Science and Elementary Technology

Introduction

Water is important in our daily life, we cannot do without it. It is used for domestic, industrial, hygiene and other purposes. It is necessary for all of us to ensure that water sources are not polluted.

Look at the following pictures.

Describe each picture above.
Predict what you are going to learn.

8.1: Importance of water

Activity 8.1: Identifying the Importance of water

(i) Identify the uses of water shown in the pictures below.

(ii) Discuss how water is important in the uses identified above.
(iii) Identify other uses of water not shown in the pictures above.

We use water for different purposes.

1. As human food

                                                  Fig. 8.1: Water as human food.

2. I n sanitation
Sanitation refers to the cleanliness of our body, clothes and our surrounding.
The uses of water for sanitation include:

                                                     Fig. 8.2: Using water for sanitation.

3. In farming
The uses of water in farming are as follows:

(a) Watering plants
• Plants obtain most of their water from rain.
During which weather is watering of plants done?
• Plants on a small piece of land can be watered using a watering can.

Huge plantations on many acres of land are watered using sprinklers or by drip irrigation.

(b) Water for animals
• Animals should be provided with plenty of water to drink after they feed.
• All animals should be given clean water.

Name 3 places where animals are watered.

(c) Cleaning tools and farm structures
We use water for cleaning animal houses, stores, farm tools and animal feeding equipment.
(i) Name two animal houses that can be cleaned using water.
(ii) Name two feeding tools that can be cleaned using water.

(d) Mixing farm chemicals
• Farm chemicals are mixed with water and sprayed on the animals to kill the parasites.
• Some chemicals can also be sprayed on plants to kill plant pests.

4. In industry

Most of the things that we use are made in factories.
Things that are made in the factories are called products.

Practice Activity 8.1

1. Match the uses of water shown below with their correct use.

2. Look at the following pictures.

(a) Which picture shows the most economical way of using water?
(b) Explain your choice.

8.2: Sources of water

What to do:
(i) Your teacher will take you for a field visit to observe sources of water around your school.
Note: Do not go near rivers, dams or lakes (water sources) without the help of your teacher or parent. You can drown in water.

(ii) When back at school write down the common sources of water in your District.
(iii) Using Browse Activity on your XO laptop or books in the school library find out about other sources of water that are not found in your District.
(iv) Present your findings to other members of your class.

Where do you get water for use at home?
Where does your desk mate's family get their water from?
A place where we get water from is called a source of water.
We can get water from many sources. Water is obtained from:
1. Natural sources of water.
2. Man-made sources of water.

1. Natural sources of water

Activity 8.3: Identifying natural water sources

(i) Look at the following pictures.

(ii) Name the water sources labelled a, b, c and d.
(iii) Name other water sources.

Human beings do not make these water sources.
Examples include rain rivers, streams, lakes, oceans, seas, and springs.

2. Man-made sources

Activity 8.4: Identifying man-made water sources

Identify the following man made sources of water.

These are sources of water that are made by human beings.
They include dams, wells and canals.

                           Point-check!

• Rain is the main source of water.
• We should not throw dirty things into water sources. They make the water dirty.
• Dirty water can cause diseases.

8.3: Properties of water

Properties are also called characteristics. Only properties of pure water are considered in this unit.

Activity 8.5: Investigating properties of water

Materials Needed:
• Water in a container         • A transparent glass
• Lids                                   • Salt
What to do:
(i) Put clean boiled water in a transparent glass.
(ii) Hold the glass in your hands and do the following:
     • Look at the water. What colour is it?
     • Pour some water in a lid and smell it. Does it have a smell?
     • Drink some of the water. How does it taste?
     • Put a little salt in the water and stir it for some time. What happens?
(iii) Write down the properties you have investigated above.

Pure water is water that does not contain contaminants such as mud and dissolved salts. Pure water is obtained by distillation.
1. Pure water is colourless.
2. Pure water is odourless (has no smell).
3. Water is tasteless.
4. Water is a good solvent.
5. Pure water has a melting point of 0 °C.
6. Pure water has a boiling point of 100 °C.

8.4: Rain Water

What happens to water sources like rivers and streams when there is no rain?
Rain is the main source of water. Rain water fills oceans, lakes and rivers.

Activity 8.6: Investigation to discover a simple water cycle

Materials Needed:
• Source of heat e.g. stove or burner                   • Sauce pan
• Pan containing cold water                                  • Water

What to do:
(i) Turn on your source of heat.
(ii) Pour some water in the Sauce pan. Place the source pan on the source
     of heat.
(iii) Heat the pan until the water boils.
(iv) Wait for the water to boil. How do you know that the water has boiled?
(v) Hold a pan containing water above the source pan.
What do you observe at the bottom of the pan containing cold water?
Why does it happen that way?
(vi) From your discussion, explain how rain forms as shown in the cycle below.

(vii) Discuss the processes: condensation, evaporation and precipitation in your investigation.
(viii) Using your XO Browse Activity research of how the processes; evaporation, transpiration, condensation help in formation of rain. Your can also use books in the school.

A water cycle
• This is continuous process by which water moves from the land to the atmosphere and back to the land again.
• The cycle involves processes such as evaporation, transpiration, condensation and precipitation.

Evaporation
It is change of liquid (water) to vapour (gas).
Transpiration
It is loss of water from plant leaves in form of vapour.
Condensation
It is change of water vapour to liquid water.
Precipitation
Are all forms of water vapour condensed in the sky. They fall down on earth as
rainfall, snow, hail etc.

Effects of rain water

Activity 8.7: Effects of rain water

(i) Look at the following pictures.

From the pictures above, identify:
(a) the beneficial effects of rain water.

(b) the destructive effects of rain water.
(ii) Give 5 activities that cannot be done when there is too much rain.

Positive effects of rain water
• Rain water is used at home for drinking, cooking and cleaning.
• Rain water helps plants to grow.
• Rain water cools the earth.
• When it is dusty, rain water helps to settle the dust.

Negative effects of rain water
• Too much rain water causes floods and land slides.
• Too much rain water causes soil erosion.
• When there is too much rain water, waterborne diseases tend to emerge and spread. Some of        these diseases can cause deaths.
   Name 3 examples of waterborne diseases.
• Too much rain can destroy infrastructure. Infrastructure includes buildings, roads, railway lines        and telephone lines.
• Too much rain disrupts people’s activities.

Practice Activity 8.2

Read the following story.
Jean and Francine are cousins. They are P5 pupils at Bicumbi BoardingSchool. 

Jean lives in Rwamagana while Francine lives in Gicumbi.

When school closed last holiday, their aunt and uncle came to pick them up from school. They were going to spend their holiday in their grandfather’s home at Karongi.

That same day, it rained heavily. This made it difficult for the two cousins to collect their belongings
and pack them in their auntie’s car.

After leaving the school compound they got into a traffic jam. They could not move fast because rainwater had flooded the roads. Traffic policemen were helping the motorists to move.

The traffic jam delayed their journey. It got late so they could not travel to Karongi. Their aunt rented a room in Kigali town for them to spend the night there.

The following day, the weather was warm and they were able to travel comfortably to Karongi. On their way there, they saw healthy plants growing in farms. There were cattle grazing on the green grass that grew by the roadside. They also saw farmers working on their farms. They did not see children going to fetch water from River Nyabarongo as they usually did during sunny weather.

1. (i) Name two positive effects of rain mentioned in the story.
   (ii) Name two negative effects of rain outlined in the story.
2. (i) From the story above, does the writer shows that rain is good or bad? Justify your answer.
    (ii) Do you agree with the writer’s observations concerning rain?
   (iii) If yes give your reasons. If no, give your reasons.
3. Using the Browse Activity on your XO laptop:
    (i) Search the map of Rwanda.
    (ii) Locate Rwamagana, Gicumbi and Karongi from your map.

Methods of protecting the environment from the rainwater

Activity 8.8: Identify ways of protecting the environment from rain water

What you need:
• Sweet potato vines                             • Tree seedlings                     • Hoes
• Machetes                                            • Tape measure

What to do:
(i) Get into three working groups.
(ii) Assign yourselves plots.
(iii) Let one group make terraces, let another group plant sweet potato vines, the last group to plant       tree seedlings.

(iv) Plant trees in areas where they will be allowed to grow.
(v) Take care of your plots in turns. Ensure you water your seedlings and vines. Protect them from         animals like goats and cows.
(vi) Using browse Activity on your XO laptop or books in the library find out other ways of                        protecting  the environment from rain water.
(vii) Present your findings to the other members of your class.

We should protect the environment from rain water.
Some ways of protecting the environment from rain water include planting trees, making terraces, making ditches cultivating anti-erosive plants.

Table 8.1: Examples of methods of protecting the environment from rainwater.

8.5: Water pollutants

Activity 8.9: Observing water pollution

(i) Look at the following pictures.

(ii) Identify and name the water pollutants in the picture above.
(iii) Visit some of the water sources which are affected by pollution.
(iv) Observe the activities taking place around the water sources.
(v) Identify dangers of the polluted water and ways of maintaining the water sources unpolluted.
(vi) Research on ways in which other water sources are polluted. Present your findings to the rest         of the class.

Activity Questions
2. (a) What is water pollution?
    (b) Give 3 examples of water pollutants.
3. When a lot of fertiliser finds its way into water bodies, it pollutes water. What are the dangers of       such polluted water?

The following are major ways in which water is polluted.

1. Human and animal wastes
Human and animal wastes such as faeces and urine pollute water.
These wastes contain germs. When passed in water, they make the water unsafe for drinking and for domestic use.
2. Floods/run-off water
When it rains, rain water flows over the soil. This water becomes muddy. It also carries along solid particles such as pieces of paper and dry grass.
When such water flows into a water source, the water becomes polluted.

3. Waste from factories

3. Waste from factories
Factories make products and produce waste as well.

Most of the waste is dangerous. If the waste is dumped into water they pollute it.
Water polluted by wastes from factories is unsafe for drinking, domestic use and farm use.

4. Oil spillage
Crude oil is transported across seas and oceans in special ships known as oil tankers.
These tankers may accidentally overturn and spill oil into the ocean or sea.
5. Farm chemicals
Examples of farm chemicals include pesticides, herbicides and fertilisers.
Some of these chemicals may dissolve in rain water and be carried to water sources.

8.6: D angers of water pollution

Activity 8.10: Identifying the dangers of water pollution

Materials needed:
• Photographs and cut-outs showing water pollution and its effects.
• Pens and books.
What to do:
(i) Collect cut-outs from newspapers and magazines.

(ii) Look at the following pictures.

(iii) Identify the dangers of water pollution shown in the pictures above.
(iv) Outline other dangers of water pollution from the photographs and cutouts that you have.

Water pollution is dangerous for human beings, plants, animals and soil.
1. D angers of water pollution for human beings
• Polluted water may contain germs and parasite.
• When people drink the polluted water, they take in the germs or parasites.
• These germs spread water borne diseases such as cholera and typhoid.
2. D angers of water pollution for animals
Animals also take in germs and parasites when they drink polluted water.
What are the effects of germs on animals? How can oil spilled on water affect animals?
3. D angers of water pollution for plants
Water that contains excessive fertilisers, pesticides or herbicides can make plants to dry.
What are the other dangers of water pollution to plants?

4. D angers of water pollution for soil
When we use water, which is polluted to grow crops, or for domestic use, we may end up polluting the soil. Polluted soil kills small organisms that live in soil.

8.7: Prevention of water pollution

Activity 8.11: Identifying ways of preventing water pollution

(i) Look at the following pictures.

(a) Describe the activities labelled a, b, c and d.
(b) Which activities will cause water pollution?
(c) Which activities are helping to prevent water pollution?

(ii) Identify different ways of preventing water pollution.
(iii) Write them in your notebooks.
(iv) Talk with your partner about what you have written.

Water pollution can be prevented by stopping or controlling activities that lead to water pollution.
The following are some of the measures that can be taken to prevent water pollution.
1. Practising proper hygiene, for example use of toilets, latrines and urinals.
2. Avoid bathing, watering animals and washing clothes in water sources.
3. Practising farming methods that reduce soil erosion like contour and terrace farming.

4. Avoid draining of industrial and domestic sewage into water sources.
5. Dispose of solid waste properly. Do not dump solid waste in water sources.
6. Clearing accidental oil spills as soon as they happen.
7. Use farm chemicals such as fertilisers, pesticides and herbicides in controlled amounts.

8.8: Water purification methods

Activity 8.12: Experiment on purification of water

Materials needed:
• Source of heat
• Pan or pot with lid
• Sieve or white piece of cloth
• Small containers
• River water or dam water in jerry cans

What to do:

(i) Hold a sieve over a clean pan or pot. If you do not have a sieve, tie a clean piece of cloth around the pan.
(ii) Pour water from a jerry can over the sieve or piece of cloth into a clean pan or pot to filter it. Cover the pan or pot with a lid.
(iii) Light a fire to get heat. Place the pan with filtered water over the heat.
(iv) W(v) Add some water-treating chemical into water in another container.
(vi) Taste the boiled water and the chemical treated water.hen the water has boiled, remove it from        the source of heat. Let the water cool.

(a) (i) Do chemical treated water and boiled water taste the same?
(ii) Name 3 examples of chemicals that can be added to water in your homes to purify it.
(b) Which water would you prefer to drink? Give the reasons for choice of your answer.
(c) Do people in your village purify their drinking water using chemicals or do they boil it?
(d) Why do you think they use the method you have talked about in (c) above?

Water from its sources is not safe for home use. Purified water is safe for drinking and other domestic uses.
Purification of water involves removal of suspended wastes by filtration and germs by boiling or chemical treatment.

1. Boiling water
Boiling is the best method of making water safe for drinking.
The high temperature kills harmful micro-organisms in the water.

2. Filtration of water
Filtration refers to removal of solid wastes from water.
During filtration, dirty water is poured through a filter or sieve into a separate container.

Note: Filtered water is not safe for drinking.

3. Chemical treatment of water (chlorination)

Chemicals treatment of water is widely used in purification of large quantities of water.
The chemicals kill harmful microorganisms in water, making the water safe for drinking and domestic use.
Chemical purification of water is done by water supplying companies. It can also be done in
wells and boreholes.

Fig. 8.12: (a), (b) and (c): Water purification methods.

8.9: Making a water filter

Class Project: Making a water filter

Materials needed:

• A large plastic bottle                          • Clean sand
• Coarse sand                                      • Sharp knife or razor blade
• Beaker                                               • Charcoal
• Clean cotton wool                              • Paper filter
• Small gravel

What to do:
(i) Observe the water filter shown on page 102.
(ii) Following a similar arrangement make a water filter in school.

(iii) Use the filters in your groups to filter muddy water.
The following picture shows a water filter made by a pupil in P5.

Knowing how to make a water filter is important. You can use it to make muddy water clean.
Make a water filter like the one shown above.

8.10: Water storage

Activity 8.13: Role play

The following pictures show activities that you need to role play.

What to do:
(i) Dramatise diarrhoea knockdown as a result of drinking dirty water.
(ii) Play the water relay game as shown in picture (b).

Water storage means, storing water safely for future use. What is the major use of the following containers?

• Water from rainfall can be directed into large tanks and stored for use when there is no rain.
• The water can also be stored in drums, jerry cans, pots, buckets and bottles.
• All stored water needs to be covered to keep away dirt and insects.

How can excess rain water be collected and stored?

• You should put soft drinking water in a portable container and carry it with you.
Why is this important?

Revision Activity 8

1. What is sanitation?
2. Identify the uses of water shown below.

3. Name one chemical that is mixed with water to spray on:
     (a) crops                          (b) animals

4. What is irrigation?
5. Name 3 properties of water.
6. Write down 3 negative effects of water.
7. Look at the following picture.

(a) How is the water being polluted?
(b) How can the pollution shown above be controlled?

8. Identify 5 dangers of water pollution.
9. Outline 3 measures that we can take to prevent water pollution.

10. (a) Name the water purification methods shown below.

      (b) Which method makes water safe for drinking? Explain.
11. You have been provided with muddy water in a container.
     (a) Purify the water by removing observable wastes.
     (b) Make the water safe for drinking.

Word list
1. Read the following words in pairs.
• Recreation                     • Environment                        • Transportation
• Terraces                        • Evaporation                         • Pollutants
• Condensation                • Tank                                    • Precipitation
• Filtration                        • Atmosphere                         • Chlorination
2. Spell 3 words while your friend writes them in his or her notebook. Let
your friend also spell 3 other words as you write them in your notebook.
3. Discuss with your friend the meaning of any 3 words in the word list.
Refer to notes in your textbook.