School Science Lessons
2023-03-13
Primary Science Lessons, Year 6
Contents
Suggested answers to the teacher's questions are shown within [square brackets].
6.18 Atmospheric pressure
6.34 Chemical fertilizers
6.03 Chicken life cycle
6.11 Coins on a slope
6.33 Cooling candle wax
6.31 Describe soils
6.37 Electric circuit
6.38 Electricity conductors
6.41 Electromagnets
6.21 Estimating
6.28 Ferns and mosses
6.12 Float Plasticine boat
6.13 Forces of friction
6.01 Forest food chains
6.26 Grasses
6.40 Hanging magnets
6.08 Heated liquids expand
6.15 How far can you see?
6.19 Moon and tides
6.36 Mulch saves water
6.27 Palms
6.22 Pendulum tells the time
6.23 Plants take in water
6.39 Plasticine boat sinking and floating
6.29 Protect coral reefs
6.02 Protect turtles
6.10 Pull with pulleys
6.42 Rain on soils
6.17 Relative humidity
6.45 Reproduction, birth and care for baby
6.43 Reproduction, male
6.44 Reproduction, female
6.25 Soil fertilizers
6.32 Soil texture
6.20 Southern Cross
6.24 Trees, palms and ferns
6.01 Forest food chains
See diagram 9.311: Food chain animals
In this lesson introduce the idea of food chains in the forest and start them 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 flow.
Teach the children to study animals in the forest and discover food chains.
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.
1.0 Animals without backbones (Invertebrates)
1.1 Microscopic single celled animals (Protozoa)
1.2 Flat worms, parasites in animals (Platyhelminthes)
1.3 Round worms, parasites in animals (Nematode)
1.4 Ringed worms, earthworms (Annelid)
1.5 Jointed legged animals (insects, spiders, ticks, centipedes, millipedes (Arthropod)
1.6 Slugs and snails (Mollusc)
1.7 Animals with backbones (Vertebrates)
1.7.1 Frog, toad (Amphibians)
1.7.2 Lizard, tortoise, crocodile (Reptiles)
1.7.3 Parrot (Birds)
1.7.4 Flying fox, dog, cat (Mammals)
2.0 Plants in the forest and grassland
2.1 Green colour in water and wet soil, single celled plants (Algae)
2.2 Moss (Bryophyte)
2.3 Ferns, filmy ferns, bracken, tree ferns, epiphytes (Pteridophyte)
2.4 Pine trees, cycads and palms (Gymnosperms)
2.5 Grasses and shrubs, trees, vines (Flowering plants, Angiosperms)
3.0 Mould, bracket fungi, mushrooms (Fungi)
4.0 Aerobic bacteria, need air, anaerobic bacteria, live in mud, both cause rotting.
6.02 Protect turtles
See diagram 9.307: Turtle
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, which are part of their 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 we 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.
We 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.
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 we should NOT kill them
We must respect all animals.
Animals should not become extinct.
Animals are part of our natural heritage.
Turtles are beautiful creatures that should be admired.
3. Explain why they are in danger of animals becoming extinct:
The custom of killing for special occasions or to honour special people.
However, some customs are no longer respected.
People now have motor boats.
Foreign fishing boats drown the turtles when they are caught in nets.
4. Explain how they can protect turtles:
Protect eggs and hatched baby turtles,
Protect laying mothers,
Protect turtles at sea.
5. Turtle sightings.
Encourage the children to report whenever they see these animals.
Give a small reward for each sighting.
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.
Teach the children to explain why we should protect turtles and crocodiles.
Tell the teacher where you saw the turtle and what kind it is, then the teacher will give you a prize!
6.03 Chicken life cycle (Primary)
See diagram 50.6.2: Chicken life cycle
See diagram: 50.6.0: Parts of a chicken
Objective: To explain how the mother hen can make baby chickens.
Discuss the diagram for this lesson with the head teacher before teaching 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.
6.08 Heated liquids expand
See diagram 20.1.2: Heat conical flask
See diagram 20.1.3: Heat with hands
Teach the children 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 them 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 as 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 as 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.]
7. Show the children a thermometer and show how the temperature changes when the bulb is placed in hot water, then in cold water.
Explain how thermometers are used to measure the air temperature and your body temperature.
6.10 Pull with pulleys
See diagram 21.5.0: Types of pulleys
Use pieces of string three metres long, small pieces of string 40 cm long, pulleys (fixed and movable), bags full of sand or soil
(for loads), sticks or strong rulers.
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 not 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.
Teach the children to use pulleys to change the direction of a pull and to move heavy loads.
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:
1. a fixed pulley changes the direction of the force and
2. 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.
Draw a diagram on the chalkboard 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 chalkboard 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 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.]
6. 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.]
6.11 Coins on a slope
See diagram 16.160: Start and stop
See diagram 16.4.0: Forces
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 weight of objects.
Teach the children to explain why an object can slide down a slope and move another object.
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.]
5. 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.]
6. 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 weight of the coin.]
The weight of the object is the pull down caused by the force of gravity.
7. 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.
8. 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.
9. 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.]
10. Can you explain why a ripe mango or orange fruit drops to the ground from the tree? 11. 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. See a 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 Float Plasticine boat
(1 millilitre, mL, is a basic unit of capacity) Use Plasticine, a jar and water.
An object that sinks can be made to float by increasing its volume so that the weight of the object is less than the weight 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.
Teach the children to explain why an object that sinks in water can be made to float.
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 weight 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 weight 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.
8. How does step 7 above explain floating of ships? [The weight of the ship is less than the weight of the water displaced.]
6.13 Forces of friction
See diagram 17.264: Reduce friction with ball bearings
Teach the children to explain what causes friction and how you can reduce it.
Use three new match boxes, full of sand and full of nails, heavy book, piece of string, lead pencils.
Friction has both advantages and disadvantages.
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, e.g. 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.
See diagram 3.1.2.6: Matchbox
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
See diagram 3.1.2.6: Matchbox
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 chalkboard.
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.]
5. 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, because 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.
6. How does friction help in increasing or decreasing the speeds of athletes at sports meets?
[Runners need friction between their shoes and the track to give forward motion.
Soccer players use friction between the air and the soccer ball to bend it in flight.
They kick the ball to give it spin to increase friction with the air to make the ball curve.]
6.15 How far can you see?
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 arm's 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.]
6.17 Relative humidity
See diagram 37.114: Wet and dry bulb thermometer
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 per cent
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.
Use a bottle and running water.
You can make a wet bulb thermometer with a thermometer and a piece of cloth.
Teach the children to explain the importance of humidity in your climate.
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.
5. 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 Atmospheric pressure
| See diagram 12.272: Spurting tennis ball
| See diagram 12.307: Mercury barometer
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. 1 010.7 mb 3 p.m. 1008.8 mb
December 9 a.m. 1 007.9 mb 3 p.m. 1006.2 mb
Teach the children to state how atmospheric pressure (air pressure) affects weather.
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.
6. Read a barometer every day.
Note when the pressure is high and when it is low.
7. Make a table to show some daily records of air pressure at 9.00 a.m.
6.19 Moon and tides
See diagram 36.28.1: Phases of the moon in a classroom
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 Halley'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.
Teach the children to explain how to make and use different kinds of natural fertilizers.
Try to find out the times for high and low tide and the phase of the moon.
Teach the children to observe the moon and tides and try to find a connection between their movements.
1. When do you get high tides and low tides during the day? [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 moons? [30.]
How many days in a month? [31, 30, 28.]
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?
7. Make a 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.
8. 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 Southern Cross
See diagram 36.73: Southern Cross constellation
Teach the children 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 × 3, then dropping to the earth.
5. 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 Estimate lengths using your body
Teach the children to estimate lengths, using their body.
See diagram 6.21.1: Handspans
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?
6.21.2 Estimate total number using areas
See diagram 6.21.2: Estimate using areas
Teach the children to 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
See diagram 6.21.3: Estimate using divided samples
Teach the children to estimate total number, using areas.
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
See diagram 6.21.4: Estimate using layers
Teach the children to estimate total number, using layers.
Find the number of pages in a book.
Place the book on the table.
Place a ruler vertically to the table and the book
Count the number of pages for a small division, d1 of the ruler
Measure the vertical distance for all the pages of the book
Calculate the total number of pages
6.21.5 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?
6.21.6 Estimate heights
See diagram 6.21.6: Estimate heights
Teach the children to estimate the height of a flag pole or a tree.
Use 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
See diagram 6.21.7: Estimate area of a leaf
Teach the children to 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
See diagram 6.21.8: Estimate area of a mouse
Teach the children to 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.
Use lots of newspaper, pins, scissors and a ruler.
6.21.9 Estimate weight
Teach the children to 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 drink 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
6.21.10 Teach the children to estimate total number, using volume.
See diagram 3.1.2.6: Matchbox
Use 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 × N2).
5. Record this estimate in the table.
6.22 Pendulum tells the time
See diagram 15.1.1: Pendulum calculation
Teach the children 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.
1. 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.
2. 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
3. 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.]
Another way to measure time is to use clean sand in a double V-shaped container, e.g. an egg timer.
Commercial
Timer, three minute, sand hourglass /egg timer
6.23 Plants take in water
See diagram 6.23: Plants take in water
Teach the children to show that plants take in water.
Use small plants, e.g. Amaranths, glass jars, ink, cooking oil, water.
In this lesson we can show that plants take up water.
Groups of four children.
1. Give out plants and inky water.
Can the plants take in water
How can we show this? [We will put plants in inky water and clear water.]
Remove the plants after a few hours.
2. How will we see how much water plants take in? [We will put some oil on water, than it cannot evaporate.]
How will know that the water went into the plant and nowhere else? [The inky water will show us where the plant went.
We can also set up a control, which contains no plant.]
Set up the demonstration and put it aside.
3. Give out small plants with well-washed roots, and magnifying glasses.
Can you see the tiny root hairs?
Take the plant out of the inky water and break open the stem.
Can you see the ink inside?
What can we learn from this? [Roots take in water.]
Look at the water with the oil in top.
Is the level of water the same? [No, it has gone down.]
Why did it go down? [Some water went into the plant.]
Look at the control.
Did the water level go down? [No]
Why not? [There was no plant to take in the water.]
6.24 Trees, palms and ferns
See diagram 9.53.9: Acacia
Teach the children 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.
6. 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?
Teach the children to identify some trees, palms and ferns.
| See diagram 9.48.2: Bracken Fern
| See diagram 9.50.3: Pandanus palm
| See diagram 53.2: Coconut palms
| See diagram 9.50: Pine tree cone, (Conifer)
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.
5. Naming Game.
Take the children for a walk.
What are the names of the trees, palms or ferns seen during the walk?
5. The three main kinds of large plants are:
1. Trees, e.g. Breadfruit, Leucaena,
2. Palms, e.g. Coconut,
3. Ferns, e.g. Takuma.
6. Collect the following stages of a known tree, e.g. mango, young plant, flowers, fruit, seed.
6.25 Soil fertilizers
Natural fertilizers
| See diagram 6.65.1: Soil nutrient cycle 1
| See diagram 6.65.2: Soil nutrient cycle 2
Use soil, plant ash, manure, food wastes and cut grass.
In traditional agriculture, people cut down and burn the forest, plant crops, farm the land for a few years, then regeneration of a
secondary forest for 5-12 years before using the land again for crops.
This method of bush fallow is using natural fertilizers to improve the soil.
You can speed up this method and grow crops more often by using the following methods of natural fertilizing.
White plant ash is mainly potash.
Teach the children to explain how to make and use different kinds of natural fertilizers.
1. Explain the traditional methods of natural fertilizing.
How long is the fallow period in your area? Explain that by using the following methods the use of natural fertilizers is improved and
you can grow crops more often on the same piece of land.
2. The methods are as follows: 2.1 composting and mulching, 2.2 plant ash, 2.3 green manure, 2.4 liquid manure.
3. Composting means to make a compost heap on the ground out of layers of different wastes that can rot.
Such wastes include onion, plantain and yam peels from the kitchen or any soft wastes for that matter.
After how many days does their own heap start to lower in the soil?
4. If mulch covers the soil for a long time, the bottom layer becomes rotten compost.
Do not dig mulch into the soil unless it is rotten.
5. White plant ash (potash) contains plant food.
Burn old leaves and stumps until all the black charcoal is gone leaving only the white ash.
Spread it evenly over the soil.
Rake or dig it into the soil, do not let it blow away or wash away.
Compare this with what happens in farm lands or when farm land is cleared for local housing.
6. Green manure is made from local leguminous plants that grow and can be easily dug into the soil, e.g. cow pea and Crotalaria.
Digging in is hard work.
When these plants rot in the soil they fertilize it.
7. Liquid manure is used for small individual plants that may be burnt if you use new chicken manure or pig manure.
Fill a steel drum with water and throw in any animal manure.
Keep a lid on the drum, because it will smell.
If you pour some manure liquid on the soil, the plants will grow fast.
8. Take the children on a garden walk to see the four methods of using natural fertilizers.
Chemical Fertilizers
Teach the children to explain why chemical fertilizers are used and how you are put in the soil.
Use samples of chemical fertilizers.
Chemical fertilizers are made in factories overseas.
For example, superphosphate is made from phosphate rock.
these fertilizers are expensive to buy and can easily be wasted if not used properly.
There is no need to use them in school gardens, but children should know about them.
Some plant foods such as potash are not enough in tropical gardens to get good root crops.
A small amount of white plant ash or chemical fertilizer increases the yield greatly.
Plantation crops such as coconut and cocoa may need a lot of chemical fertilizer because the crops have high yields, year after year.
Chemical fertilizers replace the plant foods lost from the soil.
The three main plant foods in mixed chemical fertilizers are nitrogen (N), phosphorus (P) and potash (K.]
Other plant foods such as boron (B) may be used for vegetables.
On the chemical fertilizer bag you can read (a) the name of the factory, (b) the weight of the fertilizer, (c) the grade formula,
e.g. NPK 12: 4: 19, showing the amount of main plant foods.
Another mixed fertilizer NPK 12: 12: 17 contains more phosphorus and less potash.
Also there are some simple fertilizers which contain mainly nitrogen, sulfate of ammonia, urea, phosphorus superphosphate, potash,
muriate of potash, sulfate of potash.
Chemical fertilizers are put in the soil in three ways:
1. Spread over the soil before planting then plough in,
2. Place the fertilizer in a band under the soil parallel to the seeds, called banding,
3. After the crops have started growing, give side dressing or top dressing of fertilizer between the rows.
Because chemical fertilizer is so expensive you should ask an agricultural officer to:
1. Tell you if fertilizers are is really necessary to increase yield,
2. Calculate the amount needed.
1. Show the children the fertilizer bag.
Tell the children that the bag contains chemical fertilizer that is made in factories in other countries.
If used properly you can increase the amount of food you can grow, but you are very expensive.
Read what is written on the bag aloud to the children and explain it to them.
2. Explain that there are different kinds of plant foods.
Some chemical fertilizers contain a mixture of food plants and others contain only one or two food plants.
For example sweet potato and coconut both need a lot of the plant food called potash.
For our vegetable garden we get enough potash from the white ash formed when trees are burnt.
However, on a coconut plantation a lot of the potash plant food is used in the coconuts so the chemical fertilizer called muriate of
potash, KCl, may be used.
3. Explain the three methods of putting chemical fertilizer in the soil, spreading, bonding, side or top dressing.
Explain why an agricultural officer should be asked to advise before using chemical fertilizers: 1.
need to calculate rate of application, 2. need to save money, 3. need to make sure that the fertilizer will increase yield.
4. Take the children to a garden or plantation where chemical fertilizer is being applied
6.26 Grasses
See diagram 9.52: Grass plant
Teach the children to:
1. describe and identify the parts of grass and how they grow and
2. distinguish between grasses and sedges.
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.
9. Drawing the grass plants.
6.27 Palms
See diagram 53.2: Coconut palms
See diagram 9.50.3: Pandanus palm
See diagram 9.50.2: Palm
Teach the children 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? [The 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 we should not cut them down unless you have a good reason.
Be kind to palms.
5. 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 Ferns and mosses
| See diagram 9.48.2: Pteridium bracken fern
Teach the children 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
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.]
6. Make spore outlines on inked paper, or draw a harvested sample from a moss plant.
Use a magnifier for the initial observation.
6.29 Protect coral reefs
See diagram 4.62: Conserving land
Teach the children to explain why we 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?
[2.1. Grow crops in horizontal strips,
2.2. Build terraces to hold the soil back,
2.3. Dig horizontal ridges,
2.4. Dig drains to carry water away.]
3. What is the best way to protect a sloping level? [Cover with plants.]
4. Visit to ridges and terraces.
6.31 Describe soils
See diagram 6.36.3: Examining soils
Teach the children to link different types of soils with their physical properties.
Use different kinds of soils in plastic bags, e.g. garden soil, sandy soil, clay soil, forest soil, magnifiers, water.
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 it strongly.
What happens inside the jar? [Solid particles settle to the bottom.]
2. What do you see from top to bottom in the jar? [Floating plant matter, clay suspended in water, fine sand, coarse sand, pebbles.]
Put this jar where it will not be moved, because they will be looking at it later in the lesson.
3. Examine each sample of soil
Which soil has the darkest colour? [Forest soil.]
Which soil feels the most sticky? [Forest soil.]
Which soil feels the driest? [Sandy soil.]
Which soil holds together most loosely? [Sandy soil.]
Which soil has the most plant matter? [Forest soils.]
6.32 Soil texture
Soil texture is the feel of the soil caused by the size of the soil particles.
2.1.1 Sandy soil has a coarse texture.
The sand particles are too large.
Sandy soils drain too quickly.
Sandy soils feel rough.
2.1.2 Clay soil has a fine texture.
The clay particles are too small.
Clay soils may not drain at all and the soil becomes waterlogged.
Clay soils feel smooth.
A good soil has a mixture of sand, clay and other particles between these sizes.
You can improve soil texture by mixing soils with different sized particles, i.e.
add sandy soils to clay soils add clay soils to sandy soils.
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:
1. Sands have grains that do not stick together.
Sands cannot be moulded.
Single sand grains stick to the fingers.
2. Loam sands form fragile shapes that just stand handling, give short ribbons that break easily, usually discolour the fingers.
3. Fine sandy loam forms shapes that will just stand handling.
Fine sand grains may be felt, but otherwise they feel smooth and may feel greasy if much organic matter is present.
Fine sandy loam may be formed into ribbons 15 to 25 mm long.
4. Silt loam will stick together, but will crumble.
Silt loam feels very smooth and silky and may be formed into ribbons 25 mm long.
5. Clay loam will stick together to form shapes.
Clay loam has a spongy feel and is plastic when squeezed between the thumb and forefinger.
It is smooth to manipulate and may be formed into ribbons 40-80 mm long.
6, Clays form smooth, plastics casts and show some resistance to manipulation, i.e.
toughness.
They may be formed into ribbons at least 80 mm long, depending on heaviness of the clay.
Sand grains can be felt in sandy clays that may be formed into ribbons 40-50 mm long.
Teach the children simple method to assess g the texture of soil.
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:
6.1. a garden,
6.2. a forest,
6.3. bank of a river,
6.4. top of a slope,
6.5. bottom of a slope.
7. Make a soil texture museum.
Try to collect samples of soil with the six types of texture.
Keep samples in glass jars for reference.
6.33 Cooling candle wax
See diagram 3.2.0.3: Speed of cooling
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 (mothballs) 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.
Teach the children to discover whether the speed of cooling affects the size of crystals and then discuss why rocks have different
sizes of crystals.
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.]
8. Can you find rocks that cooled quickly?
Candle "lava"
Cooling candle wax looks like cooling lava, describe shapes
Teach the children 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 30 cm above the tray to let drops of melted wax fall on it.
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?
5. Study a volcano cone.
Does the candle wax experiment help you understand how the cone was formed?
6.34 Chemical fertilizers
Teach children to explain how chemical fertilizers should be used.
1. 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 as follows.
Chemical fertilizers can increase yields so much that all village gardeners should think about using them.
Chemical fertilizers are expensive, because they are all imported.
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.
2. Groups of soils in tropical areas
Coral beach sand soils are weakly weathered, alkaline, have moderate amount of phosphorus and low amount of potassium.
Mineral beach sand soils are weakly weathered, weakly acid, and have moderate amounts of phosphorus and potassium.
Alluvial soils, near rivers or on lower slopes are weakly weathered, weakly acid or alkaline, good amounts of phosphorus and
moderate amounts of potassium.
Yellowish, brownish, reddish clays, form mainly on coral limestone.
Moderately to strongly weathered, acid, usually good amount of phosphorus, but low amount of potassium.
Reddish clays on volcanic rocks are strongly weathered, acid, low on phosphorus and potassium.
From these descriptions of the soil group you can see that most gardens may not have enough potassium in the soil.
Visit a plantation or project to see the use of chemical fertilizers.
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.
5.1 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?
5.2 Explain why these fertilizers are needed, but why 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.
6.36 Mulch saves water
See diagram 51.9: Planting banana
1. You can save soil water in two ways:
1.1 Cut down weeds and bushes that grow near your coconuts, breadfruit, vegetables or bananas.
Then the roots of these plants cannot steal the soil water.
1.2 Cover the surface of the soil around your plants with a layer of dead leaves, grass or other material.
This layer is called a mulch.
The mulch stops the hot sun from making the soil surface dry.
2. Weeds and bushes take soil water from the coconuts, breadfruit and other useful plants.
Cut down, but do not burn these weeds, because you can use them for mulch.
3. Mulch keeps the soil moist around plants.
Mulch is any light, loose covering on the soil, about 5 cm thick.
Do not dig mulch into the soil.
After light rain check that the mulch does not prevent any rain water from reaching the soil.
Old dead grass, coconut leaves and breadfruit leaves make good mulch.
4. Some ways to save soil water:
4.1 Cut down weeds that steal soil water from trees.
4.2 Put a mulch of dead leaves around young trees or vegetables.
4.3 Make mulch.
Gather dead leaves or grass and make a mulch around some young tree, e.g. a coconut seedling or a young breadfruit.
The next week, lift up the mulch to see that the soil under it is cool and moist.
Mulched Soil
1. Cooler soil
2. Damper soil
3. Less soil erosion
4. Darker topsoil (more organic matter)
5. Less evaporation from the soil
6. Less germination of weed seeds, but mulch may contain weed seeds
7. Weeds easier to pull out
8. Fewer weeds, but mulch itself may contain weed seeds
Not Mulched Soil
1. Warmer soil
2. Dryer soil
3. More soil erosion
4. Lighter topsoil, less organic matter
5. More evaporation from the soil
6. More germination of weed seeds
7. Weeds harder to pull out
8. More weeds
6.37 Electric circuit
See diagram: 32.2.1: Simple electric circuit
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.
Teach the children to set up an electric circuit to light a light bulb.
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.
5. Break open an old torch battery with the back of an axe.
Be careful!
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: Electricity conductor
Teach the children 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, items for testing,
e.g. nails, string, wood, plastic rulers, chalk, rubber, leaves.
1. Use the chalkboard 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 things have been tested, fill in the table of results on the chalkboard.
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.]
6. 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, the children should not touch them.
If you see power lines lying on the ground, you should tell people to keep away from them and you should inform local government or
the power company.
6.39 Plasticine boat sinking and floating
See diagram 6.39: Plasticine floating at deepest level
Groups of four children.
Use plasticine, jar and water.
An object that sinks can be made to float by increasing its volume so that the weight of the object is less than the weight 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 the experiment before the lesson.
This discussion can help in explaining how ships float.
Teach the children to explain why an object that sinks in water can be made to float.
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 weight 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 weight of the water pushed out.
7. Conclusion
An object floats when the weight of the object is less than the weight of the of the water it pushes away, displaces.
6.40 Hanging magnets
See diagram: 29.167: Hanging bar magnet
Teach the children 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".
Hanging magnets attract and repel
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, the poles repel each other.]
Move the south pole towards the north pole of the fixed magnet.
What happens? [They move together, the poles attract each other.]
4. Use loops of cotton to suspend two magnets freely.
Bring each pole of the two magnets close to, but not touching, each other.
Show that like poles repel and unlike poles attract.
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? [Like poles repel each other. Unlike poles attract each other.]
6.41 Electromagnets
See diagram 32.2.1: Simple electromagnet
Soft iron is used in electromagnets so the magnetism can be "turned on" and "turned off".
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.
Teach the children to make simple electromagnets.
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.]
6.42 Rain on soils
Teach the children to explain what happens when rain falls on different soils and different slopes.
Use a tin with holes punched in the bottom, different types of land, and soil in two boxes.
Practice the recommended activities of making "rain" well ahead of the lesson.
Observe slopes and erosion.
1. Let the children practice making "rain" using tins.
2. Shake the "rain" on a slope covered in grass.
What happens to the soil? [The soil is not washed away.]
3. Shake the "rain" on sloping soil containing grass, leaves and sticks.
What happens to the soil? [Some soil is washed away.]
4. Shake the "rain" on a slope of fine soil.
What happens to the soil? [Most of the fine soil is washed away.]
5. Put the boxes of different soils on slopes and shake the rain on them - sandy soil, clay soil and loam soil.
What do you see? [More soil is washed down by the rain on the steep slope.]
6. When soil is washed away, this is called erosion.
Erosion can be controlled by:
6.1 Keeping soil covered,
6.2 Not digging sloping soil,
6.3. Contour banks across slopes.
6.43 Reproduction organs, male
Be able to describe the reproductive organs of the male and describe what you do.
Use: Compound microscope, labelled drawings of male reproductive organs.
Keep to the words in the lesson and show the children these diagrams.
Do not draw your own diagrams.
1. We know that before a baby is born there must always be a mother and a father.
The mother is called the female and the father is called the male. The female animal makes the eggs and the male animal the sperm.
2. The sperm made by the male is very much smaller than the egg of the female. It can only be seen under a microscope.
A microscope makes very small things look big.
Sperm look like tiny tadpoles under the microscope.
3. Sperm are made in the testis.
There are two testes.
The sperm can get out through the penis.
Normally urine gets through the penis, but sperm can travel through it as well.
4. Discussion on sperm.
The human male produces millions of sperm in the testes.
But only can fertilize each egg.
Why are so many sperm made
6.44 Reproduction organs, female
Be able to describe the reproductive organs of the female and describe what you do.
Use: Labelled drawings of female reproductive organs, fetus and placenta.
Keep to the words in this lesson and show children the diagrams.
Do not draw your own diagrams.
1. The egg is much bigger than a sperm, but it is still very small .We can just see it.
Eggs are made in the ovary.
There are two ovaries.
2. Once a month each ovary lets an egg go down the tubes.
If the egg is not fertilized it is washed through the uterus and out through the vagina.
About two weeks later the lining of the uterus flows down and out through the vagina.
This monthly flow of blood and uterus lining is called menstruation.
3. If an egg is fertilized by a sperm the fertilized egg sticks to the lining of the uterus and the baby starts to grow.
There is no menstruation until after the baby is born.
The baby is joined by the umbilical cord to the placenta.
The placenta absorbs food and oxygen from the mother and takes away the wastes from the baby.
The placenta comes out through the vagina after birth.
6.45 Birth and care for baby
Be able to explain how babies are born and then cared for.
Use: Labelled cardboard drawings of a developing baby and associated structures, a mother caring for a new baby.
Keep to the words in the lesson and show children the diagrams, but do not draw your own diagrams on the chalkboard.
1. The baby is born nine months after fertilization.
It leaves the mother's body via the vagina.
When the baby is born the cord is still joined.
The cord is cut and died.
the cut soon heals up, but leaves a mark on the baby's body.
This mark is called the navel.
It is also called the "belly button".
2. The baby is helpless when it is born.
The mother takes care of it.
The young baby feeds on the mother's milk for a few months.
Of all the young animals the human baby is the weakest.
It is also the most helpless.
The young of other animals can walk soon after you are born.
The human baby can walk only after several months.
3. Soon after birth the baby should be put to the mother's breast to suck milk.
Breast milk is the best milk for babies and the mother should feed the baby with her milk for as many months as possible.
Bottle milk is not best for babies.
4. Animals look after your young in different ways, but all give the greatest love and care to your children.
The birth of a human baby is a joy to everyone.
The human baby is cared for not only by the mother, but by the whole family as well.
It receives food, shelter and protection from its parents.
The child also receives love and kindness from the family.