Primary Science Lessons Year 5
Updated: 2008-02-23
Please send comments to: J.Elfick@uq.edu.au
Suggested answers to the teacher's questions are shown within [square brackets].
Animals Sea animals and plants Protect sea animals Corals and jellyfish - coelenterates Shellfish - molluscs Starfish, echinoderms Fish life cycle
Food chains in the sea
Energy Water wheel
Steam wheel 		How light travels Mirror reflects light Images with a lens Water drop magnifier Pinhole camera
Human body Breathing in and out Fingerprints Body temperature Feel our pulse Test our eyesight Digesting our food
Measuring Water finds its own level Rain gauge Wind speed and direction Describe clouds Push and pull forces Air pressure
Plants Germinate bean seeds Depth of seed Germinate maize grain Roots absorb water Leaves lose water Protect our mangroves
Rocks and soils Collect rocks Soil profiles Fertilizer trial
Mineral deficiencies
 Cover crops Rain on slopes Mulch garden soil
Substances Make clay pots Make potash
from ash 		Keep water clean Heated air expands Burn to make carbon Hanging magnets

Table of contents
5.1 Sea animals and plants
5.2 Protect sea animals
5.3 Corals and jellyfish - coelenterates
5.4 Shellfish - molluscs
5.4.1 Shellfish - molluscs
5.4.2 Shellfish - molluscs
5.5 Starfish, echinoderms
5.6 Fish life cycle
5.7 Food chains in the sea
5.8 Water wheel
5.9 Steam wheel
5.10 How light travels
5.11 Mirror reflects light
5.12 Images with a lens
5.13 Water drop magnifier
5.14 Pinhole camera
5.15 Breathing in and out
5.16 Fingerprints
5.17 Body temperature
5.18 Feel our pulse
5.19 Test our eyesight
5.20 Digesting our food
5.21 Water finds its own level
5.22 Rain gauge
5.23 Wind speed and direction
5.24 Describe clouds
5.25 Push and pull forces
5.26 Air pressure
5.27 Germinate bean seeds
5.28 Depth of seeds
5.29 Germinate maize grain
5.30 Roots absorb water
5.31 Leaves lose water
5.32 Protect our mangroves
5.33 Collect rocks
5.34 Soil profiles
5.35 Fertilizer trial
5.36 Cover crops
5.37 Rain on slopes
5.38 Mulch garden soil
5.39 Make clay pots
5.40 Make potash from ash
5.41 Keep water clean
5.42 Heated air expands
5.43 Burn to make carbon
5.1 Sea animals and plants
See diagram 9.44: Seaweed - Ecklonia
Be able to name many different plants and animals of the sea.
This lesson is designed to give children an appreciation of the great variety of plants and animals in the sea. Do not teach the children the scientific classification in brackets over the page. They should list as many different types of plants and animals as possible by visiting the seashore, looking at pictures in books and remembering their own experiences. You cannot see microscopic animals, e.g. Protozoa or microscopic algae, but sometimes these plants and animals can change the colour of the sea. Bacteria are also microscopic and they cause dead plants and animals to rot. Many large animals have a bony backbone made of a glassy substance called cartilage. Porpoises, hippopotamuses and whales are not fish, they breathe air, have hair and suckle their young, so they are mammals. Seaweed plants are large algae with no roots, stems, leaves or flowers, they can be red, green or brown. Tiny floating algae or animals are called plankton. Sea grass grows on banks outside mangrove swamps. It is an underwater flowering plant.
1. Give descriptions (characteristics) and name examples of different animals in the sea, e.g. soft sponges, corals sea anemones are like flowers, tiny, long and soft worms, animals with jointed legs- shrimps, shellfish - molluscs, spiny skins - starfish and sea urchins, have backbones and skeletons - vertebrates, are plants - seaweed, sea grass, Show pictures or specimens. How many different kinds of plants or animals do you know? Draw one specimen of each kind of animal or plant.
2. Collection of dead specimens in dilute formalin solution or methylated spirit, do not kill any animals for your collection.
Animals and plants in the rivers and sea
1. Microscopic single celled animals [Protozoa]
2. Sponges (dead sponge skeletons found on beaches) [Porifera]
3. Corals, sea anemone, jellyfish [Coelenterates ]
4. Flatworms, under rocks in shallow pools [Platyhelminthes]
5. Roundworms, mainly parasites [Nematoda]
6 . Beach worms, bristle worm, tube worm [Annelida]
7 . Mosquito, diving beetle, cockroach [Insecta]
8. Shrimps, prawns, crayfish, crabs, barnacles [Crustacea]
9. Chitons, cowrie, cone shell, turban shell, ear shell, volute, helmet shell, sea slug, elephant snail, oyster, clam, mussel, squid, octopus [Mollusca]
10. Starfish, brittle star, sea urchin, beche-de-mer Echinodermata]
11. Shark, sting ray [cartilaginous fish] Perch, eel, sea horse [bony fish]
12. Frog, toad [Amphibia]
13. Snake, turtle, crocodile [Reptilia]
14. Sea gull, tern, frigate bird [Aves]
15. Hippopotamus, porpoise, whale [Mammalia]
16. Plants in the rivers and sea, Green, red and brown seaweed [Algae] Ferns [Pteridophyta] Raphia palm, sago palm [Gymnosperms] Mangroves, rushes, grasses [Angiosperms] Bacteria and fungi (cause rotting)
5.2 Protect sea animals
See diagram 9.307: Turtle
Be able to explain why you should treat sea animals as a renewable resource.
Use conservation campaign posters for a particular country. Before this lesson, think of some local examples of loss of natural resources, e.g. inshore fish.
1. Explain the meaning of the word "resource" to the children. It means something you can use when you need it. A forest is a resource for fuel wood. A river is a resource for stones, clay and minerals such as gold.
2. If a resource can keep producing something that you need, you say it is a renewable resource. A forest is a resource for fuel wood for many years provided you do not cut down all the trees. Stones, clay and minerals are not renewable, once you take them away they are gone. Living resources are renewable, a garden is a living resource that can produce food year after year.
3. Non-living resources are not renewable. Living resources are renewable if you use only some of it and let the rest grow and reproduce.
4. The animals in the sea are one of your greatest living resources. For a long time in the past people have eaten only some animals and let the rest grow and reproduce. The animals have remained a renewable resource.
5. Nowadays people catch too many sea animals. If you catch too many animals such as fish, porpoise and crab there may not be enough left to renew the resource. You should take just enough for your needs but let most sea animals grow and reproduce. Otherwise they will become a non-renewable resource and die out. This will be a great loss to future generations in your country. Recent government efforts in many countries focus on campaigns through various establishments and institutions to do and ensure systematic conservation of natural resources.
5.3 Corals and jellyfish - coelenterates
See diagram 9.305: Corals and jellyfish - coelenterates
Be able to identify these animals and explain that they all have the same basic structure.
Use different coral specimens and pictures or specimens of sea anemones and jellyfish. You can teach this lesson on a coral reef or in the classroom.
1. If you have seen pieces of coral and a coral reef. Explain that coral is made up of many tiny animals each of which has a coat of hard lime. The lime coats stick together to make the pieces of coral and the coral reef. The coral animals die leaving the dead coral made of lime. Show pieces of coral. Is it alive? [No.] Where did the coral animals live? [In the holes in the dead coral.] Can you name different kinds of coral? The coral animals are so small you cannot study them.
2. However, sea anemones are much larger, have soft bodies and are similar to coral animals. The sea anemone has three main parts: 2.1 tentacles that can catch food, 2.2 mouth, 2.3 stomach. Tentacles can kill small fish by stinging them with poison. Can you put a finger in a sea anemone's mouth? Sea anemones are called the "flowers of the reef" because they have bright colours. They live in rock pools and catch animals with their tentacles. Sometimes they pick up shells so they can hide. Sometimes there is a friendly fish that swims among the tentacles and does not get stung.
3. A jellyfish does not look like a sea anemone or coral animal, but it does have the same three parts: tentacles, mouth and stomach.
4. Look at the drawing of the coral animal cut open. Turn it upside down. Imagine the soft body swelled up with jelly. Now you have a jellyfish. Jellyfish float in the sea. They can sting fish with their tentacles then eat them. Jellyfish can sting people. Some of them glow at night. They swim very slowly.
5.4 Shellfish - molluscs
See diagram 9.305: Shellfish - molluscs
Be able to describe and name different kinds of molluscs, shellfish and land snails.
Use examples of molluscs, shellfish and land snails. Collect different kinds of shells or shellfish and land snails. You can also prepare the class for an excursion to the coral reef. A live land snail or a shellfish in a jar of sea water will interest the children. Little land snails (Limocolaria) can be collected at night or early in the morning. Shellfish are called Molluscs.
1. If you know an animal that has a soft body and carries its house on its back. [A land snail or sea snail.] Explain that their body is divided into three parts: head, foot and coiled stomach. The head has a mouth and eyes at the end of tentacles. The body can be pulled into a coiled shell. Sometimes the house has a door made of hard shell. They can move along using their big foot.
2. Snails are one kind of animal called molluscs. There are four different kinds of molluscs:
2.1 Snails, have a single coiled shell, e.g. land snails, cowries, ear shells, cone shells, auger shells, helmet shell, volute, baler shell, scorpion shell. Some have lost their shell, e.g. land slugs and sea slugs.
2.2 Chitons have flat plates instead of a shell, a small head and a big foot.
2.3 Bivalves have two flat shells joined by a muscle that can close them together, like clapping hands. Some can use the foot to burrow in the sand, e.g. scallop, cockle and muscle. Others are fixed in one place, e.g. oyster, clam.
2.4 A squid and octopus foot is divided into eight arms. They can swim by squirting water out backwards. The squid has a small internal shell and the octopus has no shell. How many kinds of molluscs can you find?
Extra Activity: Make a shell collection and name the types of shells from different localities.
5.4.1 Shellfish - molluscs
Be able to classify shells into groups based on observed similarities and differences.
Collect different types of shells and tell the children to bring some.
1. Give each group a pile of mixed shells.
2. Sort the shells into small groups. You must say why you put shells into a particular group. Do not tell the children how to do it. Let the children decide their own groupings.
3. Pick out one shell from a group. Why did you put it into that group? [Some possible answers: they look the same, same colour, same shape, same markings etc.]
4. Do you know the common name for each group? [Some examples include scallop, top shell, cone shell, snail shell, cowrie, clam.]
5. Arrange the shells in each group in order of size.
6 . Draw the medium-sized shell of each group in your book.
Extra Activity: Make a collection of shells for the class. Label the shells with common names.
5.4.2 Shellfish - molluscs
Be able to explain why you should protect shellfish.
Shellfish are molluscs. Molluscs have a body divided into three parts: head, a large foot, and coiled stomach in a shell. In this lesson the teacher should explain that shellfish are interesting animals that are part of the natural heritage. If they are all killed because more people are eating them or selling the shells then something that you all own would be lost. Some shellfish appear on postage stamps: Cowrie, Trochus, Glory-of-the-Sea, Bailer Shell, Pearly Nautilus, Conch, Venus Comb (Murex) Triton.
Shellfish are valuable for four reasons:
1.1 They are part of the food web, plants and animals depend on each other for food and shelter. These plants and animals have lived in the local natural environment for a long time because there is a balance of numbers. If you kill too many of one kind of plant or animal, you upset the balance and other plants and animals will be affected.
1.2 They are a source of valuable growth food. Yet the human population is increasing rapidly and some kinds of shellfish on the coast could all be eaten.
1.3 They are a source of money. Some shells such as Cowrie, Trochus and Glory-of-the-Sea can be sold to overseas buyers. Also tourists like to buy shells to remember the country they have visited.
1.4 They are a part of your natural environment for all people to look at and enjoy. These shellfish are part of your culture and history. your ancestors were famous for the inlay work in carvings using Pearly Nautilus shell, if all these shellfish were killed this traditional art work would be lost.
and group display of shells - Before the lesson, tell the children to bring some shells.
1. Show the children the shells and pictures of shells. How many different kinds are there? Do you know their names? How are shells used at home? Do people eat them? [Yes.] Do people use them? [Yes, e.g. Baler Shell.] Do people sell them? [Yes, to tourists.] Do people make anything with them? [Yes, Mother-of-pearl inlay work for traditional decoration and to sell to tourists.]
2. Explain how shells are part of your natural heritage. They are something your ancestors owned, something you own, and something that should be still living for your children. 3. Explain the four reasons why shellfish are valuable for the:
1. food web
2. food
3. money in culture.
4. Explain why shellfish could all be killed: 4.1. There are more people now than before. 4.2 There are more canoes with outboard motors and people with diving equipment. 3. There are more people want to sell shells. 4. There are more foreign boats and tourists.
5. Explain how children can protect shellfish
5.1 Tell people about the importance and the danger of killing too many shellfish.
5.2 Tell children to watch foreign boat crews and tourists.
5.3 Not to kill the shellfish unless very hungry.
Extra Activity: Display of shell under the heading "Our Natural Heritage"
5.5 Starfish, echinoderms
See diagram 9.304: Starfish, echinoderms
Be able to identify and list the different types of echinoderms.
Use drawings and preserved specimens of types of echinoderms. The spiny skinned animals, called echinoderms are found only in the sea. They have a circular design, if you cut through the centre of their mouth in any direction the two halves look the same. Beside having spines in their skins or spines sticking out, they have hundreds of little tube feet to help them move along the bottom of the sea. The starfish usually has five arms and a mouth facing down. They can suck on to the shell of a bivalve mollusc such as an oyster, pull open the shells then eat the inside. Brittle stars have a separate round body and long legs that they can drop off when they are frightened. Sea urchins are globe shaped, have long spines and downwards facing teeth that can grind a hole in a shellfish. Beche-de-mer is an example of the sea cucumbers that have lost their spines. When frightened they spit out their stomach. Beche-de-mer or trepang is exported overseas for Chinese soup. Use specimens or pictures of these animals. The following groups of spiny skinned animals are called Echinoderms: 1.1 starfish, 1.2 brittle stars, 1.3 sea urchins, 1.4 sea slugs, 1.5 sea cucumbers, e.g. beche-de-mer.
1. Show drawings or specimens of these animals. What are their common features? [Shape, spiny skins, live on the sea bottom.]
2. Look at the starfish. Does it have a front or back? [No.] Are the arms different? [No.] How does it move? [With its tube feet.] What are the arms for? [To pull apart the shells of shellfish.]
3. Draw each different kind. The aim is to perfect observation and creativity in them.
Extra Activity: Collection of dead echinoderms, do not kill any animals on the reef.
5.6 Fish life cycle
See diagram 9.301: Life cycle of a fish | See diagram 9.302: Shark and fish
Be able to explain the life cycle of a fish.
Use illustrations of the life cycle of a fish. Bring some freshwater fish to class.
Show the diagrams of the life cycle of a fish to explain the following points:
1. A female fish lays eggs in the water and a male fish puts many sperm into the water near the eggs.
2. many eggs are not fertilized.
3. Only those that are fertilized become little fish.
4. Many little fish are eaten, so only a few grow into adult fish.
5. The female fish must lay thousands of eggs if some are to grow into adult fish.
Extra Activity: Examine closely the adult fish. Can you see any differences between the male and female fish Can you draw the differences?
5.7 Food chains in the sea
Be able to explain the importance of keeping the food chains in the sea unbroken.
Use plants and animals in the environment and in the sea. In this lesson children should understand that all plants and animals in the sea are important because they are related by food chains. Plants and animals depend on each other for food and when they die their bodies are rotted by bacteria to be used by simple plants and animals again. You can think of the food chains usually or by particular examples. An example of a food chain is seaweed is eaten by a shellfish is eaten by a fish is eaten by a bird. Seaweed Shellfish Fish Bird When each of these animals dies, the material in their bodies decomposes and can be used by the seaweed again. However, if you eat all the shellfish or fish then the food chain is broken. Usually plants are eaten by animals are eaten by larger animals are eaten by larger animals. If ">>" means "is eaten by", you can show a food chain as: plants >> small fish >> big fish >> shark >> man
If you kill all the animals or plants in any step of the food chain then the food chain is broken and all the living things in the food chain are affected.
1. Give examples of living things in the sea eating other living things, e.g. smaller fish eaten by sharks. Write all the examples on the chalk board. So far you have steps in the food chain, tell the children to tell you a third or fourth step, e.g. seaweed, fish, shark, man.
2. Can you make different food chains? Can you make food chains with many steps? Try this with the children and write the steps on the chalk board.
3. What is passed along the food chain? [The material in the bodies of the plant and animals.] What happens to the materials when the plants or animals die and are not eaten? [They rot.] Is the material of their bodies lost from the food chain? [No, simple plants and animals can use it again.]
4. Show the general food chain. Plants fish one fish two shark
5. The dotted lines show the bodies of dead plants and animals made rotten by bacteria then used by plants again. What would happen if you caught all the fish? [There would be no food for fish two and later no food for the sharks. The food chain would be broken.]
6 . Name any kinds of animals or plants in the sea that could be wiped out by too much fishing or hunting. How many animals of the sea should you catch? [Catch some but do not catch so many to break the food chain.]
Extra Activity: Discussion with an old fisherman or fisheries officer on whether there are as many fish now as before. Are some food chains already broken? Visits to agricultural departments (fishery section) can help us to find out more about this.
5.8 Water wheel
See diagram: 9.3.2
Be able to make a water wheel and show how moving water can turn a wheel.
Use water, hose, or water in a bucket. The wheel can be made in any of the following ways:
1.1 Use thin bamboo, with thin pieces of tin or cardboard for the blades and a smooth stick for an axle.
1.2 Use pawpaw stalks instead of bamboo with a smooth stick for an axle.
1.3 Cut a small square of coconut husk. Make a hole in the middle with a hot nail. Push the pieces of tin in the sides. Let it spin on the nail or a smooth stick.
1.4 Cut a round piece of paper or taro stem. Stick very stiff leaves round the edge. Spin on a smooth stick.
1.5 Stick Plasticine (modelling clay) around a piece of bamboo. Stick cardboard or tin pieces in the Plasticine. Spin on a smooth stick.
1.6 Use an empty cotton reel and tin sheets. Spin on a nail.
1. Give out the materials and show how to make their water wheels.
2. Put the wheel in running water under a tap or by pouring water over it. What happens? [The wheel turns when the water hits the blades.] Increase the speed of the water. What happens to the water wheel? [It turns faster.]
3. What happens when the wheel is placed in running water. [It turns or spins.] What happens if you increase the speed of the water? [The wheel turns faster.] How can you increase the speed of the water? [By opening the tap more, by making the water fall further.]
4. Collect the water wheels and keep them for the lesson on Steam Wheels.
Extra Activity: Water wheels are used to generate hydroelectricity. the electrical generator is often placed at the bottom of a water fall and water is lead to it in a pipe from the top of the waterfall.
5.9 Steam wheel
See diagram: 9.3.3
Be able to show that steam can turn wheels.
Use water wheels from previous lesson on water wheels. Cans with tight fitting lids with a small hole in the lid. Burners, heating stand and water. Make the holes in the tin lids with a nail. Do not put too much water in the tin as it will take too long to boil and produce steam. About four cm should be enough.
1. Give out the materials and tell the children to pour water into the can and then fit the lid on tightly. Place the can of water on a heating stand. Light the burner and heat the water.
2. When the water is boiling tell the children what is coming out of the hole in the tin lid. [Steam.]
3. Take it in turns to hold your water wheel over the hole in the lid as shown in the diagram.
4. What happens? [The wheel turns.]
5. What is formed when water boils? [Steam.] What causes the wheel to turn? [Steam.] Which can turn a wheel faster, water or steam? [Steam.]
6. The wheels of a steam engine are turned by steam. Steam engines are used to make electricity, drive trains and boats. Wood or coal is burnt to heat water to produce the steam. Steam boats and trains are not common now. However, in many countries most of the electricity is made from burning coal in steam engines that turn on electric generators.
Extra Activity: Draw pictures of steam engines used in boats, trains and power stations.
5.10 How light travels
See diagram: 28.1.1.5
Be able to show that light travels in straight lines.
Use 3 pieces of cardboard about 25 cm x 25 cm for each group, candles or a torch or a mirror to reflect sunlight, jar of water, chalk dust, piece of string, rubber tubing or pawpaw petiole about 50 cm long. Light is invisible, it cannot be seen. Completely transparent substances, like air it also cannot be seen because you allow all light to pass through them. You cannot see light passing through air or water unless the air or water has something in it, e.g. chalk dust, street dust that will reflect the light into your eyes
1. Use a pin to cut a hole in three pieces of cardboard. Hold each piece of cardboard about 10 cm apart. Thread a piece of string through the holes and pull very tight. Place a candle in line with the string. Take away the string and tell the children to look through the hole at the candle.
2. Can you see the candle? [Yes.] What would a line from your eye through the holes to the candle look like? [A straight line.]
3. Move one piece of cardboard. Can you see the candle? [No.] Why not?
4. Put some chalk dust in a jar of water. Shine some light through it. How does the light travel? [In a straight line.] Can light bend? [No.] Can light go around corners? [No.]
Extra Activity: How can you see around corners With a mirror, the light still travels in a straight line.
5.11 Mirror reflects light
Be able to show how light travels when it is reflected by a mirror.
Use mirrors, cardboard and scissors, shiny surfaces, e.g. aluminium foil, tin lids, rubber ball. Practice before the lesson with the recommended materials.
1. Give out two mirrors and different shiny surfaces to each group. 2. Use a mirror and shiny surfaces to reflect a beam of sunlight along the floor, or the ground or along the top of a desk. Which things reflect the light best? [Materials with smooth shiny surfaces.]
3. Use scissors to cut a slot out of your piece of cardboard, to put the slot over the beam of light.
4. Turn the second mirror to reflect the thin beam of light to the left, to the right, up and down.
5. Tell one child to stand against a wall holding the second mirror to the chest. Another child should reflect light on to the second mirror from the first mirror. A third child can then see the reflected light. Tell another child to throw a rubber ball from the first mirror at the wall behind the second mirror. Where the ball goes. [It bounces off the wall in the same direction as the light.] Reflection occurs when light bounces off shiny surfaces.
Extra Activity: Place two mirrors at right angles and a bottle top between. How many reflections are there?
5.12 Images with a lens
See diagram: 28.1.1.5
Be able to form an image on a screen using a lens and can describe the image and measure its distance from the lens.
Use candles or flame, white paper for screens, you can rub some cooking oil on the paper to make a better screen, magnifiers. You should darken part of the classroom. Formation of images on screens and distance measurement are the real focus of this lesson.
1. Put the candle, lens and screen in a darkened area so that the image of a candle can be seen on the screen. Place the lens at 10 cm from the screen to get the sharpest image.
2. Describe the image. [Small and upside down.] What happens when you move the lens closer to the candle? [The image gets larger and is still upside down.] When the size of the image is about equal to the size of the candle flame. [When the lens is about half way between the screen and the candle.]
3. Look at images of objects outside the classroom. Describe them. [The images are smaller than the objects and they are upside down.]
4. Lenses are found in eye glasses, cameras, binoculars, projectors.
Extra Activity: Where is the screen in your eye? [The screen is at the back of the eye, the lens is at the front of the eye where light enters. So in your eye the distance between the screen and the lens stays the same.]
5.13 Water drop magnifier
Be able to make a water drop microscope and use it to describe the structure of small objects.
You need a piece of cardboard and a piece of sticky tape. Punch a hole through the sticky tape and the cardboard. Put a drop of water on the hole to make a water drop microscope. To use the microscope attach it to a ruler at with sticky tape, put some hair or a leaf on the paper, look down through the water drop and move the pencil between the book and paper.
1. Show the curved surfaces of their magnifying lenses. [Glass with a curved surface can magnify, make things bigger.] that you are going to make a curved shape out of water, a kind of lens.
2. Show how to make the water drop microscope. Show how to set up the water drop microscope. Look at the shape of the drop very carefully.
3. Put a small printed word under the water drop microscope. Write this word at the size you see it.
4. Move the microscope up and down. Focus it until the printed letters look bigger. The children may have to remove a little water from the drop with their fingers until the printed letters look bigger.
5. Put a little bit of sugar on their paper. Spread the sugar under the microscope and then observe it.
Extra Activity: Look at different things using your microscope, e.g. soil, ants, roots, feathers.
5.14 Pinhole camera
See diagram: 28.9.0
Be able to make a pinhole camera and describe the difference between the image and the object.
Use paper screen, nearby objects. Make a pinhole camera before the lesson. An image is the picture of an object on a screen. The image of a pinhole camera on a screen is upside down.
1. Show your pinhole camera.
2. Make a small hole in the bottom of the tin using a nail. Cover the open end of the tin with a piece of thin paper, e.g. typing, tracing or greased paper. This is the screen on which the picture will be formed. Use a rubber band or a piece of string to hold the paper on the tin. Tie a piece of newspaper around the tin to form a tube. This makes the screen dark. The picture is easier to see in the dark.
3. When the children have made their pinhole cameras tell the children to point them towards the door or windows. Let the children look at trees, buildings etc. through their pinhole cameras.
4. This is how a real camera works except that the paper screen is the film covered with light sensitive substances.
Extra Activity: Measure height of object / height of image, and distance from object to pinhole / distance from pinhole to screen.
5.15 Breathing in and out
Be able to observe what happens to your bodies when you breathe in and out.
Use a watch with a second hand, bucket with a handle. This lesson is designed with two aims:
1.1 To give children more experience in observing their breathing mechanism and so be able to improve observation of their own bodies.
1.2 To learn about the importance of oxygen gas (O2) to the body. Use a watch with a second hand or you could count seconds "one and two and three and four".
1. Sit quietly watching you. What they are doing? [Nothing, they are just sitting still.] They are not doing anything. They are breathing in and out. Did they realize they were breathing? [No.] What made them breathe in and out. [You don't know.] Your brain makes you breathe in and out. They don't have to think about it. It is automatic.
2. Sit quietly watching you. Tell the children to close their mouths, hold their noses and stop breathing. They will count to 100, then they can start breathing again. Give the order and start counting. When do they start breathing again? [After 20-30 seconds.] Why they didn't wait until the count of 100. [You had to breathe again.] What made you breathe again? [The brain.]
3. Breathe in and out very deeply 20 times. Then say "Stop" and start counting. How long can you hold your breath now? [About one minute.] Why can you hold your breath longer? Explain that when you breathe in and out your body takes in oxygen gas from the air. your body needs oxygen gas. If you breathe in deeply your body stores some oxygen gas in the lungs so you can hold your breath longer.
4. Push one finger up under the lowest right rib. Breathe deeply in and out. What happens to their ribs when you breathe in? [They rise.] Show the bucket. If your rib is like the handle of the bucket, when you breath in it is like raising the handle of the bucket. When you breathe out, the handle of the bucket goes down. Feel up under your ribs again and breathe in deeply. What happens to your finger when you breathe in? [It is pushed down.] What pushes it down? Explain that a big muscle called the diaphragm pushes the finger down. If you run a long way, you may get a pain in your diaphragm called a "stitch".
5. If the chest gets bigger or smaller when you breathe in. [Bigger, the chest expands.] What part of the chest moves? [Two parts, the ribs turn up like a bucket handle and the diaphragm pushes down.] When you breathe in where does the air go? [Into the lungs.] Where are the lungs? [There is one on each side of your chest.]
6. Why do you breathe in air? [Our body needs oxygen gas.] At the start of the lesson why were you breathing quietly? [You do not need much oxygen when you are sitting quietly.] What happens to your breathing when you start running? [You breathe in and out more quickly and deeply.] Why do you breathe more when you are running? [The body needs more oxygen gas.]
Sentence Completion: your body needs [oxygen] gas. When you breathe in, your body gets oxygen gas from [the air]. You breathe [slowly] when you are sleeping or sitting quietly because you do not need so much [oxygen gas]. When you are running, you need much oxygen gas so you breathe [quickly].
Extra Activity:
1. Breathe in and out rapidly through your nose and through your mouth. What do you notice? [The nose warms the air before you breathe it in.]
2. Close your mouth and hold your nose then try to breathe out. What do you notice? [Pain inside the ear.] This is the air pressing against skin in the ear called ear drums. If you swallow, the pain will go away. They may feel this pain when you are in a landing aircraft.
5.16 Fingerprints
See diagram 9.233: Fingerprints
A. Be able to describe their fingerprints.
You will need a stamp pad, magnifiers soap and water.
If you do not have a stamp you can use carbon paper or make carbon paper from aluminium foil:
1. Use a piece of aluminium foil or silver paper. 2. Hold it in a candle flame so that the lower side becomes covered evenly with a layer of carbon. 3. Test the carbon foil you have made. It is like carbon paper. You can use it to make fingerprints.
1. Look at the skin on your finger tips. There are lines on them. Look for lines with the shapes in the diagram: whorl, loop, arch
2. Make a print of your thumb use a stamp pad or pour some ink onto absorbent. Press your thumb onto the inky paper. Wet it all over with the ink. Then press your thumb onto a sheet of clean white paper.
3. Look carefully at the thumb print. Look for arches, whorls, and loops.
4. Look at the thumb prints of other children. Are any prints the same? [No] Police use finger prints to identify people.
Extra activity: Lengths of fingers
1. Measure the lengths of your fingers as shown in the diagram. 2. Calculate the ratio: length of middle finger/length of little finger.
3. Is this ratio the same for all children? Is it the same for boys or girls?
B. Be able to describe and compare fingerprints among human beings.
Use ink or stamp pads, magnifying glass. This lesson is designed to train children in the skills of description and comparison. Also it is interesting because police use fingerprints to identify people. No two people in the world have the same fingerprints.
1. Explain how police use fingerprints. If a robber breaks into a house he leaves invisible fingerprints on anything he touches, e.g. door handle. The police can put a special powder on the door handle and record the fingerprints. Later the police can catch a man who could be the robber. The police put ink on the man's fingers and take the fingerprints. Then they compare the man's fingerprints with those they took off the door. If the fingerprints match then the police have caught the robber.
2. Give each group some ink or a stamp pad. Put the ink on the thumb then press the thumb on the paper. Hold the fingerprint up to the light and look at it with a magnifying glass.
3. Fingerprints can be described: 3.1. whorls, 3.2. loops, 3.3. arches
Draw the outline of your thumb. Draw in the whorls, loops and arches.
4. Make fingerprints of your other fingers. Do they have the same pattern as your thumb? [No.]
5. Compare the fingerprints of different children. Are they the same?
Extra Activity: Fingerprint Game: Each child in the group makes two sets of fingerprints. The teacher takes one set, then gives back one print of the "robber". Now compare the "robber's" fingerprint to all the fingerprints. Who is the "robber"?
5.17 Body temperature
See diagram 22.02: Clinical thermometer
Be able to measure the temperature of your body using a clinical thermometer.
Use a clinical thermometer. You must use a clinical thermometer and not any other type of thermometer. You will also need a glass of water with some antiseptic in it. Make sure that you can read the thermometer. Normal body temperature is marked with an arrow of 37oC. In a clinical thermometer there is a constriction in the bore. This allows the mercury to expand (rise) showing a rise in temperature but it does not allow the mercury to contract (fall) again. This lets you take a thermometer out of a patient's mouth and does not give a falsely low reading. To move the mercury down again you have to flick the thermometer with a quick turn of their wrist. Practise flicking it to make the mercury go down. Do not drop it on a concrete floor. Practise flicking the mercury down standing on the grass. Do not be alarmed at small differences in temperature between people. In women, the body temperature changes with the menstrual cycle.
Take the temperature of each child in the class.
1. Show the clinical thermometer. Have they seen it before? Explain that this measures how hot your body is. In healthy people the body has a constant temperature: 37 degrees Celsius (37oC) but it can vary slightly. It is lower when you wake up and it is higher if you run about a lot. If the body temperature is much higher or lower this means that you are sick.
2. Draw the scale on the chalk board.
3. Take your own temperature. Draw an arrow on the chalk board diagram to show your own temperature, e.g. 37.2oC.
4. Flick down the mercury. Wash the thermometer in antiseptic then read the temperature with each child. Tell each child to draw an arrow on the chalk board to show your temperature.
5. Look at all the arrows. What conclusion? [The average temperature is 37oC, some temperatures are a bit higher or lower.]
Extra Activity: Compare these two groups of temperature readings:
1. Adult / child / babies
2. Boys / girls
3. Lying down after running around the classroom. Make a table and compare your readings for each group. Besides this you could try outside the class by going to a nearby Health Centre or hospital to collect information on temperature readings.
5.18 Feel our pulse
See diagram: 9.239.1
Be able to feel your pulse and notice how it changes with different body activity.
Practice feeling your own pulse. How many beats of your pulse per minute? [About 70.]
1. Children must be seated quietly and not move about.
2. Put your forearm on the desk, palm up with the wrist on the edge of the desk and hand in the air.
3. Press the four fingers of the other hand down on the side of the wrist. Wait a little while, keep still, and you will feel the pulse. Start counting the pulse.
4. Now tell the children to run around the classroom and feel the pulse again. [It is faster.]
5. The pulse tells us how fast the blood is pumped around the body. If you are sick or after a big meal it is faster, when you are asleep it is slower.
6 . Roll up some paper to make a tight tube. Hold it against the chest of another child. Press your ear against the other end. Can you hear the heart pump the blood?
Extra Activity: Use a watch to tell the children when a minute starts and stops. Write down your pulse rates on the chalk board in beats per minute. What is the average pulse rate?
5.19 Test our eyesight
See diagram: 28.1.1.6
Be able to test your eyesight.
This lesson is designed to give children experience in measuring eyesight and comparing the eyesight of different children. It is different from the eyesight test used by doctors. Use the "E" chart over the page. Cut out a big "E" from a piece of cardboard or tell the children to cut out the big "E" during the lesson or the children can make an "E" shape with their fingers.
or groups of four
1. Draw a line on the floor five metres from the teacher's chair and parallel to the front of the teacher's desk. Stand on the line facing you. Show the chart. Point to the top E. The child has to hold the E in the same position or make the same E shape with the hand.
2. What is the lowest line in the chart where the child can see the positions of the E? If you can see the bottom line, you should move one metre away and start again. If you can't see the bottom line, you should move one metre closer.
3. Test all the children again. Which child has the best eyesight?
4. Do the test again with one eye closed, then test the other eye. Is one eye stronger than the other?
Extra Activity: Draw a chart of white E's on a black background. Are they easier to see or harder to see than the black E's?
5.20 Digesting our food
Be able to observe and discuss what happens during digestion by examining an animal's stomach.
Use food, chicken or rat, scissors and knife, chloroform solution and lens. The teacher has to recall the methods of studying internal organs of animals by means of dissection.
1. Digestion of food is in two stages:
1.1 Break down of food into smaller parts using teeth and tongue in the mouth.
1.2 Softening of the food by saliva in the mouth and acid in the stomach.
2. Let the children bite a dry biscuit. Their teeth and tongue will break it into smaller pieces. Soon it tastes sweet because the saliva changes starch into sugar.
3. Kill a chicken or toad and show the stomach. It is like a bag made of hard muscle. This muscle can mix the food with acid. 4. Cut open the stomach with scissors. Turn the stomach inside out and show the digested contents.
5. Wash out the inside of the stomach and let the children examine it with a magnifier. Can they see the folds in the walls?
Extra Activity: Show the inside of a cow's stomach called tripe. You can buy this in a butcher's shop. Compare the size with the stomach of a rat or rabbit.
5.21 Water finds its own level
See diagram 12.0.0: Water levels
Be able to show that the surface of water is always horizontal.
Use plastic tubing, ruler or metric stick, hose, water. The depth of liquid in a vessel remains the same and does not depend on the shape of the vessel containing it.
1. Give out empty plastic tubes, water and rulers. Pour some water above the desk in each arm. What the difference is in height? [No difference.] Pour some more water in and measure again. What is the difference? [No difference.] Draw a tube showing the level of the water and the horizontal line joining the level.
2. Hold one arm of the tube vertical then move the other arm apart keeping it vertical. What happens to the height of the water in each arm? [It drops a bit.] Compare the height of the water in each arm. [They are the same.]
3. Keep one arm of the tube steady, then bend down the other arm. What happens to the height of water in each arm? [The height drops the same in each arm of the tube.]
4. Put your finger over the left hand end of the tube. Then bend down the right hand end. What happens to the water level? [It goes down as you bend the tube.] What happens to the water level in the left hand tube? [It does not change.] Are the levels still the same? [No.] Why not? [The finger in the left hand end blocked the tube so no air can get in or out.]
5. Go outside on a slope. How you can find two places at the same level? [Use two rulers and the hose or long plastic tube.] B is five cm lower than A. A is five cm higher than B. [if the height of water in the tube is 10 cm at A and B, what is the difference in height at A and B? [The same height.] If the height of water at A is 10 cm and at B is 15 cm, what is the height at A and B? [B is five cm lower than A.] If the height of the water at A is 10 cm and at B is five cm, what is the height at A and B? [B is five cm higher than A.]
6 . Using this tube, you can mark a horizontal line around a hill or along a slope. This line is called a contour. Mark a contour line along a slope.
Extra Activity: Making contour banks to prevent soil erosion. Mark a contour line along a slope or around a hill. Dig a drain at the same depth along the contour line and use the soil to make a contour bank on the down side. Pour some water in the contour ditch. It should not flow along because the bottom of the ditch should be horizontal. The water should just spread out. Contour ditches and banks can stop soil being washed down by the rain. You can stop soil erosion. If the height of the stick at A is three metres and at B is 1. 5 m, how does the ground slope A From B to A? [B is 1. 5 m above A.]
5.22 Rain gauge
See diagram: 24.4.5
Be able to read a rain gauge and record the rainfall each day.
Use a rain gauge, glass jar, rain chart
Table of average rainfall in two places: Honiara and Avu Avu
Month Honiara Avu Avu
January 249 262
February 234 225
Total Rainfall 2195 5787
Number of wet days 195 222
The site selected for a rain gauge should be level ground not near fences or trees. Attach the bracket to a post about 1.5 metres above ground in a vertical position. Rainfall should be measured at 9.00 a.m. daily and the amount entered on the rain chart against the date of the previous day. To read the gauge, remove the plastic gauge from the bracket, take it to the chart, read the scale to the nearest millimetre (mm) record this on the chart, read the scale again and pour out the water. Replace the scale in the bracket. If you do not have a rain gauge, you use a glass jar on a post. Measure the depth of water in mm. This reading in mm will not be the same as a proper rain gauge in mm. Use a rain gauge or glass jar, rain chart on the wall (see over) or special rain recording book, ruled as in rain chart.
Each child must read the rain gauge.
1. Show the rain gauge or jar and ruler. Show how to read the gauge with water in it, hold the top of the gauge between thumb and first finger, hold it vertically, level of water should be opposite their eye, keep their back straight, read level of water to nearest mm.
2. Read the gauge but do not tell the children the reading. Pass it from child to child, read the gauge and write down the reading. When you have finished, ask the children to tell the class their readings.
3. Show the rain chart. Show how to write in it.
4. Go outside to the rain gauge position. Is it near trees or buildings? Show how to read the rain gauge at 9.00 a.m. each day and record it on the rain chart.
5. Draw up a roster of children to read the rain gauge each day, two children each day.
6 . Ask the children if they have heard rainfall measurements announced on the radio. If used properly, the rain gauge method is the same as that used by government officers who measure rain.
Rain chart mm Jan
 mm Feb
 mm Mar
 mm Apr
 mm May
 mm Jun
 mm Jul
 mm Aug
 mm Sep
 mm Oct
 mm Nov
 mm Dec
22 - - - - - - - - - - - -
23 - - - - - - - - - - - -
Totals - - - - - - - - - - - -
No. days - - - - - - - - - - - -
Totals since 1 Jan 2 months 3 months 4 months 5 months 6 months 7 months 8 months 9 months 10 months 11 months 12 months
Extra Activity: Record the readings from the chart on to a bar graph. In this graph below notice the difference in rainfall pattern between the north west coast and the east west coast of Guadalcanal. What results are given by similar activities in your own district?
5.23 Wind speed and direction
Be able to make regular recordings of wind speed and direction, and then summarize the observations.
Use a compass directions, a direction chart. This lesson is designed to give children the experience of making regular observations of the natural environment using inexact measurements. Use to set out the compass directions in the playground and make a wind speed and direction chart for the wall.
Wind speed and direction chart, Place: Honiara, Month: January, Time: 9.00 a.m., Wind speed: calm, light, moderate, strong, very strong, total, Wind direction: N north = 3, NE northeast = 0, E east = 0, SE southeast = 2, S south = 16, 16 SW south-west = 10, W west = 0, NW northwest = 0, Total = 31
Wind speed Calm Light Moderate Strong Very Strong Total
Direction . . . . . .
N 3 - - - - 3
NE - - - - - -
E - - - - - -
SE - 1 1 - - 2
S - 8 7 1 - 16
SW - 5 5 - - 10
W - - - - - -
NW - - - - - -
Total 3 14 13 1 nil 31
Wind speeds Description of what you see and feel
Calm Smoke rises straight up, no wind at all
Light You can feel wind on your face, leaves move on the trees
Moderate Raise dust and paper, small branches move on the trees
Strong Trees sway, whistling sound in telegraph wires
Very Strong Twigs break off the trees, you find it hard to walk against the wind
Each class must estimate wind speed and directions.
1. Explain that it is important to know the pattern of wind speed and direction so people can predict the weather. For example in January at Honiara you can expect light to moderate winds coming from the south or south-west. This information helps us to understand the weather and is useful for aircraft pilots and captains of ships.
2. Direction game: Line the children facing north. Hold your arms horizontally pointing your fingers. Pretend this is the direction of the wind. What is the direction of the wind? [Southerly.] Turn around facing south and hold your arms up. What direction is the wind? [North.] Call out different wind directions. The children have to point their arms in the wind direction. East wind, point west, west wind, point east, south-west wind, point northwest, north west wind, point south east.
3. Wind Speed Game:
4. Describe the present wind speed and direction and record it on the chart. Divide the class into pairs. At 9.00 a.m. each day each pair has to record wind speed and directions.
Extra Activity:
1. What happens when a cyclone comes? [Strong wind in one direction, then calm, then strong wind in opposite direction.]
2. Beside the 9.00 a.m. reading observe wind speed and direction at 3.00 p.m. Is there a pattern of difference between the 9.00 a.m. and 3.00 p.m. observations? For example at Honiara in January the afternoon winds are usually lighter than the morning winds and swing from between S and SW to between N and NE. A similar observation and exercise should be carried out in your own area of the country.
3. Trade winds are winds that blow regularly in one direction, sometimes for six months, and are used for trade by sailing vessels. In the Northern hemisphere they blow from the north east and in the Southern hemisphere they blow from the south east, about 30o each side of the equator.
5.24 Describe clouds
See diagram 4.143: Different clouds | See diagram 4.135: Cloud in a bottle
Be able to identify and describe different types of cloud and relate the children to rainfall.
Use a clean dry glass, clouds. There are three main types of clouds, cumulus, stratus and cirrus.
1.1 Cumulus are the separate woolly clouds with sharp outlines. They join to form a big cloud with a flat dark base and bulging upper part, like a cauliflower. It may rise high in the sky and then spread out to form an anvil cloud. This cloud has a dark base and makes lightning, thunder and heavy rain.
1.2 Stratus is a great misty mass of cloud. It has no sharp outline. Therefore, stratus clouds have no shape. Lots of cumulus clouds can join to make a stratus cloud.
1.3 When the wind blows over the sea then up over a mountain, a layer of stratus cloud can form over the mountain. This produces rain, mostly on the windward side of the mountain. This can be called the weather coast.
1.4 Cirrus clouds are very high clouds and look like wisps of cotton wool or hairs. They do not bring rain.
1. Hold a clean dry glass upside down under a running tap to make it cold. Breathe strongly into the glass. Show the thin layer of water drops inside the glass that come from their breath, Explain that water is in the air but you cannot see it.
2. Explain how air picks up water when it passes over the sea. You cannot see the water in the air. However, if the air rises it becomes small drops of water as you saw in the glass. You see white cloud where sunlight bounces off the small water drops. As the water drops grow larger they sink to the bottom of the cloud that then appears dark.
3. Draw the different shapes of cloud. Use the side of the chalk to show the shapeless stratus.
4. Take the children outside. What sort of cloud can they see? Is it raining? Can they see clouds near mountains? Draw the clouds and the land.
Extra Activity: Cloud watch. Record the clouds and rainfall every day for a week. Can they describe the clouds that bring rain? Most thunderstorms occur from December to March in the afternoon over the larger and more mountainous islands.
5.25 Push and pull forces
See diagram: 4.181
Be able to show that a push or pull is a force that can make an object start moving, stop moving or change direction.
Use a big box or pieces of wood with a string or rope attached, a pile of coins, a ruler, a pile of books, a catapult, glass of water, table cloth. This lesson should be based completely on the practical applications of force and movement. Use the suggested instructional materials (and more) to vary demonstrations for push and pull.
1. Explain that a force can move things. What are two ways of moving the big box? [Push the box, pull the box by string.] What is a force? [A push or a pull.] Tell a child to push the box and another child to pull the box. Pushing the box. In which way are the child's feet pushing? [Away from the box.] Pulling the box. In which way are the child's feet pushing? [towards the box.] Explain to the children that when there is a force in one direction there is also a force in the opposite direction. Child pulling the box. What happens if the string breaks? [Child's body moves away from the box and falls over.] What happens if the ground is slippery? [Feet move towards the box and child falls over.]
2. Make a pile of coins, a heap of books and put a glass of water on a cloth. Hit the bottom coin with a ruler. Does it move? [Yes.] Do the other coins move sideways? [No.] Why not? [The force from the ruler was only on the bottom coin.] Pile the books so that you can grip the bottom book. Pull the bottom book out quickly. Do other books move sideways? [No.] Why not? [The pulling force was only on the bottom book.] Put the glass of water on a table cloth. Can you take away the table cloth without touching the glass of water? [Pull the table cloth very quickly. BE CAREFUL! If something is not moving and there is no force on it how does it move? [It cannot move.]
3. Imagine you are paddling a canoe. Which way does the paddle move? [Backwards.] Where can you feel the force on the paddle? [On the back of the paddle.] Which way does the canoe move? [Forwards.] If you stop paddling does the canoe keep moving or does it stop? [It keeps moving.] Is there a force on the canoe? [No.] Hold the paddle upright in the water. What happens to the canoe? [it moves slower then stops.] Where can you feel the force on the paddle? [On the front of the paddle.] Explain that for every force in a direction, there is an equal force in the opposite direction.
4. Link two spring balances then pull them apart. Compare your reading. [They are the same.] Put a scale on the floor, put another scale upside down on it, compare the readings. [They are the same.] Sit in a still canoe or child's cart. Throw out a big stone. What happens? [The canoe or cart moves in the opposite direction to the stone.] Fire a gun. Which way does the bullet go What do you feel on your shoulder? [A force in the opposite direction to the bullet.] Hold a stone in a catapult. Pull back. Let go of the stone. Why does it move? [It is pushed forward by the rubber in the opposite direction to the pull back.] Explain that forces are always in pairs. For every force forward there is an equal force backwards. For every force down there is a force up.
Extra Activity: Use a spring balance, a heavy object that you can attach to the hook and a container of water. Hold up the spring balance. Read the weight. [No weight.] Attach the heavy object. What happened to the spring in the spring balance? [It was pulled down.] Read the weight of the object. Lower the heavy object into the water. What is the weight now? [Less than before.] Why is it less? [The water pushed up on the object. The spring in the spring balance was pushed up.] Stand in a river. Pick up the biggest stone you can from the bottom of the river. Now lift the stone above the water. What happens? [the stone feels much heavier.] Why? [The water is no longer pushing up on the stone.] What are the two kinds of force? [Push or pull.] Give an example of force which: 1. Starts something moving, 2. Makes something go faster, 3. Makes something go slower, 4. Stops something, 5. Changes the direction of movement of something. How does a squid swim it squirts water backwards and so it moves forwards?
5.26 Air pressure
See diagram: 4.272
Be able to show that air presses on us in all directions.
Use coins, water, jar, cardboard, bicycle pump and inner tube of bicycle tyre (optional) large tin can with screw on lid, burner. Demonstrations with the listed instructional materials by the teacher before the real class is essential.
1. Rub together two coins of the same size. You can separate them easily. Now wet the touching surfaces of the coins with water, and rub them together. Can you pull them apart easily? [No.] Press a dry coin on your forehead and on the underside of your arm. It falls off easily. do this again with a wet coin. What happens? [It sticks to you.] Why does this happen? [The water pushes out any air between the coins and your skin. Air is pressing in all directions on the coins.]
2. Fill a jar with water right to the top. Put a card on top of the jar so that there is no air inside and the top is completely covered. Put one hand firmly on the card and carefully turn the jar upside down with the other hand. Now take away the hand from the card. The water should stay inside the jar. What is pressing up on the card to stop the water from falling out? [Air.]
3. Fill a ball pen or plastic bag with air and tie the open end. Squeeze the bag or balloon. If you can feel the air pushing when you squeeze the balloon. [Yes.] When the air pushes this is called air pressure.
4. Put your finger over the hole at the end of a bicycle pump and press the handle in as far as you can. Let the handle go. It will be pushed back out. What pushed the handle out? [Air pressure.] Where you can find air. [All around us.]
Extra Activity:
1. Put some hot water in a coffee or milk tin. Put on the lid and heat the tin. What happens? [The lid flies off.] Why? [The hot water heats the air in the tin. The heated air expands and increases the air pressure inside the tin pushing the lid off.] During the observation, do not have your face too close to the tin.
2. Put some water in a large tin can which has straight sides and a screw on cap. Heat the can. When steam comes out screw on the lid and take away the burner. The can will collapse in all directions because of air pressure. What is all around us? [Air.] What does it do to us? [Air presses on us.] In which direction does air press? [All directions.]
3. Heat the can to boiling point, remove the flame and release cold water on it from a tap or bucket. The can similarly collapses.
4. Explain that cyclones occur when the air pressure is very low. This causes air to rush in towards the low pressure area causing strong winds.
5.27 Germinate bean seeds
See diagram 9.113.2d: Germinate bean seed
Be able to describe the stages in the germination of a bean seed.
Use bean seeds, wet paper, jar. The 2 types of germination:
1.1 Epigeal germination. The seed leaves (cotyledons) pop out of the ground, e.g. pea, bean.
2.2 Hypogeal germination. The seed remains in the ground, e.g. broad bean, corn, rice.
1. Soak some bean seeds in water. What changes do you see? [The skin becomes wrinkled and the seed swells.]
2. Put the soaked seeds in a jar with wet paper. tell the students to observe the seeds each day and describe what happens by completing this table: Bean, Day 1 Coat wrinkles, seed swells, Day 2 Root comes out, Day 3 Curved neck stage White finger stage, Day 4 Seed pops out of ground, Day 5 First leaves appear First leaves appear This can be extended to become a crop diary.
5.28 Depth of seeds
See diagram 9.113.2d: Seed levels
Be able to do an experiment to observe what happens when you plant seeds at different depths.
Use maize (corn) and bean seeds and a prepared seed bed. The best planting depth is usually two cm in wet soil and four cm in dry soil.
1. The aim of this experiment is to see what happens when seeds are planted at different depths.
2. Draw a diagram on the chalk board to show the design of the experiment. Also, tell the children to draw the observation table in their books.
3. Show how to plant the seeds and observe results.
4. Which depth is best for this seed Design of the Experiment 6 five four three two one Surface Observation Table Depth of Seed Number of days above ground Comment, Which depth is best Surface 1 finger deep 2 fingers deep 3 fingers deep 4 fingers deep 5 fingers deep more than one hand deep
Extra Activity: The two types of germination:
1. The seed coats come out of the ground (epigeal germination)
2. The seed coats remains under the ground (hypogeal germination)
3. Note the different types of seeds and the germination styles of each. Cut longitudinal and transverse sections of the corn grain. Be Careful - Soak it for a day in water before attempting to cut it! Observe the shapes seen and compare with the diagram.
5.29 Germinate maize grain
Be able to describe the germination of a maize grain.
Use maize grain, rice or sorghum, jar, wet paper, knife, magnifying glasses. The seed of corn, rice and sorghum is really a fruit with a hard tight wall. It is called a grain. In Australia and England corn is called maize. Use corn grain soaked in water for a few days, knife and magnifying glasses. About one week before the lesson plant some soaked corn grains. A shoot is the stem and the leaves. Learn to cut soaked grains longitudinally and transversely with a knife - Be Careful!
1. Show the dry corn grains and soaked corn grains. What is the difference? [Soaked corn grains are softer and fatter.]
2. Look at the germinating grain. Can you see the first root? The white shoot cap? The first leaves breaking through the shoot cap?
3. Cut a soaked corn grain in longitudinal half. Can you see its parts? When there is enough water, air and warmth, the new plant will start to grow. This is called germination. When all this stored food has been used up, the plant will make its own food in its leaves.
Extra Activity: Corn germination project. Plant some soaked corn grain. How many days before:
1. germination,
2. shoot cap shows,
3. first leaves break through shoot cap?
5.30 Roots absorb water
See diagram 9.195: Plants absorb water | See diagram 9.73.3: Root hairs
Be able to show that plants take in water.
Use small plants such as Amaranths, glass jars, ink, cooking oil, water. In this lesson you can show that plants take up water in two ways: see whether the ink gets into the plant. Put the plants in the inky
1. Give out plants and inky water. Can the plants take in water How can you show this? [You will put plants in inky water and water. Remove them out after a few hours.]
2. How you can see how much water plants take in? [You will put some oil on water, than it cannot evaporate.] Draw the diagram. How will you know that the water went into the plant and nowhere else? [The inky water will show us where the plant went. You can also set up a control that contains no plant.] Set up the demonstration and put it aside.
3. Give out small plants with well washed roots, and magnifying glasses. Can they see the tiny root hairs? Take the plant out of the inky water. Break open the stem. Can they see the ink inside? What can you learn from this? [Roots take in water.] Look at the water with the oil in top. Is the water level 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.]
1. Put some ink in water then put the plant roots in it. After a few hours break open the stem with their thumb nails and they will see the ink in the stem 2. Put the plant in water and add about one cm thick of cooking oil. Mark the level of the water. After about one day the level of the water drops. If you have another jar with oil floating on it, you will notice that the water level in this jar has not dropped. This is called a control. It shows that the water level dropped because the plant absorbed it. If you look at the roots of a small plant, you can see what it uses to take in water. It takes in water through the root hairs.
5.31 Leaves lose water
See diagram 9.194: Transpiration in plastic bag
Be able to show that plant leaves give out water.
Use plastic bags, string, small tree with soft green leaves. Plants take water from the soil into their roots through root hairs. From there, water moves up the stem through to the leaves.
1. You will do an experiment to see what happens when a plastic bag is tied over leaves.
2. Show a dry plastic bag, and a tree branch with dry green leaves. Tie the bag over the leaves and return to it later in the day. Show the bag over the leaves and ask them to tell you what they see inside. [Water.] Where did the water come from? [It comes from the leaves.] Draw the bag over the leaves. Explain that all plants lose water through their leaves.
Extra Activity: How can they prove that water comes from the leaves and not the stem? [Tie the plastic bag around the stem with the leaves pulled off. No water will form in the bag.] Draw a plant then draw arrows on it to show how water moves through it. Write labels on the arrows. [Soil water, root hairs, stem, leaves, air.] Sentence completion: Plants take water from the soil into their [roots] through their tiny [root hairs]. The water then goes up the [stem] into the [leaves] then into the [air].
5.32 Protect our mangroves
Be able to explain why you should keep mangroves growing.
Use pictures of specimens of mangroves or a natural mangrove environment close to the school. You should either prepare to visit mangroves or have some pictures of typical mangroves. It is preferable to have both, for a lasting impression.
Mangroves are big trees that can live in the shallow sea water near the shore. Their roots grow in the mud or sand and are under water at high tide. Some people want to cut down the mangroves to use the wood or to get rid of mosquitoes or to clean trees from the shore. Some people do not like mangrove swamps because they cannot walk through them easily. Why should you keep mangroves?
1. They are very interesting plants. Many years ago they lived in the forest but they learned to live in shallow sea water and they developed special parts to do this. Some mangroves have roots that grow up through the mud to get air. Some mangroves have tall stilt roots for holding onto rocky land. Some mangrove seeds grow into small plants while still attached to the tree, and others form a long root that spears into the mud when it falls. Can they see anything else that is special about mangroves?
2. Mangroves hold the mud together and can make new land. If you kill all the mangroves, the mud will be washed into the sea. Many animals live in the mud and are part of the food chain. Many small fish live among the mangroves where they can hide. When these fish grow bigger, they swim into the sea.
3. When mangrove leaves die they fall directly into the sea. These leaves act as a fertilizer.
4. Mangroves have been part of the scenery of the country for a long time. You should not destroy your natural environment but keep it for the next generation to enjoy and learn from.
Visit a mangrove swamp. How many different kinds of animals can they find living in the mangrove trees and in the mud? Dig a deep hole in the mud. Can they smell a gas produced by anaerobic bacteria living in the airless mud? [Hydrogen sulfide.] Can you recognize Red Mangrove (Rhizophora) which possesses silt roots for absorption from the muddy surface? Which of them possesses breathing roots to keep the plant well aerated? [White mangrove, Avicennia.] Taste the leaves of the two plants. Which of them tastes more salty? [Avicennia leaves because they have salt glands on the upper leaf. The lenticels are concentrated on the upper part of the breathing roots or pneumatophores.]
5.33 Collect rocks
Be able to make a collection of the different types of rocks near the school.
Use rock types from different locations, boxes for the rocks, a hammer and a magnifying glasses. Before the lesson collect different types or rocks from your area. Try to include rocks from cliff faces, streams, the sea shore. Also tell the children to bring rocks from home before you teach this lesson.
The three main types of rocks are:
1.1 Igneous rocks are formed from volcanoes. The rocks have cooled from very hot liquid rock. You can see whole crystals in them.
1.2 Sedimentary rocks are formed form particles of other rocks carried into rivers, lakes and the sea and then squeezed together. You can usually see the layers in the rock. Coral reef limestone are also classified as sedimentary rocks.
1.3 Metamorphic rocks were once igneous or sedimentary rocks but have been squeezed and heated again.
Do you know where the main rocks are found and their uses in your country?
1. Show the collection of rocks. Divide the rocks into those obtained from: 1.1 rivers, rounded pebbles, pieces from the edge of the river, 1.2 Sea shore, pieces of limestone, rounded stones, 1.3. Deep in the soil, stones, 1.4 Cliff faces, pieces of rock
2. Wash the stones. Divide the children into two groups:
2.1 Have crystals, they shine when you turn the rock. These are igneous rocks from volcanoes.
2.2 Do not have crystals, usually have layers. These are sedimentary rocks formed at the bottom of lakes and the sea.
3. Look at the igneous rocks. Are the crystals darker or lighter than the rest of the rock? How big are the crystals?
4. Look at the sedimentary rocks. Can you see the layers? Are all the particles the same size How big are they? Limestone may contain shells. If you put some acid on limestone, it forms bubbles of carbon dioxide gas.
5. Make a display of their rock collection. Label it: igneous, metamorphic, sedimentary, where found, description of crystals, colours, layers.
Extra Activity: You can try to name the rocks you find: basalt - heavy, dark rock, with very small crystals, some have green colour, andesite - light coloured, with very small crystals, limestone - looks dirty, no layers, fizzes in acid, mudstone - sedimentary with fine particles, layered, easily broken, sand stone - sedimentary, separate sand grains can be seen, conglomerate - sedimentary, has mixture of rounded stones and smaller particles.
5.34 Soil profiles
See diagram: 6.26
Be able to collect samples of different kinds of soils and what you see in them.
Use a sharp spade to dig the soil profiles and glass jars or pieces of glass. To dig a soil profile, find a flat area free of stones. Dig down vertically on three sides of a square. Dig the fourth side on a slope to make a wedge, then lift up the soil. The top few centimetres of soil are dark in colour because rotten plants and animals form a black sticky substance called humus. The topsoil is a layer containing the humus and most of the plant roots. Below it is the subsoil that contains mostly sand, stones and clay and some big tap roots. Below that is solid rock. The subsoil and topsoil may have formed from these rocks or the soil may have been dumped on the rocks by a river or water washing down. For his lesson see how many kinds of soil profiles you can collect:
1.1 Loam soil is a good garden soil found in river valleys. It may be black or red with much humus in the topsoil. Soil from a hill will have less topsoil than soil from a river valley.
1.2 Sandy soil is found just behind a beach or near the bend in a running river. It does not have much humus and dries out easily.
1.3 Clay soil is hard to dig in dry weather and very sticky in wet weather. It takes a long time to dry out and when it does it forms cracks. It usually has a red to brown colour.
1.4 Mangrove soils and poorly drained soils have a grey colour and often a funny smell.
1. Show how to dig a soil profile.
2. Collect different soil profiles. Measure the depth of topsoil and subsoil, note the colours and record where it was found.
3. Describe where different kinds of soil are found and why they are found there. What kinds of plants are growing on them Are soils good for gardens
Extra Activity: Dig soil profiles in a new garden, old garden, in a forest and on a steep slope. What differences do you see? Make a table and record your observations.
5.35 Fertilizer trial
Be able to set up a fertilizer trial to test whether fertilizer makes crops grow better.
You will need: Piece of land already dug, wooden pegs. Ask an agricultural officer for advice on which fertilizer to use for a trial. Use corn seeds or pineapple suckers or other planting material.
1. It is important to do experiments in agriculture. One kind of experiment is the fertilizer trial. The fertilizer trial is designed to try out different kinds of fertilizer in different amounts to see if fertilizer makes crops grow better.
2. Show how to mark out with wooden pegs the corners A. B. C. D and the mid points I, II, III, IV. The rows should all be the same size. The seeds or cuttings should be all planted the same distance apart in the rows.
3. Fertilizer is applied to the experiment plots A and D. No fertilizer is applied to plots B and C called control.
4. Draw the trial in an exercise book, write down the date.
5. Compare the crops in A and D with plots B and C plots. Does the fertilizer improve the crop yield?
Extra Activity: Set up a long-term fertilizer trial using tree crops. The plant nutrients are divided into:
1. Primary Plant Nutrients. They are nitrogen N, phosphorus P, and potassium K. (Potash is potassium oxide). One or more of these usually limits the yield of a crop, i.e. if there were more of this plant nutrient in the soil, the yield would be greater. These are the most important plant nutrients. They make from 2-6% of the dry weight of plants.
2. Secondary Plant Nutrients. They are sulfur S, iron Fe, calcium Ca and Magnesium Mg. These are needed in smaller amounts than the primary plant nutrients for normal growth. There is usually enough of these in the soil for good crop yields.
3. The micronutrients (sometimes called trace elements) are boron B, chlorine Cl, cobalt Co, copper Cu, manganese Mn, molybdenum Mo and zinc Zn. These are needed in very tiny amounts for the normal growth of some plants. If a soil does not have enough of a particular plant nutrient, e.g. nitrogen, you say that the soil is deficient in nitrogen. The only sure way to find out whether a soil is deficient in any plant nutrients is to ask a field officer of the Department of Agriculture to send some soil to a laboratory for chemical testing. However, you can tell if the soil is deficient in plant nutrients by examining your crop plants carefully. If a plant does not look healthy because there is not enough plant nutrient you say that it shows deficiency symptoms.
5.35.1 Deficiency symptoms:
1. Nitrogen N
The plants are small with few leaves that are pale green or yellow. The lower leaves look burnt and die early.
2. Phosphorus P
The plants are small and do not grow well. The leaves are a blue green colour and are usually purple underneath. The lower leaves die early. They take a long time to produce fruit that are small and badly shaped.
3. Potassium (potash) K
The plants have small main shoots but many side shoots. The leaves have dead white areas on the leaf edges and later die.
4. Sulfur S: The plants are small with pale green upper leaves.
5. Calcium Ca
The plants are small with unusually shaped leaves. The shoot tips may die.
6. Magnesium Mg
The leaves have green veins but are pale yellow between.
7. Iron Fe
The younger leaves look yellow. the lack of healthy green colour in the leaves is called chlorosis and this may be due to a deficiency in one or more plant nutrients.
5.36 Cover crops
See diagram 6.65.4: Centro, Siratro, Puero
Be able to name which plants are suitable for cover crops or green manure and explain how they improve the soil.
You will need: Actual specimens of common plants used for cover crops and green manure. Before the lesson obtain diagrams or specimens of the different plants used and find a place in a garden or plantation nearby where plants are growing. You should ask an agricultural officer to show you how to prepare these seeds or cuttings for planting. Some should be inoculated with a special Rhizobium mixture before planting.
1. Draw a diagram of a bed of soil on the chalk board. Hold your arm above it.
What would my arm protect the soil from? [Sunlight, rain.]
Why should you protect the soil from sunlight? [If the soil is too hot: 1.1 Humus is lost, 1.2 Some seeds cannot germinate, 1.3 Water is lost from the soil.]
Why should you protect soil from rain? [Heavy raindrops make the soil splash up then get washed away.]
2. What can you use to protect the soil? Can you use sheets of iron? [No.] Can you use trees? [Yes, but when the trees grow big they will use most of the light and water so you can't grow other crops.] You use plants that do not grow high but cover all the ground with lots of leaves. You use legumes called Puero, Centro and Calopogonium. They are called legumes.
3. Legumes will: 3.1. Lower soil temperature and evaporation of water, 3.2 Protect soil from splash erosion but let water trickle down into the soil
3.3. Shade the weeds so they cannot grow, 3.4 Add humus and nitrogen fertilizer to the soil when the leaves die.
Can plants cause problems? [Yes, they can grow all over young coconuts, so clear a circle around each palm.]
4. If you are not using land for some time, such as during the school holidays, you can protect the soil and keep weeds out by planting legumes. However, clearing plants is hard work. If you plant an upright legume such as cow pea or mung bean, you can easily dig them into the soil. This is called green manuring. About 3-6 weeks after digging, the plants rot in the soil and the plant foods will be available for their next crop.
5. Show the legume plants and let the children feel the soil under a cover crop.
Extra Activity: Sowing a of green manure. Note that Centro has hard seeds that take a long time to germinate unless you treat them with boiling water. Puero and Calopogonium grow well in shade under leaves. You cannot dig in green manure crops under tree crops because it would damage the roots. Other good legumes are Hetero and Siratro that produce good grains for cattle and Stylo that is good at smothering weeds.
5.37 Rain on slopes 1
See diagram: 24.4.5
Be able to describe what happens when water falls on different slopes.
You will need: 1.1 One to four jam tins with holes punched in the bottom, 1.2 a soil ridge that is flat on top, has one side sloping steeply and the other side sloping gradually, 1.3. spades. Teach this lesson outside in the garden.
1. Show to how to make two ridges that are flat on top. One ridge has steep sides and the other has gradual sloping sides. There should be no plants or stones on the ridge, only fine soil.
2. Give each group a tin with holes in the bottom. Show how to fill the tin with water and make artificial rain.
3. Make rain on the gradual slope. Tell the children what happens. [Some water just soaks into the soil, some water runs down the slope and carries some soil down making a gully.]
4. Make rain on the steep slope. Explain what happens. [Much soil is carried down the slope to make a big gully.]
5 . Where should you make gardens? [On flat ground or else the soil will be washed away.]
Extra Activity: Do the same but cover the soil with grass. Grass stops the soil from being carried away.
5.37.1 Rain on slopes 2
Be able 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? [Nothing, it is not washed away.]
3. Shake the rain on sloping soil containing grass, leaves and sticks. What happens to the soil? [Some of it is washed down.]
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 soil on slopes and shake the rain on them. 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.
Extra Activity: How village people try to stop erosion in their gardens.
5.38 Mulch garden soil
See also 6.9.14: Composting
Be able to mulch garden soil
Use a sloping garden bed. Cover half with mulch and leave the other half not covered. After about one month you should see the following differences: Feel the bare soil and the soil under the mulch. What differences do you see and feel? Are there any weeds under the mulch? Mulching is a thick layer of leaves, dry grass, or husks over the soil. It controls weeds by shading the students from sunlight. It absorbs and stores rainfall and lessens evaporation from the soil. Mulching protects the soil from the splash erosion of heavy rain drops. Mulching should not touch the stems of plants if the mulch may contain pests and diseases. Mulching must be replaced as it rots into the soil. Dry grass mulch or dry compost which is not rotten may take nitrogen plant nutrient out of the soil.
Mulched Soil Not Mulched Soil
cooler soil warmer soil
damper soil dryer soil
less soil erosion more soil erosion
darker coloured topsoil (more organic matter) lighter coloured topsoil (less organic matter)
fewer weeds (but mulch itself may contain weed seeds) more weeds
1. Mulch is chopped grass, weeds, leaves and other plants which acts as a blanket layer over garden soil. Mulch is not mixed into the soil but as it rots it enters the soil. As the mulch slowly rots into the soil new plant material should be added on top of the mulch. The garden should always be completely covered with 5 cm of mulch leaving no bare patches on the soil. The mulch should not touch the stems of crop plants because some pests and diseases may be in the mulch which could attack the plants. You can also use black plastic. The cover of dead plants is called mulch.
2. The advantages of mulching garden beds are as follows: 2.1. It controls weeds because the mulch stops light getting to their leaves. 2.2. It stops rainfall from washing away the soil. 2.3. It stores water which the plant can use in the dry season. 2.4. It stops loss of water from the soil into the air because the mulch is like a blanket over the garden bed. 2.5. The mulch rots slowly into the soil to improve the soil structure.
3. Disadvantages of mulching garden beds are as follows: 3.1 It requires more work to collect, cut and put plant material on the soil. 3.2 The work is often not done properly leaving bare patches. 3.3 When the bottom layer of the mulch rots it may take some nitrogen plant nutrient from the soil. 3.4 Insect pests and disease may live in infected plants used for mulch.
4. Before mulching school gardens always ask an agricultural officer whether it is safe to use mulch with crop plants.
5.39 Make clay pots
Be able to make a pot from sand and clay.
Use fresh sand and different types of clay, banana fibre, round stones, fuel wood. About a week before the lesson, collect the same amount of red clay and washed sand. Mix them in equal parts by pounding with a wide stick. Wrap it in banana leaves to keep it moist.
1. Explain that this method of making pots is very old and is still is in some parts of the world.
2. Give each group a lump of damp clay. Divide it into four smaller pieces. Flatten each lump with a round stone.
3. Twist the banana fibre to make a hoop for a stand.
4. Mould one piece over a stone to make the bowl shape. Put this on the hoop. Add flat pieces to build up the walls, keeping the stone inside. Cut the lip smooth with a coconut fibre and smooth the edge with wet fingers, take the stone out. Write your name in the side with a small stick.
5. Leave the pot to dry for 1-4 weeks.
Extra Activity: Firing the pot. Get lots of little softwood sticks. Put the pot on top of some, then build a house of sticks all around the pot. Set fire to the house of sticks. Encourage the children to visit different locations where pots are made from clay.
5.40 Make potash from ash
Be able to obtain potash from wood ash.
Use lots of white wood ash from burning large pieces of wood until only the soft ash is left. Glass jars or bottles. Filter paper or any soft paper or cotton wool. Filter funnel empty coconut shell with a small hole in it, burners and burner stands or a small fire.
1. What you got when you burnt wood. [Carbon.] How you do you make ash? [By burning wood in a very hot fire.]
2. Put the ash in a beaker or jar so that it is half full. Put some water in and stir up the ash and water very well. Filter the liquid from the jar into another jar or bottle. Put some filtered liquid on a tin lid. Heat the liquid so that it evaporates. What is left? [Some white substance.]
3. What does the white substance taste like? [Salty.] Where does the white substance come from? [The wood ash.] The wood ash contains something like salt called potash. Potash is a very good fertilizer for the gardens.
4. What kind of substance you found in the wood lesson. [Carbon.] Where does the wood get the salty substance from? [From the soil.]
5. If the people near their school get salt from ash.
Extra Activity: How you can test whether potash is a good fertilizer or not. [Fertilizer trial.]
Sentence Completion: Wood burns to form [carbon] and [potash]. Trees get [potash] from the soil.
5.41 Keep water clean
Be able to explain how to keep water clean for humans, animals and plants.
Use sample of pure drinking and polluted water, examples of purifying processes. Before the lesson visit a local source of drinking water or a river and the seashore. Note where the water is clean. Use samples of good drinking water and smelly polluted water that is unfit for drinking. Bring some rubbish found in a river or on the seashore.
1. Show the good samples of good drinking water and water unfit for drinking. Tell them to look at the samples, smell them and tell you the difference. Why do you need clean water? [Dirty water can make us sick.] Explain that dirty water can contain bacteria that make us sick. Bacteria are so small that you cannot see them with your naked eyes. You need a microscope to see them.
2. How can you be sure that water is clean and will not make us sick?
2.1. Boil water for babies.
2.2. Drink rainwater.
2.3. Drink clean water from wells or rivers.
2.4. Drink clean water from treated sources.
3. How you can you make clean water dirty:
3.1 Throwing rubbish or dead animals in the river.
3.2 People putting their faeces or urine in the river. Toilets must be 20 metres from the river otherwise bacteria from sick people can get into the water.
3.3 Chemicals such as insecticides and weedicides can wash into the river from sprayed crops. Soil can wash into the river to make it muddy.
4. How you can keep rivers clean:
4.1 Bury all rubbish.
4.2 Build toilets at least 20 m from the river and at least one metre deep.
4.3 Do not let agricultural chemicals wash into rivers. Bury unused chemicals.
4.4 Use contour banks to stop soil washing into rivers.
4.5 Do plants and animals in the rivers and sea need clean water? [Yes.] How can dirty water hurt them? Disease and chemicals can kill them. Muddy water and rubbish stop them getting light. Muddy water can kill coral. Plastic rubbish can kill some fish if they eat it.
Extra Activity:
1. Visit a pig latrine. Is it 20 metres from a river, houses, pig yards, wells? Is it more than one metre deep? Does it have a cover? Are there any flies around it?
2. Visit a river. Is there any rubbish in it? Is muddy water caused by garden soil washing into it? Can chemicals get into it?
3. Visit the seashore. Is the water muddy? Can animals and plants live in the muddy water? Collect the flotsam washed up on the beach. How did it get there? Does it contain plastics? Plastics do not rot quickly and remain rubbish for a long time.
5.42 Heated air expands
See diagram 20.1.1: Heated air expands
Be able to describe what happens when a bottle is heated and then cooled. Can explain that air expands when heated and contracts when cooled?
Use a bottle, plastic tube from ball pen, burner, glass jar. Be careful! This experiment is dangerous if you heat the bottle too much. First do the demonstration in a preparation room before doing it in front of children. Strict adherence to instructions is very essential here if accidents are to be avoided.
Method: Demonstration preferred
1. Give out the materials and tell the children to push the ball pen tube into the hole in the cork, push the cork into the mouth of the bottle so that no air can leak out around the side of the cork, hold the neck of the bottle with a piece of rag or paper and tip the bottle so that the end of the tube is about three cm under the level of the water in the tin. eat the bottle gently with the burner for a few minutes and watch what happens. [Bubbles come out of the tube in the water.]
2. Stop heating the bottle. Put out the burner flame. Keep the end of the tube under the water and watch what happens as the bottle cools down. [Water is sucked into the tube.]
Extra Activity: Explain why it is dangerous to heat closed bottles or gas cylinders because when gases are heated you expand. If expansion occurs very quickly this is called an explosion.
Sentence Completion: When the air is heated it [expands]. When air is cooled it [contracts].
5.43 Burn to make carbon
Be able to show that all living things contain carbon.
Use a candle or burner, old torch battery from a radio, paper, pencil, dry leaves, insects, sugar, food, tin lids, iron nails, tongs or a holder to hold nails in the fire. In this lesson you will burn a variety of materials that are alive or were once alive and in each case you will show that when the burning is completed only carbon is left. Carbon is an element represented by the symbol C. Oxygen is represented with O. If carbon is heated to a very high temperature, it can form the gas carbon dioxide or CO. So if you heat the substances in this experiment to high temperatures you would not have any carbon left, it would all have turned into carbon dioxide gas. Break open the battery and take out the black rod in the middle. Dig a hole outside where there is good topsoil containing plenty of black humus.
1. Give out the candle or burner, tongs and things to be burned. Hold a tin lid in the candle flame. Cool the lid then wipe off the black stuff called soot. Explain that this black stuff is called carbon. Put some carbon on your fingers.
2. Make a pencil mark on paper then rub your finger on it. The black mark on your finger is carbon.
3. Show the black rod in the centre of the battery. It is carbon.
4. Burn paper, an insect, piece of meat or sweet potato. What happens to them? [They become black.] What is the black stuff? [Carbon.]
5. Heat up some sugar on a tin lid. What happens to the sugar? [It burns to form carbon.]
6. Take the children outside to the hole. How is the topsoil different from the subsoil? [It is darker.] What is in the topsoil? [Rotten plants and animals.] Why is it black? [The rotten plants and animals become carbon.] Explain that the substance from rotten plants and animals that contain carbon is called humus.
Extra Activity:
1. Take a piece of burnt wood, it is called charcoal. Heat it until it glows red. Why does it get smaller? [The carbon is changed into carbon dioxide gas.] Relate this to what happens in a charcoal pressing iron and when used for cooking locally.
2. Burn some feathers or hair. Carbon is formed but there is also a strong small. The smell comes from another substance called sulfur S, which burns to form the gas sulfur dioxide, SO2.