods of separation. 8. Processing and producing raw materials effect on the environment Raw materials, from which processed materials are made, must be mined, grown or imported from other countries. Raw materials that are mined are non-renewable and mining has environmental costs. Growing raw materials involves choices about the use of arable land and water catchment areas 9. Particle model of matter A particle model of matter can explain physical changes of substances such as melting, evaporation, condensation, solidification, diffusion and heating by conduction. 10. Acids and bases, reaction of acids Many household substances are acidic or basic. Indicators are substances that react with acids and soluble bases to produce products that have distinctive colours. Acids and bases neutralise one another to form salts. Acids have characteristic reactions with metals, metal oxides, hydroxides and carbonates. 11. Energy in chemical reactions Many chemical reactions need some energy to get started; many chemical reactions give off energy as they happen. 12. Atoms, elements and compounds Elements are made of just one kind of atom, whereas compounds are made of two or more kinds of atoms in fixed proportions. Elements may react to form compounds, and compounds may be decomposed into their elements. Energy input is needed to break a compound into its elements, whereas energy is given out when elements react to form a compound. 13. Reactions with Oxygen Oxygen has characteristic reactions with metals and non-metals, forming oxides. Some of these oxides dissolve in water to form acidic or alkaline solutions. Some metals react more readily with oxygen than other metals. Corrosion of iron is an economically important reaction which can be prevented through an understanding of the reactions between iron, water and oxygen. 14. Cellular Respiration The reaction of oxygen with food releases energy in the cells of living things. (Links with Life and Living) 61

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