Primary Science Lessons Year 6
Updated: 2008-07-19
Please send comments to: J.Elfick@uq.edu.au
Suggested answers to the teacher's questions are shown within [square brackets].
Animals Food chains in the forest Protect our turtles Chicken life cycle Pig life cycle Fungi
Bacteria		 Mouldy bread and rotten fruit
Energy Heated liquids expand Water climbs up Pull with pulleys Forces on coins
on a slope		 Floating and
sinking		 Forces of
friction
Human body Shakir strip and malnourished child How far you can see Measure air breathed out Male reproduction organs Female reproduction organs Birth and care
of a baby
Measuring Measure relative humidity Measure air pressure The moon and tides The Southern Cross
Estimating Pendulum tells the time
Plants Trees and shrubs Protect our trees Describe grasses Describe palms Describe ferns and mosses Planting material
Rocks and soils Protect our coral reefs Protect our soils Describe soils Test soil texture Fertilizing soil Chemical fertilizer
Substances Burn candle over water Candle "lava" Electric circuit Electricity conductors Electric torch (flashlight) Magnets
Electromagnets
Table of contenst
6.1 Food chains in the forest
6.2 Protect our turtles
6.3 Chicken life cycle
6.4 Pig life cycle
6.5 Fungi (Singular: Fungus)
6.6 Bacteria (Singular: Bacterium)
6.7 Mouldy bread and rotten fruit
6.8 Heated liquids expand
6.9 Water climbs up
6.10 Pull with pulleys
6.11 Forces on coins on a slope
6.12 Floating and sinking
6.13 Forces of friction
6.14 Shakir strip and malnourished child
6.15 How far you can see?
6.16 Measure air breathed out
6.17 Measure relative humidity
6.18 Measure air pressure
6.19 The moon and tides
6.20 The Southern Cross
6.21 Estimating
6.22 Pendulum tells the time
6.23 Trees and shrubs
6.24 Trees, palms and ferns
6.25 Protect our trees
6.26 Describe grasses
6.27 Describe palms
6.28 Describe ferns and mosses
6.29 Protect our coral reefs
6.30 Protect our soils
6.31 Describe soils
6.32 Test soil texture
6.33 Fertilizing soil
6.34 Chemical fertilizers
6.35 Burn candle over water
6.36 Candle "lava"
6.37 Electric circuit
6.38 Electricity conductors
6.39 Electric torch (flashlight)
6.40 Hanging magnets
6.41 Make electromagnets
6.1 Food chains in the forest
See diagram 9.311: Food chain study
Be able to study animals in the forest and discover food chains.
Use plastic cages.
In this lesson introduce the idea of food chains in the forest and start the children on observing small animals in plastic cages as shown in the figure below. The importance of the food chain is that it teaches children that living things depend on each other. The sign >> means "is eaten by" and shows the direction of the flow of nutrients.
Examples of food chains:
1. leaf >> butterfly >> larva >> lizard
2. Kangaroo grass >> grasshopper >> birds >> round worm parasite
3. Palm beetle >> scorpion >> spider >> bird
4. Dead Casuarina >> fungus >> wood louse >> ant
5. Rotten leaf >> millipede >> toad >> snake >> dog
Before the lesson, prepare plastic cages. Use a plastic drink bottle.
Groups of four
1. Explain the food chains using arrows. Think of some food chains. Use animals in the forest.
2. In the forest telling what eats what is not easy, especially if they are small animals. To enable us to do this you will collect animals and plants from the floor of the forest and study them in plastic cages.
3. Take the children into the forest to collect animals for their cages. Can you see something eating something else? You will need to put different animals together to see what happens to them.
6.1.1 Animals without backbones (Invertebrates)
1. Microscopic single celled animals (Protozoa)
2. Flat worms, parasites in animals (Platyhelminth)
3. Round worms, parasites in animals (Nematode)
4. Ringed worms, earthworms (Annelid)
5. Jointed legged animals (insects, spiders, ticks, centipedes, millipedes (Arthropod)
6. Slugs and snails (Mollusc)
7. Animals with backbones (Vertebrates)
7. 1 Frog, toad (Amphibians)
7. 2 Lizard, tortoise, crocodile (Reptiles)
7. 3 Megapode, parrot (Birds)
7. 4 Flying fox, dog, cat (Mammals)
8. Plants in the forest and grassland
8.1 Green colour in water and wet soil, single celled plants (Algae)
8.2 Moss (Bryophyte)
8.3 Ferns, filmy ferns, bracken, tree ferns, epiphytes (Pteridophyte)
8.4 Pine trees, cycads and palms (Gymnosperms)
8.5 Grasses and shrubs, trees, vines (Flowering plants - Angiosperms)
9. Mould, bracket fungi, mushrooms (Fungi)
10. Aerobic bacteria, need air, anaerobic bacteria, live in mud, both cause rotting. (Bacteria)
6.2 Protect our turtles
See diagram 9.307: Turtle
Be able to explain why you should protect turtles and crocodiles.
Turtles and crocodiles are reptiles. They have a thick skin with scales and lay their eggs on land. In this lesson the teacher should explain that they are interesting animals that are part of your natural heritage. If you killed them with the aid of modern weapons, something that you all own would be lost. There may be a good reason for killing some animals for traditional purposes. Most people are frightened of crocodiles but you should not kill them, just keep away from them.
Both crocodiles and turtles are part of the food chain. In some countries crocodiles are kept in farms for their skins. Crocodiles live in the Laurie Lagoon on Guadalcanal and on the Olu and Malau Islands. You should respect all creatures and let them survive for future generations to study and admire these beautiful creatures. Collect pictures of turtles and crocodiles. Some of these animals are on postage stamps: Green Turtle, Pacific Ridley Turtle, Loggerhead Turtle, Leatherback Turtle, Estuarine Crocodile.
Hawks Bill turtles live near the shore and are easily caught. We seldom eat them but some people kill them to use the shell to make things sold to tourists.
Leatherback turtles are very big and can swim great distances in the open ocean. They are a very old kind of turtle and do not have a bony back shell. They are rare because people eat their eggs when the mother lays them on the land.
Green turtle, Pacific Ridley turtles and Loggerhead turtles are becoming fewer because so many people like to eat them. They catch the mother turtles when they swim to a beach to lay their eggs. In the past people killed only a few turtles for traditional use but now many people use motorboats to catch them and do not respect the old customs. Also large fishing boats from other countries drown turtles when they get caught up in fishing nets.
Turtles cannot lay eggs until they are more than 10 years old. So protecting them now is important or there will be no turtles left for us to watch or eat. What can children do? Do not disturb turtle nests and eggs, let the baby turtles hatch out and get into the sea. Do not catch a turtle when it is moving up the beach to lay eggs. If you see a turtle on a beach, keep it a secret, do not tell everybody, or bad people will kill her before she can lay her eggs. If you are out in a canoe and see a turtle, do not kill it. Tell the teacher where you saw the turtle and what kind it is, then the teacher will give you a prize!
1. Show the pictures of turtles. Ask them if they have seen turtles. What they think about them, should you kill them? Why people kill them.
2. Explain why you should NOT kill them 1. respect for all animals, 2. some kinds of animals should not die out, 3. part of your natural heritage, 4. beautiful creatures that should be admired.
3. Explain why they are in danger of dying out: 1. custom of killing for special occasions or special people. However, some customs are no longer respected. 2. people have motor boats, 4. fishing boats from overseas drown them when the turtles are caught in nets.
4. Explain how they can protect turtles: 1. protect eggs and hatched baby turtles, 2. protect laying mothers, 3. protect turtles at sea.
5. Show pictures of crocodile. What do they think of it? Do they want to kill it? Do they want to protect it?
6. Explain why they should not kill crocodiles: 1. also part of natural heritage, 2. interesting animals, 3. can be farmed.
7. Explain that you should protect it and keep way from it.
Extra Activity:
Turtle sightings.
Encourage the children to report whenever they see these animals. Give a small reward for each sighting.
6.3 Chicken life cycle
See diagram: 50.6.0: Parts of a chicken | See diagram: 2.6:5 Chicken egg
Objective: To explain how the mother hen can make baby chickens.
Discuss the diagram for this lesson with the head teacher before you teach this lesson.
1. Where do baby chickens come from? [Eggs.] Where do the eggs come from? [The mother hen lays them.] What does a hen need to make a baby chicken? [She must mate with a rooster that will put sperm inside her to fertilize her egg.] Then she puts a shell around the egg and lays it.
2. Show the children the diagrams and read the explanations. Most fish and all frogs do not look after their young but chickens always look after their young.
6.4 Pig life cycle
See diagram: 59.01 Pig breeds | See diagram: 59.03: Pig reproduction organs
Be able to explain how the mother pig can make baby pigs.
Discuss the diagrams for this lesson with the head teacher before you teach the lesson.
Where do baby pigs come from? [The mother pig.] Can the mother pig make babies by herself? [No, she needs a father pig to put sperm inside her to fertilize her eggs.] Show them the diagrams and read the explanations: the male pig mates with the female pig. The male sperm fertilizes the female eggs. Each fertilized egg grows into a foetus that gets its food from the mother. The baby pigs are born four months after fertilization. The baby pigs drink their mother's milk and she takes care of them.
Sentence completion: Match the letters 1. 2. 3. 4. with the numbers 1. 2. 3. 4.
The male pig puts the (a) 1. their mother's milk.
The baby pig is born (b) 2. grow inside the mother pig.
The fertilized eggs (c) 3. after four months.
The baby pigs feed on (d) 4. sperm into the female's body
[Answer: 1. 4. 2. 3. 3. 2. 4. (1).]
Extra Activity: From the following diagram explain the parts of the pig. Tell the children to draw a pig and name the parts.
6.5 Fungi (Singular: Fungus)
See diagram 9.201: Mushroom
Be able to describe the characteristics of fungi and state their importance in food chains.
Use Mushrooms, toadstools, mouldy bread
Fungi are not really plants because they are not green and they never get energy from the sun. They get their energy when they digest plants and animals and make them rot. Their method of feeding is more like an animal. Fungi can cause disease and make dead things rot. They can also make useful substances such as penicillin and alcohol. Fungi work with smaller bacteria to decompose plants and animals until they completely rot and return their nutrients to the soil. Imagine if there were no fungi or bacteria, the world would be covered with piles of dead things. If you put your hand in a compost heap, it feels hot, caused by the activity of the fungi and bacteria. Fermenting cocoa also gets hot for the same reason. Most fungi are poisonous so children should wash your hands after touching them. Use some examples of fungi to class.
1. If you have ever broken open some rotten wood, what did you see inside? [White threads and sometimes something growing out of the wood.] This is a fungus that is eating the wood and making it rotten. Use such an example to class.
2. Show the children the different fungi they have collected.
Different kinds of fungi:
1. Toadstools like little umbrellas growing out of the ground or rotten wood. They may be poisonous and glow in the dark, e.g. Calvatia, Filoboletus, Agaricus or Psaliota. 2. Bracken fungi are hard and grow out of the trunk of trees, e.g. Pycnosporus. Some grow on cow dung, e.g. Pilobilus. 3. Some fungi are parasites. They attack living things, e.g. diseases on the human skin and ear, and diseases of cocoa and groundnuts (peanuts) may all be caused by fungi. 4. Yeasts are tiny fungi that cause fermentation. Yeasts change sugar into alcohol. They cause fermentation of cocoa and are used to make beer.
3. Are fungi good or bad? [Fungi that are parasites are bad because they cause disease, all the other fungi are good.]
4. What would happen if there were no fungi to make things rot? [Nutrients would not return to the soil and the world would be covered with dead things.]
6.6 Bacteria (Singular: Bacterium)
See diagram 9.205: Bacteria
Bacteria live like fungi but they are so small you cannot see them except with a microscope but you can see what they do. Dissolve soup powder or cube in a cup of hot water and pour evenly into 3 clean glasses. Add 1 teaspoon of salt to one glass. Add 1 teaspoon of vinegar (acetic acid) to the second glass. Add nothing to the third glass. Cover the glasses and leave them in a warm place for 2 -3 days. The first two glasses remain clear because they contain substances which stop bacteria growing. The liquid in the third glass is cloudy because it contains so many bacteria.
6.7 Mouldy bread and rotten fruit
See diagram 9.196: Rhizopus fungus
Collect waste foods in a sealed glass container see the life of fungi, e.g. cut boiled potato, cut orange, bread. The fungi grow like little threads. They push the ends of the threads into to food to digest it. So they get their food like animals not like plants. If you keep the glass container sealed, you will see water appearing inside the glass for the respiration of the fungi. After a few days the fungi form usually black rounded structures which will burst open to let out tiny spores. The spores are usually carried in the wind to the next food where they grow into a new fungus.
6.8 Heated liquids expand
See diagram 20.1.1: Heated liquids expand
Be able to describe how water expands when heated.
Use A bottle, plastic tube from a ball pen, burners, heating stand, ink to colour the water, cork with a hole through it.
Water expands when heated and contracts when cooled.
1. Give out the materials and tell the children to push the clean ball pen tube through the small hole in the cork.
2. Fill your bottle with coloured water right up to the top. Push the cork gently but firmly into the bottle so that the coloured water is a short distance up the clear tube.
3. Mark on the side of the tube the level of the coloured water. Mark 1.
4. Light your burners. Heat the bottle of coloured water gently on the heating stand. Closely watch the level of the coloured water in the tube. What happens to the level of the water? [The water level rises.] Mark the new level on the side of the tube. Mark 2.
5. Give a reason the water has risen. [It expands when heated.]
6. Take the bottle away from the flame. Watch the level of the water in the tube. What happens to the water level? [The water level falls back to Mark (1).] Give a reason the water level falls. [The water contracts.]
Extra Activity: Show the children a thermometer and show how the mercury level changes when the bulb is placed in hot water and then in cold water. Explain how thermometers are used to measure the air temperature and your body temperature.
6.9 Water climbs up
See diagram 35.6.7:
Be able to show that water can climb up some substances and that water climbs up different substances at different speeds.
Use Strips of newspaper about 2. 5 cm wide and 30 cm long, pieces of thick string about 30 cm long, tin lids, sticky tape, box, ruler, a clock.
The string and paper should be thick, soft and absorbent. If you do not have any suitable string, you can use another kind of paper torn into thin strips. Put a pin on the end of the paper strip to act as a weight. Use a pencil to mark zero above the pin then draw a mark every centimetre. The level of the water should be at the zero. Before the lesson, set up the experiment and watch the water climbing up the paper and string for five minutes. Draw the results on the chalk board. This lets us see practical aspects of capillarity both at home and among living things.
1. Use the sticky tape to stick the strip of paper and the string to the top of the box. The string and paper must hang down so that they just touch the water.
2. Note the time when you put the string and paper in the water. Watch the strips and string. What happens? [The water climbs up the paper and string.] After five minutes tell the children to measure the heights the water has climbed up the water and the string. The heights are measured up from the surface of the water. Write these heights in your table of results.
3. Repeat after five minutes. Repeat up to 30 minutes. Each child should have a chance of measuring.
4. Does the water climb up farther in the string or paper? Check carefully that the children measure from the top surface of the water in the tin lid, at 0 on the rule, to the top of the wet mark.
Extra Activity: Can you think of anything people use at home where the liquid climbs up a string? [Kerosene climbs up the wick in a kerosene lamp.] Dip a long piece of white chalk into ink. Does the ink climb up? [Yes.] Water can also climb up soil from damp places below to dry places above. This helps plants to get water. Show results on a graph.
6.10 Pull with pulleys
See diagram 21.5.0: Types of pulleys
Be able to use pulleys to change the direction of a pull and to move heavy loads.
Use Pieces of string three m long, small pieces of string 40 cm long, pulleys (fixed and movable), bags full of sand or soil (for loads), sticks or strong rulers.
Draw a diagram on the chalk board showing the way the equipment is set up.
1. Tie the load to the string and pull it along the desk top by pulling the string towards them. Can you move the load away from them and still pull the string towards them?
2. Ask successful groups to show how they did it. [This can be done if a pencil is held by another child at the other end of the desk, and the string passed around the pencil.] Give out a pulley to each group.
3. Use the pulley instead of the pencil and try again. Is it to pull with the pencil or with the pulley? [Pulley.] Why? [The pulley wheel can move freely.]
4. Show the children your chalk board diagram then tell them to set up the fixed and moveable pulleys. Check that each group has arranged the pulleys correctly. Each child should take it in turns to hold the neck of the bag between finger and thumb and pull it. Now use the pulleys. Hold the free end of the long string between finger and thumb and pull so that the bag moves from one end of the desk top to the other.
5. Have you found any differences? [It should be easier when the moveable pulleys are used as in the diagram. The pull should be smaller than in the diagram but the distance pulled will be greater.]
Extra Activity:
How can you lift the load above your heads using the string and pulley? Tie your pulleys to a beam across the classroom roof, and to pull up your loads using these pulleys. What could you use a pulley for? [Lifting heavy loads.] A force can be a push or a pull. Forces cause things to move. If you push or pull a small object it can start to move. If you increase the force, it can move faster. In the same way if you want to stop a moving object then you must push or pull it in the opposite direction. If an object is not moving, it does nit mean that there are no forces on it. An object will not move if there are equal and opposite forces acting on it. When a force causes an object to move then work is done. Sometimes work cannot be done because the object is too heavy. The force needed to move it is too big. Machines make work easier for us by decreasing the force needed to do the work. One type of machine is the pulley. The pulley is a grooved wheel. The pulley with a rope or a chain is used to lift heavy objects or to change the direction of a force. A pulley can be used in two ways: a fixed pulley changes the direction of the force and a moveable pulley makes the force needed smaller. If a fixed pulley and a moveable pulley are used together then the direction of the force is changed and the force needed is smaller.
6.11 Forces on coins on a slope
See diagram 14.2.11: Start and stop | See diagram 16.1.0: Forces
Be able to explain why an object can slide down a slope and move another object.
Use Coins of different sizes and a ruler.
This lesson is designed to train children to observe what happens when a force is increased and to introduce the idea of the force of gravity that causes the mass of objects.
1. A force is a push or a pull. A force can make an object start moving, stop or change direction. In this lesson you will use forces to start things moving and find out why they stop moving.
2. Hold down a 20 cent coin with your finger. Move the coin sideways to hit a 10 cent coin. What does the 10 cent coin do? [It starts moving.] Measure how far it moves. Hit the 10 cent coin again but this time hit it harder. Measure the distance the 10 cent coin moved. What difference did you see? [The 10 cent coin moved faster and farther.] How did the 20 cent coin move? [It moved faster the second time.] Why did the 10 cent coin move faster and farther? [The 20 cent coin moved with more force.]
3. Make a slope with a ruler. Slide a 20 cent coin down a slope to hit a 10 cent coin. Note the height of the slope and how far the 10 cent coin moves.
Table of Results
Height of slope
Distance of 10 cent coin
4. What did you notice about the speed of the 20 cent coin when the height of the slope increased? [It moved faster.] What did you notice about the distance the 10 cent coin moved when the height of the slope increased? [It moved farther.] Why did these increases occur? [The force of the 20 cent coin hitting the 10 cent coin increased as the height of the slope increased.]
10. Put a coin on the flat table. Will it move sideways by itself? [No.] What can make it move sideways? [A force.] Pick up a coin. Can it move by itself? [Yes.] Let it go. What happens? [It falls.] Why did it move? Did you make it move with a force? [No.] Did anything push it? [No.] Did anything pull it? [Yes, it was pulled down by the force of gravity.]
5. The earth pulls all things towards it. This pull is called the force of gravity. Hold a coin in your hand. Can you feel a downwards force? [Yes.] What do you call this force? [The mass of the coin.] The mass of the object is the pull down caused by the force of gravity.
6. When you hold a coin in your hand is there a pull down on the coin? [Yes.] Does the coin move down? [No.] Why not? [The coin does not move down because your hand pushes up the coin. The pull down on the coin is equal to the push up by your hand, so the coin does not move.] When an object does not move this is because the pull down is equal to the push up on it.
7. Slide a coin down a slight slope. Why does the coin slide down? [It is pulled down by the force of gravity.] Why does it slide slowly? [There is some push on the coin by the sloping ruler.] Make the slope steeper. Slide the coin down. Why does the coin slide down more quickly? [The coin is pulled down by the force of gravity. The sloping ruler pushes up less on the coin.] Turn the ruler over. What happens to the coin? [It falls very fast.] Why does it fall so fast? [It is pulled down by the force of the gravity, the ruler does not push up on it at all so there is nothing to stop the coin from falling.] An object falls down when the force pushing up on it is less than its mass.
Extra Activity:
1. Repeat the experiment as above but use a 10 cent coin sliding down to hit a 20 cent coin. What do you see? [The distance the 20 cent coin is pushed along the table is less.]
2. Can you explain why a ripe mango or orange fruit drops to the ground from the tree?
Questions: Part A - Force 1. What is a force? [A push or a pull.] 2. Can a force start things moving? [Yes.] 3. Can a force stop things that are moving? [Yes.] 4. Can a force make a moving thing change direction? [Yes.] 5. Which ball hits your hand with the greatest force, the heavy ball or the light ball? [The heavy ball.] 6. The ball thrown high or ball thrown low? [High.] 7. Coconut on a tree. Is there a force pulling down the coconut? [Yes.] 8. What is the force called? [Weight.] 9. Is there a force pushing up? [Yes.] 10. What is pulling it up? [The tree.] 11. Which force is bigger? [If the coconut stays on the tree then, Force down = force up.]
6.12 Floating and sinking 1
Objective: To observe things that float and things that sink.
Collect wood, ball, bottle tops, stones and other objects. You will need also Plasticine (modelling clay) or putty, jars, water, bottles, little stones, a container with water.
Let the children make things float. Are you all the same depth in the water? [No Give each group a bottle or Show how to make a paper boat. Add little stones to the floating bottle or paper boat. Do you stay the same depth in the water? [No, you get deeper until you sink. Give the children things that sink including a lump of Plasticine what happens when things sink? [The water level in the container rises. Make a canoe out of the Plasticine. If the walls are very thin, it will float. What is the difference between the Plasticine sinking and floating? [When it floats the water level in the container is higher, the volume is bigger.
Extra Activity: What other things can be made to sink or float? [Galvanized iron canoe, an iron boat.]
6.12.1 Floating and sinking 2
Be able to explain why an object that sinks in water can be made to float.
Use Plasticine, jar and water.
An object that sinks can be made to float by increasing its volume so that the mass of the object is less than the mass of the water displaced. one mL of water weighs close to one gram. Make the boat by moulding the Plasticine around a small jar. Try out the experiment before the lesson. This will give an idea of the extent to which it can work. This discussion can help in explaining the floating of ships and liners.
1. Half fill a jar with water, mark the level of the water on the side of the jar.
2. Make a piece of Plasticine into the shape of a boat with high sides. Float the boat in the jar of water. What happens to the level of water in the jar? [It goes up.] Why did the level of the water go up? [It was pushed up by the part of the boat under the water.]
3. Now sink the boat. What happens to the level of the water in the jar? [It drops.] What does this new level tell you? [This is the volume of the Plasticine used to make the boat.] Was the volume of the Plasticine greater or less than the volume of the floating boat? [Much less.] What is the mass of the boat?
4. Float the boat again. Add bits of Plasticine so that it floats lower in the water. What has happened to the level of water as the boat floated lower? [It rose.] Why did it rise? [The boat has pushed out more water as it floated lower.] Why did the boat sink down more? [It is heavier or more massive with bits of Plasticine in it.]
5. Add more Plasticine until the boat is just floating. It cannot float any lower without sinking. What is the volume of the boat? [Equal to the volume of the water pushed out.]
6. Find the mass of the water pushed out.
7. Conclusion: An object floats when the weight of the object is less than the weight of the water it pushes out or displaces.
Extra Activity:
1. How does step 7 above explain floating of ships? [The weight of the ships is less than the weight of the water displaced.]
6.13 Forces of friction
See diagram 4.182:
Be able to explain what causes friction and how you can reduce it.
Use three new match boxes, two of them full of sand and the other one full of heavier materials like nails, a heavy book, a piece of string, lead pencils.
You can teach the idea of friction using the previous coin experiment in Stopping and Starting. Remember that friction is both an advantage and a disadvantage. Friction allows us to walk without falling over and to pull a thread with a needle. Smooth car tires have less friction on the road than tires with tread. Which tyre is the safest? Friction is also the cause of wear of the moving parts of engines so you have to reduce friction with lubricants such as motor oil.
1. Rub your dry hands together. What do you feel? [Hands get hot.] Wet your hands and do it again. What do you feel? [Not hot.]
2. Explain that your hot hands are caused by the force of friction. When two things rub over each other there is a force in the opposite direction to the movement called friction. When you wet your hands, they were lubricated with water. The water between the hands reduced the friction. To stop the metal parts of engines rubbing on each other you use oil called lubricating oil.
3. Show the children a matchbox and matchsticks. Where do you strike the match? [Strike on the black part at the side.] Try to strike the match on the smooth part. Why does the match not light? [Because you struck it on the part that is smooth. You must strike it in the black part that is rough where there will be more friction.]
4. Matchbox race
Label the matchboxes full of sand "S" for smooth and "R" for rough. Label the heavy matchbox "H". Do not tell the children what the letter means. Put the three matchboxes in line on the end of the heavy book. "S" is lying on the smooth side. "R" is on its black side. It is lying on its smooth side. Tip up the book. Which matchbox comes first, second and third? Do it often and put the results on the chalk board. Let the children pick up the matchboxes then explain the race using the word friction. Smooth comes first because the force of friction is least between the smooth side and the book, rough comes second because it is sliding on its back rough side so the force of friction is greater. You are the same weight. Heavy comes last because a heavy weight increases the force of friction a lot. You can reduce friction by changing sliding motion to rolling motion. Put a piece of string through a book and roll it along. Now put the book on pencil rollers. What do you feel? [The pull needed is less.]
Extra Activity:
1. Methods of reducing friction The simplest method of reducing friction is to place rollers between the two surfaces. This method is used when boats are launched, or when heavy wooden crates have to be moved. Here linear friction is replaced by rolling friction. Ball bearings are used to reduce friction for revolving shafts. The axle of a bicycle is mounted in ball bearings. The ball race shown is similar to the ball race used in a bicycle. Friction is thus reduced by 1. replacing linear friction with rolling friction, and 2. by using hard surfaces, as hard surfaces have less friction than softer surfaces. Lubrication is the most common method of reducing friction. On a bicycle all moving parts have small holes through which oil is squirted so that the parts that move in contact with one another are covered in oil. On a motor car, grease nipples are provided for the same purpose and grease is forced under pressure through those nipples.
2. How does friction help in increasing or decreasing the speeds of athletes at sports meets?
6.14 Shakir strip and malnourished child
See diagram 9.236: Shakir strip
Be able to discover malnourished small children by measuring their arms with the Shakir strip.
Use The Shakir strip.
People who do not have enough food or do not have the correct amounts of energy food, growth food, and healthy food are said to be malnourished. Malnourishment of young children, especially after weaning, can be very dangerous. They may get sick and die or they cannot learn much when they go to school. It is not easy to tell whether a child is really undernourished or has a temporary sickness. This problem has been solved by the Shakir strip used in many countries. When babies are about one year old, they have much fat under the skin of their arms. When you are five, this fat is not there but there is much more muscle. This means that the circumference of the upper arm is almost the same between the ages of one and five. If you measure the middle of the upper arm of children between the ages of one and five, you can find the malnourished children. Instead of a tape measure you can use a piece of string or a strip of material that does not stretch, e.g. old x-ray film.
1. Children between the ages of one and five should not be malnourished otherwise they may get sick and die. Malnourished children may not learn much when they grow up.
2. Doctors have found a way to tell if children are malnourished by using a marked tape called the Shakir strip. It is one cm wide. The circumference of the upper arm is as follows:
Shakir Strip
Circumference of Upper Arm Colour Zone Health of Child
Greater than 135 cm green zone Healthy child, not malnourished
Between 125 and 135 cm yellow zone Child probably malnourished
Less than 125 cm red zone Child certainly malnourished
3. Cut a strip of paper the length of the page and one cm wide. At six cm from one end mark 0 cm. Then mark it at 12. 5 and 13. 5 cm. Colour 0 to 12. 5 cm red, 12. 5 to 13. 5 cm yellow and more than 13. 5 cm green. Give the children a cardboard toilet roll centre or a thin tube to measure. Are they correct?
4. Take the Shakir strip home and measure the arms of all the children aged one to five. If you find any children in the yellow or red measurement, you should tell the teacher the next day.
Extra Activity: Why may recently weaned children or animals be malnourished? [There is no suitable food for them or mothers do not prepare proper food.]
2. Do a class or community experiment on this for one to five year old children and then record a graph to compare malnutrition rates.
6.14.1 Child with diarrhoea - Shakir test
1. Be able to take care of younger children with diarrhoea by replacing water lost because of dehydration.
(in many areas, diarrhoea is the most common cause of death in small children, and is specially frequent in babies between six months and two years. It is more common and dangerous in children who are malnourished. Bottle fed babies have diarrhoea more often than breast fed babies. Diarrhoea can be prevented by: breast feeding babies for as long as possible, good nutrition and cleanliness. If you are a good teacher, you can teach your children how to care for younger children with diarrhoea. Use sugar, salt, water, spoons, cups.
2. How to give the drink, coconut water or "special drink": Start giving the drink when diarrhoea begins. A child should drink for each time a stool is passed. If the child vomits up the drink, keep giving more. A little of it will stay in the stomach. Give it in sips every two or three minutes. If the child does not want to drink, gently insist that the child tries to drink something. Keep giving the drink every two or three minutes, day and night until the child urinates normally, every two or three hours. Older children and their mother can take turns through the night.
Warning signs: Take the child with diarrhoea to the Health Centre if the child shows any signs of dehydration, cannot drink or will not drink, makes no urine for six hours, has diarrhoea too often so cannot drink one glass per stool, has blood in the stool, diarrhoea lasts more than two days.
3. Diarrhoea means frequent watery stools. Often children with diarrhoea also have vomited and have a swollen belly with cramps. The stools smell different from normal stools (toilet).
4. Children die of diarrhoea usually because their bodies lose too much water. This loss of water is called dehydration. All living things contain much water. For example, if you bring two cut plants to school, and put one in water and the other not, you will see that one will wilt. A baby with diarrhoea loses water like the wilted plant.
5. Signs of dehydration: 5.1 almost no urine that is dark yellow, 5.2 dry mouth, 5.3 sunken tearless eyes, 5.4 sunken soft spot (fontanelle) on top of baby's head, 5.5 skin loses its stretching. If you lift up the skin and you can still see the fold after you let go, the child is dehydrated.
6. The most important part of treatment is to replace the water lost through diarrhoea and vomiting. Medicines are often not very effective but coconut water puts water back into the child. Also children with diarrhoea must be given food, if they can take it, to help their bodies fight the sickness. 5. The Special Drink: Make the Special Drink from sugar, salt and water. Mix: sugar + salt + water. Use one level teaspoon of sugar and add a little salt at the end of the spoon in one glass of water. Before giving the drink taste it, it should be no more salty then tears. Let the children make the Special Drink and taste it.
Extra Activity: Visit a Health Centre to see how children are treated for diarrhoea and dehydration.
6.15 How far you can see?
Be able to test their eyes to find out if they can see things near and far.
Use Various objects, e.g. books, windows, trees
In the human eye the distance between the lens and the screen [the retina.] remains the same whether you try to see things near or far. What changes is the shape of the lens controlled by muscles in your eye.
1. Look outside the classroom at something far away. Hold up one finger 20 cm in front of your eyes but keep looking at the distant object. Can you see the distant object clearly? [Yes.] Can you see your finger clearly? [Not at first.] Can you feel any movement in your eyes? [Yes.] Is the distant object clear now that the finger is clear? [If you keep looking at your finger then the distant object will not be clear.]
2. Hold a printed page at arms length. Bring the book closer and closer until it is just too close to read the letters. Measure the distance from the book to the eyes with a ruler and record it in your notebook. Move the book away from the eyes until it is just too far to read the letters. Measure the distance and record.
3. Compare the distance recorded with other children. Are they all the same? [No, the answers should vary.]
4. Judging distance game
One child of each pair puts a hand over one eye. The other child holds up one finger about 40 cm in front of the partner's eyes. The child with one eye covered has to place the tip of one fingers on top of the finger that the partner is holding up. [This is difficult to do because you need both eyes to judge distances.] Uncover your eyes and try again. [It should be easy for them with both eyes open.] Partners swap places and repeat the activity. What conclusion? [We need both eyes to judge distance correctly.]
6.16 Measure air breathed out
See diagram 20.3.0:
Be able to measure how much air breathed out by displacement or water.
Use Marked jars, each group should have at least three jars, buckets, basins or any pool of water, lengths of rubber hose or hollow pawpaw sticks. Each child will probably need three jars to measure how much air in the lung.
The children take turns using the jars. Do the activity outside because water will be spilt. Take a deep breath. Blow air out slowly into one jar until all the water has been pushed out. Transfer to the next jar and blow more air out until your lungs are empty. You may need a third jar. The volume of the air in this person's lung is 1,000 cm³ + 1,000 cm³ + 200 cm³ = 2,200 cm³. The children will need help adding up how much air in each jar.
1. How can you make air replace water? [We did before by blowing air into upside down jars filled with water.] This time you will measure the volume of the lungs by measuring the volume of water the air pushed out.
2. Use one group to show the rest of the class how to fill the bottles of water, blow into the jar and refill with water. How much air breathed out is about equal to how much air is in the lungs.
3. Let each child to try to find out how much air in the lungs.
4. Draw a table of results on the chalk board. Which child has the largest volume of air in the lungs?
Be careful! Do not let children blow hard and do not make them blow if they feel sick!
6.17 Measure relative humidity
See diagram 37.8.1: Wet and dry bulb hygrometer | 37.8.4 Relative humidity table, depression of the wet bulb
Be able to explain the importance of humidity in your climate.
Use Figures of humidity measurements, thermometer and a piece of cloth.
Humidity is a measure of how much water vapour in the air. More water vapour can be in the air at higher temperatures than at lower temperatures, so if the temperature drops the water vapour will condense as rain. The relative humidity used in weather forecasting is a measure of how much water vapour held in the air compared with the amount it could hold. In the Solomon Islands humidity is always high. It does not change much during the year but it varies during the day. Relative humidity %
Month Time Auki Munda Honiara Kira Kira
June 9 a.m. 91 92 - 87 - 93
June 3 p.m. 77 75 - 70 - 77
Dec. 9 a.m. 85 85 - 83 - 90
Dec. 3 p.m. 75 75 - 73 - 77
At night the relative humidity is always greater then 90%. The lowest relative humidity occurs during the hottest times of the year. Children should understand that the climate of the Solomon Islands is hot and humid whereas in some places such as Western Australia and California it is hot dry. In Honiara there is the biggest change in relative humidity because the winds usually shift from southerly in the early mornings to northerly in the afternoon. You will need a bottle and running water. You can make a wet bulb thermometer with a thermometer and a piece of cloth.
1. Hold a bottle under a running tap and breathe into the bottle. What do you see? [The inside becomes cloudy.] What is inside the bottle? [Water.] Where did it come from? [Our lungs and the air.]
2. What do you see inside the walls of a freezer? [Ice.] Where does the ice come from? [It comes from the water in the air.]
3. Air can hold water in it as a gas. This gas is called water vapour. How much water in the air is called the humidity. The climate of the Solomon Islands is always humid compared with many other countries. The humidity is high because the country is near the equator and so the climate is hot. The winds come from over the sea picking up water.
4. If humidity is high, metal rusts easily, fungus diseases can live in the air and people feel hot because they cannot cool down so much by sweating. So remember that there may be problems with imported machines or seeds if they come from countries where humidity is low.
Extra Activity: Cover the bulb of a thermometer with cloth and dip this in water. The temperature should drop. The greater the drop in temperature the lower the humidity. The instrument used to measure relative humidity is a hygrometer. The hygrometer described in the activity uses two thermometers, a dry bulb thermometer and a wet bulb thermometer. The dry bulb thermometer is simply an ordinary mercury or spirit thermometer used to measure the temperature of the air. The wet bulb thermometer has the bulb is covered with cloth kept moist by means of a cotton wick and a glass of water. Evaporation cools the bulb and makes the reading lower than the dry bulb thermometer. The two thermometers are used in conjunction by means of tables to find relative humidity. The higher the humidity, the greater the difference in temperature between the two thermometers.
6.18 Measure air pressure
See diagram 4.272: Air pressure
Be able to state how atmospheric pressure (air pressure) affects weather.
Use Coins, glasses of water with cardboard lids, drinking straws or tubing.
If you have a simple barometer or aneroid barometer you can use it in the lesson. The average mean sea level pressures for example at Honiara in millibars (mb) are as follows:
June 9 a.m. 1010.7 mb 3 p.m. 100(8) 8 mb
December 9 a.m. 1007. 9 mb 3 p.m. 1006. 2 mb
1. Give each group a coin. Wet one side and then press it on the forehead. Why does the coin not fall down? [The air presses it against the forehead.]
2. Give each group a glass full of water covered with a cardboard lid. Turn it upside down. Why does the water stay in the glass? [The air presses the cardboard against the water.] In which direction does the air press? [The air presses in all directions.]
3. Give each group a straw or tube and a glass of water. Suck on the straw until the water is half way up it. Why does the water go up the tube? [When you suck in some air, the air pressure in the straw becomes less. Then the air pressing on the water in the glass pushes some water up the straw.] Put your first finger over the top of the straw and hold up the straw. Why does the water stay in the straw? [The air is pressing up.]
4. Explain that air pressure can change. Air pressure is greatest at sea level and gets less with height. Air pressure can also change at one place. When the air pressure is fine, the weather will stay fine. When the air pressure is low, rain clouds will come and there will be wet weather. Very low air pressure occurs before a cyclone.
5. Air pressure is measured with a barometer. This is a tube closed at one end. The other end is open in a bowl of mercury. Mercury is a very heavy liquid. When the air pressure is high, the mercury is pushed high up the tube. When the air pressure is low, the mercury is lower in the tube. On a fine day at sea level the atmospheric pressure is 760 mm of mercury.
Extra Activity: Read a barometer every day. Note when is the pressure high and when is the pressure low. Make a table to show some daily records of air pressure at 9.00 a.m.
6.19 The moon and tides
Be able to observe the moon and tides and try to find a connection between their movements.
Use Custom stories and observed movements of the moon.
This activity consists of three parts: custom stories about the moon and tides, movements of tides, movements of the moon. There are many interesting stories about the moon. Some people see a woman weaving baskets in it. Some people think it is a friend of Haley's comet, which reappears every 76 years, called the smoking star. The palolo worm which is a swimming annelid worm, rises to the surface on the second night after the full moon in November. Then they mate and lay their eggs. Try to find out the times for high and low tide and the phase of the moon.
1. When do you get high tides and low tides during the day? [There are two high tides and two low tides each day about 12 hours apart.]
2. Are the heights of the high tide and low tide always the same during the month? [No.]
3. Are the heights of the high tide and low tide the same during the year? [No.]
4. What else changes during the month? [The moon.] How does it change? [First there is a new moon when you can hardly see it then it gets bigger until a full moon, then it gets smaller.] How many days between full moon? [30.] How many days in a month? [About 30.]
5. Can you see any connection between the moon and the tides?
6. Can you remember any custom stories about the moon and the tides?
Extra Activity: Wall chart on the phases of the moon. Rule the chart into squares and number the squares with the dates of the month. Each evening a different child has to look for the moon then draw it on the chart the next day. Wall chart on the tides, tide during the day. Measure the depth of the tide each hour and mark on the wall chart. Measure the highest tide and lowest tide each day and mark on the wall chart.
The Sun-force is about 5 / 11 of the Moon-force on the earth but they can act conjointly. When a high tide occurs on one side of the Earth a high tide occurs on the other side of the Earth. Spring tides are higher than other tides and occur just after new Moon and full Moon when the gravitational attraction of both the SUN and the MOON act in a direct line. Spring tides are nothing to do with the spring season. They "spring up" higher than the other tides. When the Moon is at first quarter or third quarter, the tide is minimum, has the least rise and fall, and is called the neap tides The rise and fall of the neap tides is about half that of the spring tides.
6.20 The Southern Cross
See diagram 36.19.2: Southern Cross constellation
Be able to observe the movement of stars in the Southern Cross constellation.
Use Evening and night observations of the stars in the Southern Cross and custom stories about it.
Make sure you can find the Southern Cross and pointers. When you have done that, you can show the position of this constellation to children who will do their observations at night.
1. Draw the Southern Cross constellation and pointers on the chalk board and show the children in what part of the sky these stars can be seen.
2. Look for these stars that evening. The next day, make sure that you really did see the Southern Cross. Then tell the children to observe it the next evening at three different times: 6:00 p.m., 7:00 p.m. and 8:00 p.m. Draw it and another object such as a tree at these times.
3. The next day, look at their drawings. Do you realize that the Southern Cross and all stars appear to move in a circle to the right? This shows that the earth is turning.
4. Show the children how to find South by extending Gamma, Alpha Crusis X 31/2, then dropping to the earth.
Extra Activity: Do you know any traditional stories about the Southern Cross? Some people said that the Southern Cross is a fishing net suspended on four poles and the pointers are two fishermen. Some people said that the appearance of the Southern Cross in March told them to start planting yams.
6.21 Estimating
See diagram 2.6.21: Estimates
6.21.1 Estimate total number using volume
You will need a jar full of seeds, e.g. bean seeds
1. Fill a matchbox with seeds from your jar.
2. Count the number of seeds in the matchbox. Record the number (N1).
3. Find out how many matchboxes of seeds there are in the jar. Record the number (N2).
4. Multiply the number of seeds in the first matchbox by the number of samples (N1 x N2).
5. Record this estimate in the table.
6.21.2 Estimate total number using areas
1. Draw 10 squares as in the diagram
2. Pour seeds onto the paper to completely cover one square, one seed thick.
3. Count the number of seeds in this square (N1).
4. Continue to add seeds to the squares until you have used all the seeds in the jar. Count how many squares you used. (N2)?
5. Multiply the number of seeds in the first square by the number of squares used (N1 x N2).
6. Record this estimate in the table.
Compare this estimate with the estimate for 1A. Are the estimates similar? Which estimate do you think is best? If you have estimates from different groups in the class calculate the average estimate.
6.21.3 Estimate total number using divided samples
You need 5 glass jars of the same size.
1. The first jar is full of seeds.
2. Pour seeds from the first jar into a second jar. Each jar contains half the seeds. Each jar contains an equal number of seeds.
3. Pour seeds from the second jar into a third jar. The second and third jar contain the same amount of seeds. They now contain a quarter of the original volume of seeds.
4. Repeat this procedure twice. The final set of jars is as in the diagram. The sample is contained in jar number 5. Count the number of seeds in jar number 5. It contains 1/16 of the total. Multiply the number of seeds in jar number 5 by 16.
6. Record this estimate in a table.
7. Count the number of seeds in the first jar by counting out the seeds in piles of ten. Record your actual number in a table. Which of your estimates was closest to the actual number of seeds?
6.21.4 Estimate total number using layers
Use a full box of matches but do not count them. Open the box. Count the number of matches you can see on in the top layer. Count the number of layers in the box. If you assume the same number of matches in each layer, you can estimate the number of matches in the matchbox. Use this method to estimate the number of seeds in the jar. Can you use this method to estimate: 1. The number of bricks used to build your classroom 2. The number of sticks of chalk in a box 3. the number of words on a page of a school textbook?
6.21.5 Estimate lengths using your body
Use a ruler to measure in centimetres these parts of your body: 1. The top joint of your thumb. 2. The length of your forefinger. 3. The span of your hand (see diagram). 4. The distance between the thumb and the nose when your arm is outstretched. This is for measuring cloth or rope. These parts of your body can all be used for measuring short lengths, e.g. the length of your desk, or the height of a plant. Which distance would you use to plant seeds about 15 to 20 cm apart? For distances on the ground you can use the length of your foot, or the length of a stride. Measure the length of a normal walking stride. Use it to estimate the length of a football pitch. Mark out distances of one metre along a straight line. Walk along this line. Make each stride one metre long. Remember what it feels like. Use it to estimate the length of a football pitch. Then measure the football pitch. Which of your two estimates is best?
6.21.6 Estimate heights
Estimate the height of a flag pole or a tree. You need a stick, or a ruler, and a stone.
1. You and your friend should stand on lines at right angles to each other as shown in diagram 1.
2. Hold your ruler in front of you and move either forwards or backwards until it appears to be the same size as the flagpole (diagram 2). The bottom of the ruler should be in line with the bottom of the flagpole. The top of the ruler should be in line with the top.
3. Do not move your hands. Let the ruler turn until it is horizontal (diagram 3). The left end of the ruler is still in line with the base of the flag pole. Ask your friend to put a stone on the ground where it is in line with the end of the ruler.
4. Measure the distance between the stone and the flag pole. This is a good estimate of the height of the pole.
6.21.7 Estimate area of a leaf
The areas of squares and rectangles can be measured so you can use these to estimate other areas, e.g. the area of a leaf.
6.21.8 Estimate area of a mouse
Rectangles of paper could be used to estimate the body area of animals, e.g. The body area of a mouse. Use this method for estimating the area of your skin. You will need lots of newspaper, pins, scissors and a ruler.
6.21.9 Estimate weight
Lift one kilogram. Feel the weight. Lift different things, e.g. bag of potatoes, house brick, bucket of water, school bag, your friend. Can you estimate their weight in kilograms?
Know the feel of these weights: 10 grams - the weight of 4 beer bottle tops 1 kilogram - the weight of 1 litre of water 10 kilograms - the weight of 10 litres of water. Use a balance to estimate the weight of small objects of the same size, e.g. pins and paper-clips.
Useful ways to measure and approximate size
1 teaspoon (the smallest spoon) 4.5 mL
1 dessertspoon (the spoon you eat with) 10 mL
1 teacup (the cup you use with a saucer) 200 mL
1 matchbox volume 25 mL
Area of the top of a matchbox 20 cm2
1 gallon container holds 5 L
1 fluid ounce container holds 30 mL
Human body temperature 37oC (Celsius)
Weights of one matchbox full of fertilizer
Ammonium sulfate (sulfate of ammonia) 26 g
Potassium chloride (muriate of potash) 24 g
Single superphosphate, "super" 22 g
Triple superphosphate, "super" 20 g
Sulfur 20 gm
6.22 Pendulum tells the time
See diagram 15.1.1: Pendulum technical diagram
Be able to observe the effect of changing: the swing, length, and weight of a pendulum on the time taken for each swing.
Use string, a pendulum bob, stop watch or watch with second hand. Set up a pendulum so that you can change the length of the string and weight of the bob.
Set up the pendulum as in the diagram. The distance from the knot to the centre of the bob should be exactly one metre. The time for one complete swing is the time between movements over the arrow in the same direction. Pull the bob a few centimetres to the side then let go. Then try with a big swing. Then try with a shorter swing. Then try with a one metre swing and heavier bob.
The time for a swing is the time for the pendulum bob to go forwards, then backwards to where it started.
Fill in the table, for example:
Length Weight Size of swing Time for one swing
1.0 m 1.0 kg big swing 2 seconds
1.0 m 0.5 kg big swing 2 seconds
1.0 m 0.5 kg small swing 2 seconds
0.5 m 0.5 kg big swing about 14 seconds
0.5 m 0.5 kg small swing about 14 seconds
1.5 m 0.5 kg big swing about 25 seconds
1.5 m 0.5 kg small swing about 25 seconds
Extra Activity: Watch a swinging pendulum very closely. Where does it move fastest? [In the middle of the swing when the bob is passing the arrow.] When does it move slowest? [At the end of each swing when it stops then changes direction.]
6.23 Trees and shrubs
See diagram 9.53.9: Different trees
Be able to identify and describe some trees, shrubs and herbs in the locality.
Use Local examples of herbs, shrubs and trees, plant presses.
The plants you know as trees, shrubs and herbs or bushy plants have the parts of their flowers in fives, leaves shaped like hands with three parts, a tap root, and the trees and shrubs are woody. Trees are tall with usually one main stem. Shrubs are smaller and branch near the ground. Trees include the mango tree, cassia trees, Acacia, Casuarina or she oak and Ngali Nut tree. Shrubs include Euphorbia, Hibiscus, side herbs include most weeds, e.g. Commelina.
1. Explain the difference between trees, shrubs and herbs and show the children some examples. [See the differences above.]
2. Look at a herb. Does it have a stem? [Yes.] What is the shape of the leaf? [Like a hand.] What kind of root does it have? [A tap root and smaller roots.] Does it have flowers? [Yes.]
3. List all the trees, shrubs and herbs you know. They may have to stroll around the area.
4. Some herbs are thin stemmed vines, some are called climbers, e.g. Passion fruit (Granadilla) and Bougainvillaea. Some are creepers, e.g. Basella (Indian Spinach.)
5. Garden Walk
See the trees, shrubs and herbs.
Extra Activity: Display of cut out shapes of trees, shrubs and herbs. Hold a piece of paper up and draw the shape of the tree on it. Cut it out and stick it on the display board. Can you tell a tree by its shape? You could also display herbarium specimens of various trees, shrubs and herbs. Can you identify the specimens?
Extra Activity: Collect different fungi.
6.24 Trees, palms and ferns
Be able to identify some trees, palms and ferns.
You should know some examples of the trees, palms and ferns listed. Bring a branch of a tree, leaf of a palm and a whole fern into the classroom, e.g. Acacia (clearings), Albizia (fuelwood tree), Betel palm, Bracken Fern, Breadfruit, Campanosperma (swamp tree), Lemon and lime (citrus), Cocoa, Coconut, Coffee, Edible Fern, Takuma, Epiphytic Ferns (live on trees), Eugenia (forest tree), Fig, Filmy Fern, Guava, Ivory Nut Palm, Kamarere (Eucalyptus deglupta), Leucaena (shade tree), Mango, Mangrove (swamp tree), Ngali nut (Canarium), Nipa palm, Oil Palm, Pandanus palm, Papaya, Podetia (forest tree), Rubber, Securingia (fuelwood tree), Soursop, Teak, Terminalia (forest tree), Traveller's palm.

1. Show the children samples of trees, palms and ferns. What is the main difference? [The shapes of the leaves.]
2. Draw some leaves of each, e.g. cocoa leaf, palm leaf, fern leaf.
3. Which trees, palms and ferns can they name? What are the uses of these plants?
4. List all the trees, palms and ferns they know.
Extra Activity: Naming Game.
Take the children for a walk. What are the names of the trees, palms or ferns seen during the walk? Sentence completion: The three main kinds of large plants are: 1. [Trees, e.g. Breadfruit, Leucaena] 2. [Palms, e.g. Coconut] 3. [Ferns, e.g. Takuma].
Extra Activity: Collect the following stages of a known tree, e.g. mango or Terminalia, seed, young plant, plant with flowers and fruit. Show the children t
6.25 Protect our trees
See diagram 9.53.9: Conserving trees
Be able to state why you should carefully protect your bush trees.
Use Trees are part of out natural heritage. We should make sure that all the different kinds of trees in your forests will be there in the future for the next generations. Forest trees have survived for thousands of years so why should you worry about them now? The population is increasing rapidly so there are now more people who want to use the products of the forest. Trees can be cut down easily by modern equipment such as chain saws. Logging of a forest has the result that all the largest trees are cut out. They may grow again. Cutting down a forest for wood chipping means that all trees are cut down and the same type of forest may never grow there again. Burning off grass lands kills any small trees.
1. Explain the importance of the forest. It is not just the bush. It has been a source of benefit for the people for a long time. Divide the class into groups. Each group must list the benefits to the people of the forest. Read out their list. Summarize the benefits on the chalk board.
2. List the names of bush trees that benefit people, e.g. cotton tree for stuffing pillows, Kamarere for timber and fuelwood, local nutmeg for eating.
3. Why you should not burn grassland? [The small tree seedling cannot grow and so the forest shrinks.]
4. What can you do to tell other people to conserve your trees?
Extra Activity: Talk from a forestry officer. The teacher should have previously informed the officer ahead of time for this exercise.
6.26 Describe grasses
See diagram 9.52: Grasses
Be able to 1. describe and identify the parts of grass and how they grow and 2. distinguish between grasses and sedges.
Use Grasses are the most useful group of plants. They have many small flowers and, except bamboo, grow close to the ground as runners or tufts. They have a special shape of leaf. Each leaf has a leaf blade, sheath and a ligule. They have parallel veins. Sedges have angular stems while grasses have round stems.
1. Give each group different kinds of grass. What do you call these plants? [Grass.] How are they different? [Tufted grass grows upright in a clump, rumour grass grows along the ground, bamboo is very tall and has a woody stem, cereals have large grains that you can eat.]
2. Look at the tufted grass and runner grass. How are the grasses different from bushes and trees? [Grasses are small plants, they may cover the ground, they have very small flowers and seeds, cereals produce grains. They have fibrous roots.]
3. Describe the grass roots. [Lots of small roots that grow from the same place, bushes and trees have a long tap root and smaller roots from growing along it.]
4. Describe the grass stem. [Most grasses have no stem, cereals and bamboo have a kind of stem that may be hollow.]
5. Describe the grass leaves. [The leaves are quite different from the leaves of bushes and trees, grass leaves are long and thin, part of them wraps around the other leaves or stem and part hangs down when it is old.]
6. Can you see the grass flowers? They are very small. Large grass seeds are called grain.
7. Pull off a while grass leaf and draw it.
(8) Pull off a sedge stem and compare with a grass stem.
Extra Activity: Drawings of grass plants.
6.27 Describe palms
See diagram 9.50.2: Palms
Be able to describe different palms and how they grow.
Use examples or pictures of palm plants, mosses and ferns. Edible palms include coconut, sago, oil and date palms.
1. Give each group a piece of palm leaf. What kind of plant is it from? [Palm.] How is it different from the fern or moss leaf? [It is much bigger, hard and shiny, divided into strips.]
2. How many useful palms do you know? [Coconut, sago, raphia, nipa, betel, oil palm, pandanus.] Do you know a useful palm that grows in the desert? [date palm.] There are many other kinds of palms in the forest. Do you know any use for them?
3. Show the children a picture of a palm tree or show them a palm outside.
What do you notice about the following parts of a palm?
The stem [It grows straight up, no branches.]
How the leaves grow [The leaves grow from the top of the stem, the youngest at the tip, the oldest hang down.]
The size of the leaves [The leaves are very big.]
The shape of the leaves [Split into strips or fan-shaped.]
The roots [Shallow roots that may stick out before going into the ground.]
The fruit [They can be large and heavy.]
4. Palms are one of the most useful plants in the world. Palms are also special trees in the forest. They grow very slowly so you should not cut them down unless you have a good reason. Be kind to palms.
Extra Activity: Visit the forest and study the sago palm. Before it flowers, you cut it down and wash the sago starch out of its trunk. The leaves make good palm thatch.
6.28 Describe ferns and mosses
See diagram 9.48.1: Ferns | See diagram 9.47.2: Moss
Be able to collect and describe different ferns and mosses.
Use Different types of ferns and mosses:
1. tiny, filmy ferns 2. bracken ferns that grew up out of the ground 3. tree ferns that are tall and have a kind of trunk 4. epiphytic ferns that grow high up on other plants and grow high up on other plants to reach the light 5. magnifiers.
Ferns do not have flowers, seeds or fruits. They reproduce by tiny round spores from the underside of their leaves called fronds. If they press a frond down on to inked paper, you can get an outline of where the spores are made. Ferns usually live in damp places or in the forest. Mosses are tiny single plants that crowd together like the pile of a carpet. Ferns are found in damp places. They have root-like structures called rhizoids Use ferns to the lesson or prepare to go out to the forest to see different kinds of ferns. Collect ferns with brown spores underneath. The spores underneath are called sori, singular "sorus". They are used for reproduction.
1. Show the class the different kinds of ferns and mosses. Have you seen them before? Can ferns be poisonous? [Yes, some ferns can make cattle sick if they eat them.]
2. What do you see on the fern leaf (frond)? [Brown balls are under the frond.] They are called spores or sori and are like little seeds. They are used for reproduction.
3. Draw a fern leaf. How is it different from the leaf of a tree? [It is much thinner and has a different shape.]
4. Does it have flowers and fruits? [No.] Does it have a stem? [Some have a kind of stem.] Does it have a tap root? [No, it has little roots.]
5. Look at a piece of moss carpet. Can you see the separate moss plants standing up straight? Can you separate one moss plant? Why do they all stand closely together? [To keep water between them and not get dry.] Look at a single moss plant with the magnifier. Does it have flowers? [No.] Does it have leaves, stem and root? [Yes, but they are very small and simple.]
Extra Activity: Make spore outlines on inked paper, or draw a harvested sample from a moss plant. Use the magnifier for the initial observation.
6.29 Protect our coral reefs
See diagram 4.62: Conserving land
Be able to explain why you should stop loss of land and coral reefs by controlling water runoff.
Use Examples of ridges and terraces.
If land is perfectly flat it cannot be washed away by rain, but it may be cut away by a river. Heavy rain can cause loss of nutrients by leaching. Sloping land can be washed away if water washes over it. Loss of land can be prevented by covering the soil with grass and trees. When people make gardens on slopes some soil will be washed into the valley below to become valuable topsoil. However, that topsoil will be lost if it is washed into the river and becomes silt. The silt can cover the animals in the coral reef and kill them. Children should know how to prevent loss of land and coral reefs.
1. What will happen to the bare soil on slopes if it rains? [It is washed down.] Where does it go? [On to the land below.] Where can it go? [Into the river.] Where does the silt go? [Out to sea, it can cover the coral.]
2. How can you stop water washing the soil down? [1. Grow crops in horizontal strips 2. Build terraces to hold the soil back 3. Dig horizontal ridges 4. Dig drains to carry water away.]
3. What is the best way to protect a sloping level? [Cover with plants.]
Extra Activity: Visit to ridges and terraces.
6.30 Protect our soils
See diagram 4.62: Strip cropping
Be able to explain why you must change the traditional methods of gardening and burn less bush.
Use Traditional gardening environment, modern improvement methods showed and explained by agricultural officers.
This lesson is not designed to teach children that the traditional methods of gardening were wrong. They were excellent methods because they allowed soil fertility to be restored by the forest and efficiently used the garden land by having a variety of sized food plants growing in the gardens. They provided enough food for the people. The system should be changed now because of the growth of population. However, you should try to improve the traditional methods.
1. Describe their traditional method of shifting cultivation.
2. Explain that the hot wet climate of the Solomon Islands helps all plants to grow very quickly. The result is that in traditional gardening you cannot use the garden for more than a few years because the fast growing weeds take over.
3. Another reason that people shift a garden is that the crops take out nutrients from the soil, especially potash and phosphorus and so the soils become less fertile. 4. The traditional method was to let the forest grow back over the garden land and not use it again for 15 to 20 years. This is called the bush fallow system. During this time the rotting leaves from the forest would restore the soil fertility.
5. However, now the population is increasing rapidly and the people are moving to towns. There is not enough land to allow the long fallow periods so people are using the land again for gardens before soil fertility is restored. Forest is changing to grassland and soil is being washed away.
6. Agricultural officers believe that one way to conserve soil fertility would be less burning of cleared land. Burning of loose leaves and sticks returns some nutrient to the soil in the ash and it also kills some diseases and weed seeds. However, some plant nutrients are lost in the smoke. Much ash is washed away, the bare ground is eroded by heavy rain and plant nutrients can be washed away or leached.
7. The best method is to cut the trees low but not harm the stumps so that they can grow again easily. This is called secondary forest regeneration. Burn the wood and trash that get in the way but use the leaves for mulch.
Extra Activity: Visit a traditional garden to see how the cut bush is burned.
6.31 Describe soils
See diagram 4.36.3: Examining soils
Be able to link different types of soils with their physical properties.
Use A large container of garden soil, different kinds of soils, e.g. sand, clay, swamp, magnifiers, sheets of paper (the different soils should be placed on these), glass jars, buckets of water, table of results.
Examine soil types with special reference to the texture types.
1. Give soil samples and other materials to each group. Label each soil sample Put garden soil in the glass jar, until it is about one third full of soil. Pour water from the bucket into the jar containing the soil until the jar is two thirds full. Put the lid on the jar and shake strongly, watch what happens inside the jar for a few minutes. [Solid particles settle to the bottom.]
2. What do you see from top to bottom in the jar? [Floating plant matter, clay suspended in the water, fine sand, coarse sand, pebbles.] Put this jar where it will not be moved as they will be looking at it later in the lesson.
3. Take each sample of soil (including garden soil) and feel and look at each closely with the magnifier to see: the colour, the way the soil holds together, the size of the particles, how much water there is in the soil, how much plant matter there is in the soil, if any animals are present, the feel of the soil.
4. Complete their table of results.
Extra Activity: Use another soil sample from home for further testing.
Table of Results
Which soil has the darkest colour? [Swampy soil.] Which soil feels the most sticky? [Swampy soil.] Which soil feels the driest? [Sandy soil.] Which soil is held together most loosely? [Sandy soil.] Which soil has the most plant matter? [Garden soil or swamp soil.]
6.32 Test soil texture
Be able to show a simple method of determining the texture of soil.
Use Samples of different soils, e.g. clay, silt, sand and a small quantity of water.
The texture of a soil affects soil characteristics such as ease of cultivation, its ability to accept water and how much water it can hold for plants and other organisms to use. A quick and simple technique to measure soil texture is useful when deciding agricultural activities such as ploughing.
Soil Texture Reference Information
Sands, grains do not stick together, cannot be moulded, single grains stick to fingers.
Loamy sands, form fragile shapes that just bear handling, give short ribbons that break easily, discolour fingers.
Fine sandy loams form shapes that will just stand handling, fine sand can be felt in some, otherwise it feels smooth, may feel greasy if much organic matter is present, will form ribbons 15 to 25 mm long.
Silty loams, will stick together but will crumble, very smooth and silky, will form ribbons 25 mm long.
Clay loams, sticks together to form shapes, with a rather spongy feel, plastic when squeezed between thumb and forefinger, smooth to manipulate, will form ribbons 40-80 mm long.
Clays, smooth, plastics casts, some resistance to manipulation (toughness), form ribbons at least 80 mm long, depending on heaviness of the clay.
Sand grains can be felt in sandy clays that form ribbons 40-50 mm long.
1. Take a small amount of soil enough to fit in the palm of the hand. Discard obvious pieces of gravel.
2. Moisten the soil with water, a little at a time and knead until there is no apparent change in the feel of the ball. The moisture constant should be such that the ball just fails to stick to the fingers.
3. Inspect the sample to see if sand is visible, if not, it may still be felt and kneaded as the sample is worked.
5. Finally, squeeze it out between the thumb and forefinger with a sliding motion and note the length of self-supporting ribbon that can be formed.
6. Give the children some pure sand, silt and clay to test. Then test soil from 1. a garden 2. a forest 3. bank of a river 4. top of a slope.
Extra Activity: Texture museum. Try to collect samples of soil with the six types of texture. Keep them in glass jars for reference.
6.33 Fertilizing soil
See diagram 6.65.1: | See diagram 6.65.2: | See also 6.9.14: Composting
Be able to state the four reasons for fertilizing soil.
Use A drawing of the soil nutrient cycle, evidences of fertilizer activities and soils in the surroundings.
To fertilize means to make the soil richer by adding plant nutrients that will make the crops grow better and produce a greater yield when they are harvested. There are four reasons why the soil must be fertilized: 1. Some soils have been formed from rocks that did not have enough of the chemicals that make plant nutrients. In some tropical countries the parent rock has little potash in it and so the soil formed from that rock will be deficient in potassium. 2. Soils may lose plant nutrients when rainwater washes through them. This is called leaching. Soils that have an open texture and do not have enough clay and rotten plant material in them lose many plant nutrients by leaching. 3. When a crop is harvested and taken away, some plant nutrients are taken away as well. These plant nutrients must be replaced if the soil is to remain fertile and produce good crops. Some plants need more of some particular plant nutrients than others. You take away many those nutrients when the plants are harvested. 4. Fertilizing increases the yield of a crop and allows us to feed more people or make more profit if the crop is sold. The work done in making compost and adding it to the soil is rewarded by an increase in profit. The plants get only a small fraction of their total plant nutrients from the soil. Most of the nutrients come from the air. However, crops will not grow well unless they have all the plant nutrients they need. [In this lesson you can teach the four reasons by using the diagram shown in the diagram. Draw the diagram on the chalk board. Start with the soil, then the sweet potato, then the pig, then show the loss of nutrients to the market and by leaching.
1. Today you will learn the four reasons why you must fertilize the soil. We will learn from a diagram. First, here is the soil. The soil contains plant nutrients such as nitrogen, phosphorus and potash. We can see rocks deep in the soil. Are all the rocks the same? [No.] Do all rocks give the same nutrients? [No.] In some places the rocks are usually old coral reefs or volcanic rocks. These rocks do not contain much potash, so the soil needs more potash.
2. What happens to the soil nutrients? [They go into the sweet potato plant.] What else goes into the plant, it is shown in circles. [Sunlight, carbon dioxide, water.]
3. How do the nutrients get out of the plant? There are two ways. [The pig eats the plant or the plant dies.] Where are the nutrients now? [In the pig or in the rotten leaves on the ground.]
4. How do the nutrients get back to the soil? [Rotten leaves go into the soil or via the pig's faeces or urine.] Do all the plant nutrients get back to the soil? [No.] Where do they go? [Pigs and tubers go to the market and some nutrients are lost by leaching.
5. How do you grow more sweet potato and pigs? [By using fertilizer.]
Extra Activity: Make a chart of the nutrient cycle.
6.34 Chemical fertilizers
Be able to explain how chemical fertilizers should be used.
Use Illustrations and real examples of chemical fertilizers, technical information, artificial fertilizers.
It is unlikely that children will be using chemical fertilizers but you can explain. 1. Chemical fertilizers can increase yields so much that all village gardeners should think about using them. 2. Chemical fertilizers are expensive because they are all imported. 3. The use of chemical fertilizers must be exactly as recommended by the agricultural officers. Otherwise, money will be wasted. Recommendations are based on type of crop and soil grouping.
Soil Grouping: 1. Coral beach sand soils are weakly weathered, alkaline, have moderate amounts of phosphorus and low amount of potassium. 2. Mineral beach sand soils are weakly weathered, weakly acid, and have moderate amounts of phosphorus and potassium. 3. Alluvial soils are near rivers or on lower slopes, weakly weathered, weakly acid or alkaline, with good amounts of phosphorus and moderate amounts of potassium. 4. Yellowish, brownish, reddish clay soils are mainly on coral limestone are weathered, acid, with good amounts of phosphorus but low amounts of potassium. 5. Reddish clays on volcanic rocks are strongly weathered, acid, low on phosphorus and potassium. From these descriptions of the soil groupings you can see that most gardens may not have enough potassium in the soil. You will need a fertilizer bag. Find out the cost of fertilizer in the local area.
1. Have you seen chemical fertilizer being used? Show the children a fertilizer bag or packet. Read the label for them. What is the price of this fertilizer?
2. Explain why these fertilizers are needed but why you should use them carefully based on the advice of an agricultural officer.
Extra Activity: See technical information over. Visit a plantation or project to see the use of chemical fertilizer.
6.35 Burn candle over water
See diagram: 20.1.5
Be able to observe what happens when a candle burns.
Use Glass jars, candles, tray, water, a ruler.
Practice this demonstration before the lesson.
Method 1:
1. Fix a candle to floating cork. Put some water in the tray so that the water level is about half the length of the candle.
2. Measure the depth of the water in the bucket. Measure the length of the jar. The jar is full of air so you are really measuring how much air in the jar. Light the candle.
3. Place the jar over the candle quickly so that the mouth of the jar is under water.
4. What do you see? [1. The candle flame gets smaller, splutters then goes out. 2. While the candle was alight, some air bubbles came out from under the jar. 3. when the flame went out water rose in the jar and the water level dropped slightly in the bucket. 4. Some water condensed inside the jar and on the wick.]
5. Why did the candle flame go out? [The oxygen in the jar was all used up. It was converted to carbon dioxide gas. The blackened wick is carbon ]
6. Why did some air bubbles come out from under the jar? [The candle flame heated the air in the jar causing the air to expand.]
7. Why did the water move up the jar? [When the candle flame went out the gases in the jar cooled and contracted to a smaller volume than before. The air pressure on the surface of the water in the bucket pushed the water up into the jar.]
2 Repeat the experiment with one, two and three happy birthday cake candles
1. Fix the candles to Plasticine at the bottom of the tray then do the experiment as before
2. The air in the jar is less heated with smaller candles so you probably do not see bubbles coming out from under the jar. The jars contained about the same amount of oxygen but the jar with the three candles showed the greatest water rise because more heat was produced by the candles in it.
Extra Activity: Why does a candle burn? [When you light a candle wick, some heat from the burning wick melts the wax at the top of the candle. The melted wax rises in the wick because of capillary forces and some of that wax evaporates to form a vapour that rises then burns with a bright flame.]
6.36 Candle "lava"
Cooling candle wax looks like cooling lava 1
Be able to observe the shapes formed by falling drops of molten wax and discuss how molten rock cools.
Use Candles, matches and a safe place to drop the wax.
Find time to do the activities recommended here.
1. Hold a lighted candle about 30 cm above the tray so that a drop of melted wax falls on the tray. BE CAREFUL!
2. Repeat this procedure several times, holding the candle at different heights. Observe the cooled drops.
3. From which height did the molten wax spatter the most? The least? What shape did the cooled wax take?
4. Explain that volcanoes sometimes shoot out molten rock called lava. Does this experiment explain the cooled shapes of lava from a volcanic eruption?
Extra Activity: Study a volcano cone. Does the candle wax experiment help you understand how the cone was formed?
6.36.1 Cooling candle wax like cooling lava 2 - speed of cooling and crystal size
See diagram: 23.7.1 Speed of cooling
Be able to discover whether the speed of cooling affects the size of crystals and then to discuss why rocks have different sizes of crystals.
Use Small glass tubes, or any other glass container you can heat, burner, or a candle in a holder, a wooden peg, two glass jars, naphthalene (moth balls) or crystals of copper (II) sulfate or salt or sugar, silver foil or paper or cloth.
An igneous rock consists of crystals produced when the rock cooled from a very hot liquid state. Rocks that formed deep in the ground such as granite have large crystals. Rock that formed on the ground after the liquid rock came out of volcanoes, such as basalt, have small crystals. Rocks formed deep in the ground cool slowly. Rocks formed above the ground cool quickly.
1. In this lesson you will imitate the cooling of an igneous rock.
2. Fill the two test-tubes with naphthalene to the one quarter mark, Using the wooden peg, gently heat the test-tubes until the naphthalene starts to melt.
3. Move the test-tubes about to distribute heat evenly. Then remove the tubes from the flame and shake gently. Heat a little more, then shake again. Keep doing this until all the naphthalene has melted, or dissolve as many crystals as you can in a small amount of warm water.
4. Quickly wrap the test-tube containing the melted naphthalene or crystal in silver foil to keep it warm. Then stand it in a large beaker.
5. Rapidly cool the second lot of melted naphthalene or dissolved crystals in a beaker of cold water.
6. Observe the naphthalene or dissolved crystals in the two tubes and note carefully the size of the crystals formed. Why the crystals in the tubes are different sizes. [Larger crystals formed in the tube wrapped in foil because it cooled more slowly than the tube in the cold water.]
7. What is the relationship between the rate of cooling and crystal size of igneous rocks? [The slower the speed of cooling the larger the crystals formed.]
Extra Activity: Can you find rocks that cooled quickly?
6.37 Electric circuit
See diagram: 32.2.1
Be able to set up an electric circuit to light a light bulb.
Use Torch light batteries, wires, sticky tape, bulbs, bulb holders.
Electricity can only be generated if there is a complete circuit. Revise electric circuits before the lesson.
1. Give each group a battery, wires and a light bulb. You must need some sticky tape to hold the wires on the bulb contacts. Do not show the children what to do. Light the bulb. Which group can do it first? Can you tell the other groups how you did it? This is one way of encouraging the scientific attitude.
2. Look at the torch battery. What do you see at each end? [The top has a bump marked on it and is marked "+", the bottom is marked "-". Each end is made of metal.] How did you make the bulb light? [One wire touches one end of the battery. The other wire touches the other end of the battery.]
3. Look at the light bulb. What do you see inside the glass bulb? [A thin twisted wire called the filament.] Is there a metal part? [Yes, below the glass part.] How did they make the bulb light up? [One wire touches the bottom of the metal part, the other wire touches the side of the metal part.]
4. Electricity travels along a path. If the path is blocked, then electricity cannot keep flowing. The whole path along which the electricity travels is called a circuit. A broken path is called an open circuit.
Extra Activity:
1. Break open an old torch battery with the back of an axe. Be careful!
Can you see the 1. cardboard cover 2. zinc case 3. black chemical which is a sticky powder 4. a black carbon rod down the centre of the battery?
6.38 Electricity conductors
See diagram: 32.2.1
Be able to use a test circuit to show which substances are conductors of electricity.
Use Batteries, bulb holders (not essential), pieces of wire (30 pieces if bulb holders are used), connecting boards, many items for testing, e.g. nails, string, wood, plastic rulers, chalk, rubber, leaves etc.
1. Use the chalk board diagram to show the children how to set up their testing circuits. Give out the materials and tell them to set up their own circuits.
2. Trace the path of the electricity from one end of the battery to the other through the circuit. Is the pathway complete? [No.] Does the bulb light? [No.] Put a piece of wire across the break between the two drawing pins. What happens? [The bulb lights.] Why? [The wire completes the pathway and allows the electricity to flow through the circuit.]
3. Test each item to see if they will allow electricity to flow by placing them to touch two drawing pins. How will you know if electricity is flowing? [The light bulb glows.]
4. Divide the items into two groups. Group 1 contains things that electricity will flow through, conductors. Group 2 contains things that electricity will not flow through, insulators. When all the groups have finished, fill in the table of results on the chalk board.
5. Most metals are good conductors of electricity, e.g. iron, tin, and copper are used to make wires. Most non-metals do not conduct electricity, e.g. glass, plastic, clay, rubber, wood, air. They are called insulators and are used to stop the flow of electricity. Can you see insulators on an electricity pole? [Yes.]
Extra Activity: List conductors and insulators you can see in a home/ town. Show the children the large white insulators on electric power poles. Never touch power lines with sticks or the string of a kite. Sometimes power poles will conduct electricity will conduct electricity if they are wet so the children should not touch them. If you see power lines lying on the ground, you should tell people to keep away and inform local government.
6.39 Electric torch (flashlight )
See diagram: 33.4.1:
Be able to trace the circuit in an electric torch.
Use A torch with metal sides and a torch battery opened with the back of an axe.
Take a torch to pieces and put it together again.
Show the class the torch, turn it on and off with the sliding switch. Dismantle the torch. Show the class the different parts: switch, metal case. Use the arrows to show them how these parts are part of a circuit. Show the children the opened battery. The electricity comes from the zinc case when some zinc dissolves in the black chemical. In the very old batteries so much zinc dissolves that holes in the zinc case let some chemical leak out. The carbon rod does not dissolve. Why should the two batteries be in the same direction in the circuit? [Otherwise they would push electric currents against each other.] Take out the batteries in a radio. Are they all in the same direction in the circuit? [Yes.] The electrical strength of a battery is measured in volts. How many volts in one battery? [1. 5 volts.] If the batteries are put end to end in the circuit, how many batteries do you need for a total of six volts? [Four.]
6.40 Hanging magnets
See diagram: 29.1.6
Be able to predict what will happen when hanging magnets are brought near each other.
You will need: Bar magnets, two for each group, thin string, pocket compass. This lesson teaches the rule about magnetic poles: "Like poles repel, unlike poles attract".
1. Tie the string around each magnet and hang them away from each other. Look at the pocket compass. Are both hanging magnets pointing in the same direction? [Yes.] Which way are you pointing? [North-South.]
2. Mark the North Pole on each magnet with a piece of chalk. It may already be marked with red paint or a small hole. Tie the end of the string of one magnet to the edge of the desk so that it hangs in a fixed position. Move the North Pole of the other magnet towards the North Pole of the fixed magnet. What happens? [The North Pole moves away.] Move the South pole towards the North Pole of the fixed magnet. What happens? [They move together.]
3. Pull together = attract, push apart = repel. Draw the following diagram on the chalk board and tell them whether the poles attract or repel.
Extra Activity: Repeat the last step but have paper or glass between the magnets. Do you still attract or repel each other? [Yes.] What does this show you about properties of magnets?
6.41 Make electromagnets
See diagram 32.2.1:
Be able to make an electromagnet.
Use Pieces of insulated wire, nails about 7 cm long, batteries, pins or paper-clips that can be picked up by a bar magnet.
Winding the wire on the nail. The wire must be wound around the nail in one direction only. It must not be crossed over and there should be about thirty turns around the nail.
1. Give each group one piece of insulated wire, one long nail, pins and paper-clips. Put the nail near some pins and see if it is a magnet. Is it a magnet? [No.]
2. Show the class how to wind a piece of wire around a nail. Test the nail with the wire on it and see if it is a magnet. Is it a magnet? [No.]
3. Use scissors to cut away one cm of the plastic at each end of the wire so that the ends are bare. Connect the ends of the wire to the battery and see if the nail with the wire around it is a magnet now. Is it a magnet? [Yes.] Pick up some pins with the electromagnet. Now disconnect the wire from the battery. Is it still a magnet? [No.]
4. The electromagnet is an important part of a petrol engine. When electric current flows, the magnet is on, when no current flows, the magnet is off.
Extra Activity:
What happens to the "strength" of your magnet when you use:
1. less turns of wire around the nail? [The magnetic strength is less.]
2. two batteries instead of one? [The magnetic strength is greater.]