School Science Lessons
Primary Science Lessons Year 4
2012-07-04 SP
Please send comments to: J.Elfick@uq.edu.au
Suggested answers to the teacher's questions are shown within [square brackets].
Table of contents
4.1 Animal legs
4.2 Animal friends
4.3 Fish parts
4.4 Frog life cycle
4.5.0 Lizards and snakes
4.5.1 Snake bite
4.6 Care of dogs
4.7 How sound travels
4.8 Flying kites
4.9 Heat from rubbing
4.10 Heat different solids
4.11 Air temperature
4.12 Smoke moves up and down
4.13 Inertia tricks
4.14 Prepare crystals
4.15 Pace distances
4.16 Air resistance
4.17 Shapes game
4.18 Diameter of a thread
4.19 Prepare invisible inks
4.20 Measure chest expansion
4.22 Memory games
4.23 Test your reflexes
4.24 Speed of reaction
4.25 Uses of peas and beans, Acacia, Leucaena
4.26 Legumes
4.27 Collect bean plants
4.28 Bean life cycle
4.29 Bean flower
4.30 Bean seeds and pods
4.31 How seedlings grow
4.32 Weathering rocks
4.33 Make sedimentary rocks
4.34 Protect soils
4.35 Natural fertilizers
4.36 Water climbs up soil
4.37 Soil water bottle
4.38 Liquids in the sun
4.39 Melt different solids
4.40 Heat and cool water
4.41 Ice experiments
4.42 Sundials
4.43 Water from the air
4.1 Animal legs
See diagram 9.300: Animals
Be able to recognize different animals by the way the animals move.
Use pictures of different animals for looking at their legs:
1. Cats, dogs, horses and elephants (mammals) have four legs for walking.
2. Centipedes, millipedes have many legs for walking.
3. Chickens, ducks, seagulls (birds) have wings for flying and two feet for walking or perching.
4. Fish, and sharks have fins for swimming.
5. Frogs, salamanders (amphibians) have four webbed feet for swimming and jumping, tadpoles have tails for swimming.
6. Insects have six legs for walking. Some have wings for flying, e.g. cockroach, caterpillar and butterfly, beetles, flies, bugs, aphids, grasshopper.
7. Lizards, crocodiles, dinosaurs (reptiles) have four legs for walking. Snakes have no feet but can move by wriggling.
8. Sea Squirts and corals cannot move but can open and close.
9. Shrimps, prawns, crabs, crayfish, lobsters (crustaceans) have many legs for swimming and walking.
10. Snails, mussels, shellfish (mollusc) have one foot for sliding movement.
11. Spiders have eight legs for walking.
12. Starfish, sea urchins (echinoderms) have spine-like legs and tiny legs like tubes.
13. Worms have no legs but can move by wriggling, e.g. earthworms, round worm parasites in animals.
1. Show the pictures of animals. Let the children look at the legs very carefully. Can you see the different kinds of legs?
2. Different animals game: All the children sit in a circle. The teacher walks around the circle, points to a picture of an animal and points to a child. The child has to call out the name of the animal. If the child is correct, the child stays in the circle. If wrong, the child has to leave the circle.
Extra Activity
Funny Animals Game.
1. See the funny cat. It can eat lots of different kinds of animals. Can you write in the squares the names of the animals it has eaten? It can eat: ant, bird, chicken, duck, fish, frog, lizard, pig, turtle? [1. fish.] [2. bird.] [3. lizard.] [4. ant.]
2. See the funny fish. It can eat different animals if they are in the water or if they are get too close to the water. Can you write in the squares the names of the animals it has eaten: ant, chicken, duck, fish, frog? [1. (across) frog.] [1. (down) fish.] [2. chicken.] [3. duck.] [4. ant.]
4.2 Animal friends
Be able to recognize the animals that are your friends and the animals that are your enemies.
Animal enemies are those that harm us, e.g. mosquitos, or harm your livestock or crops, e.g. roundworms or cutworms. Animal friends eat harmful animals, e.g. frogs eat insects, and millipedes help dead plants to rot. Some animal enemies: caterpillars, grasshoppers, aphids that carry disease, pigs that dig up gardens, rats carry disease. Some animals can be friends or enemies, e.g. birds, snakes, crocodiles. Use some jars for collecting.
1. Explain that animals can be friends or enemies. How can insects be enemies? [They can bite us, eat food plants, cutworms, carry disease, aphids.] Which large animals are enemies? [Rat, sharks, wild pigs in the garden. Which insects are your friends? [Mantis, wasps, bees.] Which other animals are your friends? [Earthworms, frogs, toads, snakes.]
2. Garden Walk: Look for animals that are friends and enemies. Collect some in jars and take them back to the classroom.
3. Animals can be your friends or enemies. Caterpillars, grasshoppers and rats can eat your food plants. Frogs, birds and snakes can eat them. your animal enemies are eaten by your animal friends.
4.3 Fish parts
See diagram 9.301: Parts of a fish | See diagram 9.302: Shark, bony fish
Be able to 1. examine live fish, 2. draw the fish and label the parts, 3. observe the movement of the mouth and fins.
Provide some fish or tell the children to bring some, one jar per group.
1. Can the children see these parts: head, body, tail, fins, mouth, anus, eye, gill, cover, scales? Draw your fish and label the parts.
2. Catch one fish and show the children the gills inside the gill cover. Watch the mouth and gill cover. Do they open and close? [Water goes into the mouth, over the gills, and out past the gill cover, that is how the fish breathes.] Briefly explain the process of gaseous exchange in the fish.
3. Watch the different fins very closely, how do they help the fish to move? [The fins help it to change direction, to keep upright, to stay in the same place, to move forward in the water.]
Extra Activity
Continuous activity, let the children try to keep the fish for some days. Start a classroom aquarium.
4.4 Frog life cycle
See diagram 9.310: Frog life cycle
Be able to explain the different stages in the life cycle of a frog.
Look for frogs eggs and tadpoles then bring them to school. Some frogs have appeared on postage stamps: Giant Toad, Marsh Frog, Horned Frog, Tree Frog, Guppy's Frog
1. Show pictures of frogs. Ask them: How are frogs different from lizards and snakes? [Frogs have no scales, have a soft skin and lay their eggs in the water.]
2. Explain the life cycle: A male frog mates with a female frog by sitting on her back. When the female frog lays eggs, the male frog puts sperm on them, in the water. Most of the eggs are fertilized because the sperm and eggs are laid very close to each other. The eggs are covered in a clear jelly. The fertilized eggs grow into tadpoles. The tadpoles have tails that help them to swim. After several weeks the tadpoles are eaten by fish so although a female frog lays hundreds of eggs only a few will grow into adult frogs. Draw the frog's life cycle.
[SAFETY
Toads have a venom gland on each shoulder that secretes a white fluid. Other venom glands may distributed over the back. Contact with a child's eyes, mouth, nostrils causes severe pain and irritation. Treat by washing fluid from the body. If venom is in the eyes, irrigate with water for 20 minutes. If venom is ingested, induce vomiting and seek medical aid. Wash your hands thoroughly after giving treatment. Frogs may exude a toxic chemical from the skin. Treat touching frogs as for touching toads. Some fairy stories tell of girls kissing frogs or toads which then turn into a prince by magic. Do not let children imitate such a practice!]
4.5.0 Lizards and snakes
See 4.5.1 Snake bite
Be able to recognize different kinds of lizards and snakes. Do not ask children to bring lizards and snakes to school!
1. There are three main types of reptiles: 1. turtle and tortoise, 2. crocodile, 3. lizard and snake.
2. Reptiles have a scaly skin, lay shelled eggs on the land and do not have gills when young.
3. Reptiles are similar to amphibians, e.g. frogs. Amphibians have a soft skin with no scales, lay soft eggs in the water and the tadpoles breathe with gills.
4. Some lizards and snakes appear on postage stamps, e.g. Skink, Sea Snake, Lizard, Tree Snake, Monitor Lizard, Whip Snake, Boa, Gecko, Skink.
5. There are four kinds of lizards: 5.1 Dragons, e.g. Angle Head They are found mainly in Usable, San Cristobal and Eastern Islands. They live in trees, eat insects and fruit, moves at night. 5.2 Gecko, e.g. Tree Gecko, scaly toed lizards, small lizards that can climb up vertical walls, can make a noise, can drop off their tails have no eyelids, eat insects, live on ground or in trees, move at night. Found on most islands. 5.3 Skink, e.g. EMI, large skink. They have strong legs for running, are bigger then the gecko, can drop their tails, often found in strangler figs, can bite you if you tease them. 5.4 Goons or monitor lizards, e.g. Varian's. Live on small islands. It has a black body with yellow spots. It is the largest lizard. It lives near mangroves where it eats crabs, small animals and turtle eggs.
6. The six main types of snakes in the Solomon Islands are as follows:
6.1 Sea Snake
Common in shallow seas especially near Renal Islands, but lays eggs on shore. Blue grey colour with black bands, up to one metre long, eats fish and lizards, is poisonous but does not often attack people.
6.2. Red Banded Tree Snake
Not common, brown with darker bands, grows to two metres, moves in trees at night but may be found in roofs of houses, it is poisonous and will try to bite you, eats lizards, chickens and eggs.
6.3 Whip Snake
It is common in forest and agricultural areas, is green brown and grey underneath, has a thin body, and grows to one metre, not poisonous, eats frogs.
6.4 Boa
Common on most islands, light brown with zigzag patterns, grows to one metre, usually moves only at night, lives on the ground or sometimes in trees, kills lizards, rats and birds by squeezing them, not venomous but it will strike at you.
6.5 Burrowing Snake
A small common snake, travels at night, burrows underground, smooth scales, tail has a spine, has no neck and weak eyes, lives on insects, not poisonous, hard to find.
6.6 Common Brown Snake (Guppy's Snake.)
Common snake, about 75 cm long, redrawn with bands, white underneath, eats frogs and lizards during the day in the forest, may be poisonous, a loud hissing sound if you chase it.
1. Show pictures of lizards and snakes. How are they the same? [All have scales and lay eggs on the sand.] What other animals have scales and lay eggs on the land? [Turtles and crocodiles.]
2. Ask children to describe lizards and snakes they have seen. Have you seen any of the animals in the diagrams? What are the local names for them?
3. Draw a lizard and a snake.
4. Select some lizards and snakes and describe them and what they do and eat.
Extra Activity
Watching live lizards and snakes. Look at them from above. How do they move along the ground?
4.5.1 Snake bite
If you are bitten by a snake, tie a bandage about the wound and get somebody to take you to hospital without delay. Note the following rules:
1. Keep still, otherwise the snake venom will spread quicker through your body.
2. Apply a tight pressure bandage to the area bitten, with the same tension as a bandage for a sprain.
3. Telephone triple 0, or the local hospital or doctor.
4. Keep still and wait for help. Do not go anywhere to get help.
5. Do not try to kill the snake for identification
6. Do not wash the wound caused by the snake bite because doctors may want to analyse the snake poison before giving you the antivenom (antivenin, antivenene).
7. Do not use a tourniquet because it can cause more damage.
8. Do not cut or suck the wound made by the snake bite because this may introduce venom into the bloodstream.
9. Do not drink, eat or take any medicine, even if you are in pain.
4.6 Care of dogs
See diagram 9.308: Care of dogs
Be able to care for a pet dog. Use a pet dog or puppy in the classroom.
1. Show the class the pet dog, Show the parts of the dog. Lift up a front paw then roll over the dog. What do you see?
2. Dogs should be fed meat and other foods once a day, have clean water and have a dry sleeping place under a house.
3. Press your hand against the chest behind the foreleg. Can you feel its heart beat? Show how to pat the dog but do not touch it under the tail because you might get disease. Feel the dog's coat. Is it free of fleas? You can give the dog a bath using plenty of soap and some insecticide to kill fleas.
4. Dogs must be trained to do what humans want them to do. When a puppy does something bad, you can shake it and say "no". For big dogs push the nose to the ground or spank them under the hip with your hand, not a stick.
Extra Activity
Can you Show how to train a dog to respond to simple commands such as "sit" and "come"?
4.7 How sound travels
See diagram 26.192: Bell from a spoon | See diagram 26.194: Stretched rubber band | See diagram 26.195: String telephone
Be able to show that sound can pass through solids, liquids and gases.
Use a bucket of water, tin plate. Different organs of the body can sense sounds. your ears, muscles and eyes can easily detect sounds. Sound can pass through the three states of matter: solids, liquids and gases.
1. Say something to the class. Tell some children to repeat what you said. What have you heard? [Talking, noise, sound.] What part of your body hears the sound? [Ears.] What is all around us even if you cannot see it? [Air.] How does the sound reach your ears? [It travels through the air.]
2. Press one ear to the surface of the desk and block the other ear with a finger. Use the other hand to make slight tapping and scratching sounds on the other end of the desk. What happens? [The sound can be heard very clearly.] How does the sound reach your ears? [It travels through the desk.] Through what type of material does the sound travel? [Solid.]
3. Drop a tin plate into a bucket of water. Block one ear and dip the other ear into the water. Tap the tin plate with a knife. Can you hear it? [Yes.] Can sound travel through liquid? [Yes.] What can sound travel through? [Solid, liquid, gas.]
4. If the same tapping noise is made is it easier to hear if the sound presses through solid, liquid or gas? [Solid, then liquid, then gas.]
Extra Activity
Let children place their ears very close to the bare ground and let a colleague or more than two children march on the other end of the floor. What do you feel? How does this activity compare with 2 above? The teacher should explain how the Red Indians used this method to detect enemy movement. How useful is this old method in modern warfare?
4.8 Flying kites
Be able to make a kite and fly it. You will need: Sticks one m long and one cm wide, a long fishing line (or a good substitute) string, old wide newspaper or light cloth and glue. The three kite rules: 1. Do not use wire or metal in the kite. 2. Do not fly when the string is wet or if there is a thunderstorm. 3. Do not fly near electrical wires. To make a two stick kite, cut a notch in the end of each stick, then bind each end with string. Bring together the cross sticks at A. Wind a strong piece of string around the notches, DEBC. Lay the cross sticks on paper or cloth and cut out the shape about 1 cm bigger. Turn the edges over the string and glue or sew. Make a tail out of string and pieces of rag and attach the tail at D. Attach a loose string from E to C. Then attach the fishing line to the middle of the loose string. To make a tail-less bow kite, tie a strong string to EC after binding together the cross sticks and pull it until EC is bent into a bow so that the distance from A to the bow string is 20 cm. Then attach a loose end of string to D and the other end to AB about 8 cm from B. Attach the fishing line to the loose string. Use a windy day. Avoid doing this during a thunderstorm.
1. Take the children outside. Point in the direction of the wind, i.e. turn their back to the wind. Point in the same direction it is blowing. Show them the wet finger test, suck their finger, hold it to the wind. The side of the finger feeling cool is the direction from which the wind comes. Remember that a south wind is blowing from the south.
2. Hold up the kite and run into the wind until it takes off. Hold it at a steady height.
3. Describe what happens when you: 1. Pull the string in quickly? [Kite moves steadily, starts to move up.] Let the string out quickly? [Kite loops about, starts to move downwards.] How do you pull or let out the string to make the kite fly higher or lower? [Higher, pull in quickly, lower, let out string quickly.] 4. If you have a tailed kite, you can make the tail longer or shorter. How does the kite fly when the tail is shorter Flatter or longer? [More upright.] If you have a tail less bow kite, you can move the attachment of the fishing line closer to the head of the kite or closer to the tail of the kite. How does the kite fly if you move the knot up? [More upright.] How does the kite fly if you move the knot down? [Flatter.] Show you with their arms the angle at which the kite is flying. Let the kite rise and fall. Move their arms so that the angle between the string and the ground can be measured. 5. Make a quick one and try them.
Extra Activity
Make and fly their own type of kite. Sentence completion: When you pull the string in quickly, the angle [increases]. When you let the string out quickly the angle [decreases].
Commercial
Kite collection: Single line designs, Dual line stunt kites, Dual line parafoil kites
4.9 Heat from rubbing
Be able to explain the importance of heat produced by rubbing things together.
Use palms of the hands, smooth glassy surfaces, sand paper or a rough stone, surfaces, grease, 2B pencils, a bicycle or car. This lesson is about friction and the prevention of friction by lubrication. Remember that friction can help and harm us. It can harm us if you touch a spinning wheel or if an engine wears out but can help us when brakes slow down a car or bicycle. There is friction between your feet and the ground. You would fall over otherwise.
1. Rub the palms of the hands together slowly and then quickly. What do you notice? [Our hands get hot and even hotter when you rub them together quickly.]
2. Put two identical coins on a rug or on a table cloth. Put your index finger on one of the coins and rub it forwards and backwards. Put you fingers on both coins. The coin that you rubbed feels hotter.
3. Draw a rectangle, colour it in with a 2B pencil (ABCD) and to mark off the same area on blank paper (CD). Rub the line from C to D often. Can you rub it hard twenty times? [No, it is too hot.] Rub your fingers from A to B in the same way. Is it possible to rub it more than twenty times? [Yes, the finger does not get too hot.] Give the children some sand paper or a rough stone and some oil or grease. Tell them to rub their finger over the rough surface. What do you feel? [It gets hot.] Does it get hotter than when rubbing one's finger on the paper? [Yes.] What is the difference? [The paper is smoother. The sandpaper or stone is rougher.] Put some grease or oil on the rough surface and rub again. What do you feel? [The finger does not get hot.] What did the oil or grease do? [It made the rough surfaces smooth again.] Feel a turning wheel and axle. What do you feel? [The axle gets hot.] How can you stop it from getting too hot? [Put oil or grease on the axle.] Put on the brakes of a bicycle. Feel the brake shoes. How do they feel? [Hot because they are being rubbed away.]
Extra Activity
Think of examples of rubbing things causing heat, e.g. tires on the road, making a fire with a bow. Sentence completion: When things are rubbed [together] they get [hot]. [Rubbing] Things that feel [rough] gets hotter than [rubbing] things that feel smooth. You put [oil] in an engine to stop the parts rubbing together. If the engine gets too [hot] you know that it needs more oil.
4.10 Heat different solids
See diagram 23.1.2: Heat different solids
Be able to show that heat moves faster through some solids called conductors and slower through other solids called insulators.
Use long nails or wire or tin lids, green wet sticks and cloth, candles or a small fire. In this lesson be sure that the children will not burn their fingers. Most metals are conductors. Most non-metals are insulators. Discussions on conductors or insulators should centre more on applications in day-to-day activities in the school and in the home.
1. Give out the equipment and light the candle. Pick up the nail or wire. How does it feel? [Cold.] Hold the nail in the left hand. Hold the other end in a flame. Touch the middle of the nail with a finger of the right hand. What do you feel? [The nail is getting hotter.] Which finger feels hotter first? [The finger of the right hand.] Why? [Heat is moving along the nail from the flame.] The nail, which lets heat move along it quickly, is a conductor of heat.
2. Hold a green wet stick in the flame as before. How did it feel when picked up? [It feels not as cold as the nail.] How did it feel after having been in the flame? [It feels not as hot as the nail.] Heat moves along the stick slowly. It is not a conductor of heat but an insulator.
3. Wrap one end of a nail in cloth. Hold this end and put the other end in the flame. Does the nail get hot? [Yes.] Do your fingers get hot? [No.] Why? [The cloth does not let the heat pass through it quickly.] The cloth is also an insulator of heat.
4. A frying pan is made of iron but has a wooden handle. Why is it made of these two solids? [The iron parts conduct heat to cook the food. The wooden handle does not conduct heat. It is an insulator and that is why you can hold it.]
Extra Activity
List conductors (metals) and insulators (non-metals) in the classroom. Good conductors (most metals), e.g. iron, aluminium, copper, silver. Bad conductors (most non-metals), e.g. air, cork, water, plastic, paper, glass, stone. Sentence completion: Solids that let heat move through them quickly are called [conductors], e.g. [metals, iron, copper, aluminium]. Solids that do not let heat move through them quickly are called bad [conductors] or [insulators], e.g. [cloth, wood, stone, plastic].
4.11 Air temperature
See diagram 23.7.03: Wall thermometer
1. Be able to observe the difference in temperature in different places.
You will need a 0oC to 100oC thermometer and different places where differences in temperature can be seen. Do not let children hold the bulb of the temperature in the sun. The thermometer will keep absorbing heat energy, the mercury will continue to expand and will break the thermometer. Measure temperature differences at different places in the classroom, different depths in the soil, bare soil, soil under mulch, soil under shade, under different types of shade grass, coconut, banana, bush, in and out of water or mud, in a compost heap.
1. Each child must read the thermometer. Explain how to measure the temperature in different places. Write a list of places in their book.
2. Give each child a chance to read the thermometer in a different place and record in their book.
3. What differences did they notice, e.g. under different shades, in the soil, in the classroom, in water?
Extra Activity: How does temperature in soil change during the day? Does it change more, when deep in the soil or just under the surface?
2. Be able to measure and record change of temperature during the day.
This lesson is designed to give more practice in reading a thermometer, practice in making regular observations, and recording them. If recordings can be made for more then one day, they will show the recurring pattern of temperature change each day. Use a 0 to 100oC thermometer fixed in the classroom in a place out of the sun but where the wind can blow by it. Put a recording sheet next to it marked: date, time and temperature. Put a graph sheet on the wall to record a set of temperature readings from the previous day.
then individual readings.
1. Draw part of the temperature scale of the thermometer on the chalk board. Give the children practice at reading the scale.
2. Show the place for the thermometer and recording sheet. Explain how they will read the temperature every half hour during the day and record it on the recording sheet and graph sheet. Let them all read the temperature now, then give pairs of students the job of reading temperature at different times.
3. Show their temperature readings from the previous day. Write the recording sheet on the chalkboard. Show how to draw a graph of the changes in temperature by joining the temperatures plotted on the graph. Can they read the graph? [The temperature rises from 8 a.m. to 1 p.m. then falls.] Explain how people in the Weather Forecasting Service read the temperatures every day to help describe the present weather and predict the future.
Recording sheet
Date Time 8 a.m. 9 a.m. 10 a.m. 11 a.m. 12 noon 1 p.m. 2 p.m. 3 p.m.
.
 Temperature 29oC 30oC 32oC 32oC 33oC 35oC 32oC 31oC
Extra Activity
During the next two days, each hour a pair of children must read the temperature, record it, and mark it on the graph sheet. After three days compare the patterns of temperature change. Do the patterns look the same? Are the maximum temperatures the same?
4.12 Smoke moves up and down
See diagram 23.2.7: Candle in a jar | See diagram 37.120: Candle in a jar
Be able to explain why smoke can move up and down.
Use one small candle about five cm long, a large jar with straight sides, a piece of cardboard cut in the shape of the inside the jar, a piece of paper for burning. Before the lesson fit the cardboard into the jar so that there is no space between the edges of the cardboard and the inside the glass. Leave a large space about two cm beneath the bottom edge of the cardboard and the bottom of the jar. In this experiment the air above the candle is heated, expands and rises drawing down the cooler air from the other side of the glass jar.
or groups
1. Light a piece of paper then put it out so that it makes smoke. Which way did the smoke move? [Up.] Can the smoke move down? You will do an experiment to see if you can make the smoke move up and down.
2. Show the jar containing the cardboard wall and the candle. What is on this side of the wall? [Nothing.] What is below the wall? [Nothing.]
3. Roll up a long piece of paper to make a lighted taper. Light the candle. Light another piece of paper then put it out to make smoke. Hold the smoking end over the candle side of the jar. What happens? [Smoke goes up.] Hold the smoking end over the empty side of the jar. What happens? [The smoke goes down.]
4. Let the children watch the smoke closely. In which direction does the smoke move through the jar? [The smoke goes down the empty side and up the candle side.] Let them feel the air above each side. BE CAREFUL! What do you feel above the empty side? [Nothing.] What do you feel above the candle side? [Hot air.]
5. Explain that the smoke goes wherever the air goes. Why does the smoke go down? [The air goes down.] Why does the smoke go up? [The air goes up.] Where does the air go from the candle. What does the air going up feel like?
Extra Activity
Tell them about smoke going up and down near fires at home. This will provide a real life experience. Sentence completion: Smoke moves where the air moves. Smoke goes [up] when the hotter air goes [up]. Smoke goes [down] when the cooler air goes [down].
4.13 Inertia tricks
1. Inertia with a stone
See diagram: 6.240
Use a stone weighing about 1 kg. Suspend the stone with a light string that is just strong enough to support the stone. Attach two pieces of the same string to the stone and let them hang down. Grasp firmly the lower end of one hanging string and give it a quick jerk. The lower string breaks and leaves the stone suspended because of the inertia of the stone. Pull steadily on the other hanging string. The upper string breaks and the stone falls. The steady application of force has set the stone in motion.
2. Inertia with two drink-can pendulums
See diagram: 16.241
Use long strings to suspend from the ceiling two large identical drink-cans or buckets. Fill one can with sand. Use the hook of a spring balance to push each can in turn. Note what force is necessary to start the cans moving. Use your hand to stop the cans when they are moving. You can feel the difference in inertia of the two cans.
3. Inertia with coin on card trick, pile of books
See diagram 16.4.8: Coin on card trick
Put a coin on a playing card placed over the mouth of an empty glass. Ask someone to remove the card but not the coin. Flick the card away quickly with your finger. The coin falls into the glass. The coin does not move sideways because of its inertia.
4. Make a pile of books. Grasp the book at the bottom of the pile and pull very quickly. You can remove the bottom book without upsetting the pile because of the inertia of the books above it.
5. Scoop up a spade full of dry earth. Pitch the earth away from you. When the spade stops, the earth keeps moving because of its inertia.
4.14 Prepare crystals
See diagram 35.8.3: Crystal shapes | See diagram 3.2.49: Crystal suspended in a solution | See diagram 3.2.50: Crystal crown
Be able to dissolve pure substances and make crystals.
You will need: Alum, Epsom salts, common salt, sugar, small spoons, a cup.
There are two main ideas here: dissolving and crystals. When substances are dissolved in water, you cannot see them. However, if you dissolve alum, Epsom salts, common salt or sugar, you can prove that these substances are still in the water because you can taste them. If you boil away the water from the dissolved substances by heating or leaving it in the sun then the dissolved substances reappear as crystals. Crystals have a glassy look and a certain shape and colour. However, the crystals of common salt or sugar you buy are mostly broken into small pieces. You will need: common salt, potassium permanganate (Condy's crystals) urea, magnesium sulfate crystals (Epsom salts) a container to boil water in, a flat dish, small spoons, a cup.
Be careful! Let the children taste sugar or table salt but not other crystals!
1. Show some common salt. Let them taste it. It tastes salty. Pour a few spoons of water into a cup. Stir some salt into the water and show this to them. Can you see the salt now? [No.] Is the salt still there? [Let them taste the water. Yes, you can still taste the salt.] Explain that the salt is dissolved in the water.
2. Add more salt to the water and keep stirring. When you can dissolve no more salt in the water, pour the water into two tin lids. Leave one lid in the sun. heat the other lid very slowly over a flame. What happens? [Water boils off, then crystals appear.]
3. Let the children look at the crystals with a magnifying glass. What did you see? [Shiny solids with flat sides, sharp corners, white colour.] Explain that all crystals are shiny, have flat sides, shapes and colours. Each kind of crystal has a special shape. Here is a sand (quartz) crystal. It has six sides.
4. Let the children make sugar crystals and observe them.
5. Look at the tin lid left in the sun. Do salty crystals appear? [Yes] Where does this happen naturally? [In rock pools near the sea.]
Extra Activity
Sentence completion: Crystals look like pieces of [glass]. They have straight [sides]. Each kind of crystal has a special [shape].
4.15 Pace distances
Be able to measure distances consistently using paces.
Before the lesson, find a medium sized child and tell the child to walk ten paces in a straight line. Mark this distance inside or outside the classroom and mark two lines at right angles to it at the start and finish. Make sure the children can count to twenty. Find two trees about fifteen child's paces apart.
1. Line up the children on the start. Walk steadily for ten steps, then stop.
2. Show the finish line. Some have stopped before it and some have stopped past it. Start again. You have to walk ten even paces and stop on the finish line. Let the children do this many times until they all have the same size paces.
3. Pacing Game: Divide the class into two groups. Send each group to a tree. Call out the name of one child in each group. When you say "go", the child walks towards the other tree counting the paces. The winners walk the same number of paces.
4. Divide the class into two groups outside the classroom door. Each group walks around the classroom in different directions and counting paces until they come back to the door. Is the number of paces the same?
Extra Activity
What is the length in paces of the football field, cricket pitch, a school playground? How many paces from school to home?
4.16 Air resistance
See diagram: 12.157: Air pressure umbrella
1. See the diagram of stick figures running with an umbrella
Which figure can run the fastest? Which figure is slowed most by the air? Which umbrella causes the most air resistance? Which umbrella caused the least air resistance?
2. Measuring air resistance
Use a cotton reel, a wooden stand, a large nail, thread, a weight and a piece of cardboard.
2.1 Cut four pieces of card all 5 cm wide and 5, 10, 15 and 20 cm long. 2.2 Cut a slit across one end of the cotton reel. 2.3 Push the nail through the reel. 2.4 To fit the 20 cm long card into this slit, cut a piece out of the card to fit round the nail. 2.5 Push the nail into the wooden stand so that the reel can turn easily. 2.6 Put the stand on the edge of a table.
2.7 Tie the weight to the end of a thread 2 m long.
2.8 Wind the thread round the cotton reel.
2.9 Use the second hand of a watch to record the time for the weight to drop to the floor.
2.10 Repeat the experiment with no card.
2.11 Repeat the experiment with the 5, 10, 15 cm cards.
2.12 Plot your results on a graph. The graph shows that a large surface has more air resistance than a small surface.
4. 17 Shapes game
See diagram 2.1.2: Shapes and order
Be able to compare different shapes and put them in order of size.
Use to cut out two cardboard squares with sides 10 cm for each group in the class. On one square draw the shapes as in the diagram. You can label each shape A to G or colour them. Cut out each shape.
1. Give each group a cardboard square and a pile of the seven shapes. Let the children play with them.
2. Are these shapes, C and E the same size or different size? [They are the same size. One shape can fit exactly on top of the other.]
3. Are these shapes, C and D, the same size or different? [C is smaller than D.] Can you make these shapes, C and E into this shape D? [Yes they can fit together to make D, see the diagram.]
4. Are these shapes, E and F, the same size or different size? [No, E is smaller than F.] "Can you make the shapes C and E into this shape F? [Yes, they can fit together to make F.]
5. Are the shapes, C and G, the same size or different size? [No, G is bigger than C.] Can you make the shapes C and E into shape G? [Yes, they can fit together to make G.]
6. Which shape is the biggest, D or F? [Neither, shape D is equal to shape C + shape E, shape F is equal to shapes C + shape E, so shape D is the same area as shape F.]
7. Which of these three shapes is the biggest, D, F, or G? [They are all the same size.] Can you make the shape A out of three smaller shapes? [Yes, out of F and C and E [see the diagram below.]
8. Can you arrange the shapes in order of size on the desk? [Yes, largest sizes are A and B, medium sizes are D, F and G, smallest size are C and E.] Can you fit all the shapes together on top of this shape, the plain cardboard square? [Yes, see first diagram.]
Extra Activity
The names of the shapes:
Square (4 sides and 4 corners, angles are all the same)
Triangle (3 sides)
Parallelogram or "squashed square" (4 sides and 4 corners, opposite angles are the same).
Find the following shapes in the classroom and in the school buildings - square, triangle, parallelogram (squashed square).
4.18 Diameter of a thread
See diagram 2.1.7: Estimates, See (3)
Wind thread around a ruler to cover 2 cm of rules. The number of winds = W, The diameter of the thread = 2/ W.2. How many pages in a book? How thick are all these pages, one on top of the other? How thick is one page?
4.19 Prepare invisible inks
1. To make brown writing, squeeze lemon juice into a bowl and add water to make the invisible ink. Write a secret message on thick paper or unglazed paper, e.g. drawing paper, using a wide tipped pen or a toothpick. As soon as the ink dries it becomes invisible. Send the secret message to someone who knows the secret of reading it! Hold the secret message over a hot light bulb or near a candle flame. The ink becomes brown and the message can be read. Juice of lemons contains many carbon compounds such as sugars. The heat breaks down the sugars and other compounds into water and carbon. Pure carbon is black. The water leaves the paper as water vapour or steam and the carbon remains. The writing is brown not black because the carbon is not pure. You can also use milk, sugar solution, onion juice, and even your own saliva!
2. To make black writing, dissolve alum [potassium alum, AlK(SO4)2.12H2O] in water and use as above. You can also use dilute sulfuric acid, sodium hydrogen sulfate, and copper (II) sulfate.
3. To make blue writing dissolve red cobalt chloride crystals in water to give a pink to colourless solution. The writing is invisible on pink writing paper but when you warm the paper it appears brilliant blue. You can make the writing disappear by breathing on it but it will reappear when you warm the writing paper again.
4. To make transparent writing use wax or a small piece of candle. The writing is invisible until you warm the paper.
5. Put one drop of oil and 1 cm of 880 ammonia solution in a test-tube. Add water and shake the test-tube. Use the solution to write on paper with a paint brush. When the paper is dry the writing becomes invisible. To see the writing again, dip the paper in water.
4.20 Measure chest expansion
See diagram 9.242: Lungs in the chest
Be able to measure chest expansion and explain the reason for this movement.
Use a tape measure, practice measuring your own chest after inhaling and after exhaling. Measure your chest where it is widest.
1. Stand up and push one finger into your stomach up and under the lower rib. What can you feel when you breathe in? [The finger is pushed down by the diaphragm muscle.]
2. Show how to measure their chests. Note the chest measurement after breathing out. [About 70 cm.] Note the chest measurement after breathing in. [About 74 cm.]
3. Tell the children that the different measurements are caused by the chest expanding and contracting to air into lungs and push it out again. Measure again after breathing really hard out and in.
4. Which child has the biggest chest expansion? [Chest expansion = (breathe in measurement) - (breathe out measurement).] How did the chest get bigger? [Ribs move up like the handle of a bucket just when the diaphragm muscle drops down.]
Extra Activity
How often do they breathe in and out in a minute?
1. when sitting quietly,
2. after running? Does the chest expansion change? [Yes, chest expansion is greater after running.]
4.22 Memory games
Be able to improve the memory of the position of things by using these memory games.
If the school does not allow playing cards, make memory cards with symbols, e.g. black and white triangles or other symbols.
1. Pelmanism
Spread playing cards face down. The players sit around them. The first player turns up two cards, e.g. a 7 and a 10, lets the other players see them, then turns the cards face down in exactly the same places. The second player turns up two more cards, e.g. a king and a 10, then turn the cards face down in exactly the same places. The third players remember where the two tens are and turns them face up. That player wins one point, removes the two tens, and has another go by turning up two more cards. That player first turns up a king but cannot remember where the previous king was, and turns up a jack. Then the fourth player turns up two cards. The game finishes when all the cards have been turned up in pairs. The player who has turned up the most pairs wins.
Method: Groups of four children - two pairs of players.
Each group plays, the winning pairs of players play the other winning pair until they find the champion pair in the memory game. 2. Instead of playing in pairs, each person can play separately.
Extra Activity
Organize a memory game contest in the school. Let children take their memory cards home to play with their families.
If the school does not allow playing cards, make memory cards with symbols, e.g. black and white triangles or other symbols. Make two of each, the 20 cards should all be the same size. In this game, two black triangles is a pair and wins one point. However, a black and white triangle are not a pair. You can teach the children to make these cards.
2. Kim's game
Put ten different objects on a tray, e.g. pen, comb, orange, ruler, spoon, chalk, scissors, cup, bottle, glasses. After one minute remove the tray and ask each person to write a list of the items. Bring back the tray and give each person a mark out of ten. A memory trick is to make connections between the objects. For example three items begin with "c". You can write with two items.
4.23 Test your reflexes
Be able to show some movements of the body called reflexes.
You think that you control all the movements of your body. If you want to pick up a pencil, you can move your arm and fingers to pick it up. My arm and fingers do not move unless I want them to move. Sometimes something happens to the body and then it has to move faster than you have time to think about it. Also, some movements inside the body must be automatic, e.g. after a big meal you can sometimes hear a rumble in the stomach when it lets partially digested food pass into the intestine. These automatic movements are called reflexes. They are one function of the nervous system.
Method: Groups of two children.
1. Work in pairs. The first person will do something to the second person, then you will see what the second person does.
2. Stare into each other's eye Do the eyes move? [Yes, the eyes blink.] Did you try to make them blink? [No, it just happened.]
Wave your hand in front of the person's eyes. Did you make them blink? [Yes.] Did the second person try to blink? [No.] Why did the second person blink? [Because they saw the waving hand.]
3. Tickle the arch of the foot. What happens? [The big toes wiggle.] Why did you try to wiggle your toe? [No, It just happened when my foot was touched.]
4. Sit on the desk with the knee just over the edge. Let the leg below the knee swing slightly. See the place just below the knee cap. Hit this place sharply with the side of the hand. What happens? [Leg swings up. This is called the "knee jerk reflex". Why did your leg straighten? [It just happened when I was hit below the knee cap.] Which child has the fastest or biggest knee jerk reflex?
Extra Activity
Are there any other reflexes? [ Kick your toe, reflex: shift weight on to the other foot.]
Stand on one leg. The reflex is to wave your arms to help balance.
Hold your breath for a long time. The reflex is to breathe. You cannot stop yourself breathing in.
4.24 Speed of reaction
See diagram 9.249: Dropping the ruler
Objective: To observe how fast you can react to a change.
You will need: sheets of line paper, rulers, stones and paper clips. These activities are designed to give children practice in improving the speed of their eye and hand co-ordination.
Method: Groups of two children.
1. Grabbing the stone
One child holds a small stone in his open hand. The other child tries to grab the stone before the first child can close the hand. Now one child changes hands, then the other child changes hands. Put a tick in the table of results if the stone is grabbed two attempts out of three. Then reverse the situation.
2. Dropping the stone
One child holds the top of a ruler in one hand and a stone in the other. The other child holds his hand at the bottom of the ruler. The first child drops the stone and the second child moves the hand away so that the stone does not hit it. How close to the hand can the child drop the stone and not hit the hand, answer in centimetres. Which child has the fastest speed of reaction?
3. Catching the ruler or catching the sheet of paper
Attach a weight to the end of a ruler or piece of lined paper. Hold it at the bottom between thumb and first finger. Let it go, then catch it again. What is the smallest distance between letting go and catching it again? What is the connection between distance and speed of reaction? [The smaller the distance the faster the speed of reaction.]
4. Hold the end of a ruler so that it hangs down vertically with the zero in line with the thumb of an outstretched hand. Drop the ruler through the space between the thumb and fingers held wide apart. Record the distance that the ruler fell before it was caught. The distance the ruler fell is called the reaction distance, i.e. the length of the ruler that fell between the fingers before it was caught.
5. Use the thumb and index finger to hold the bottom end of a vertical ruler. The zero on the ruler must be in line with the thumb. Open then close the thumb and index finger as quickly as possible. Record the distance the ruler travelled as an indication of the reaction distance.
Extra Activity: To play the stopwatch game you need a stopwatch. The game is to see how quickly you can turn the stopwatch on, then off again.
4.25. Uses of peas and beans
See diagram 9.72.1: Legumes | See diagram 9.53.9: Acacia, Leucaena
Be able to recognize different plants in the bean (legume) family.
Collect two examples of legumes that are 1. food plants, e.g. peanuts, 2. cover crops or green manure, e.g. Centrosema and cowpea. Examine the plants and discover the similar characters. Find out for yourself the characters of the bean (legume) family.
1. Legumes are plants of the bean family (Fabaceae). Most of the plants have lumps on their roots called nodules. Bacteria called Rhizobium can live in these nodules and use nitrogen gas from the air. When the legume plant dies and rots this nitrogen can be used by other plants. In this way legumes improve the fertility of the soil. When a legume crop is buried into the soil it is called a green manure.
2. Legumes are easily recognized from the leaves and the flowers. The leaves are usually compound leaves, often with each leaf divided into 3, five or more leaflets. The flower contains five sepals and five unusual petals, one large petal coming from the back, two wing petals at the side and two keel petals that may be joined below. There are 10 stamens stuck together to form a tube. The fruit is a pod formed from one carpel that can break into two to let the row of seed out. The flowers are normally self pollinated, but you can be cross pollinated by insects such as bees and butterflies that can push down the keel petals and get into the flower.
3. Legumes are an important food. Pulses, e.g. split peas, are easily digested and nutritious food. They contain about 20% protein, 60% carbohydrates, 3% fat and minerals, especially calcium and phosphorus, and vitamins. The type of protein is not enough for a balanced diet, so some animal protein is still required in the diet. Before cooking, pulses should be soaked in warm water overnight and the water thrown away. This reduces production of gas during digestion. They are cooked by boiling for up to an hour.
4. Give each group one of each kind of legume and some plants that are not legumes. Look at all the plants carefully and then make a set of plants that have similar characters. Go to each group and help them make their set but do not tell them the answers. Walk around from group to group to compare the sets. 2. Show the correct sets. List the common characters of the set: shape of leaves, shape of the flower, the number of parts in the flower and the nodules on the roots. The set of plants which look the same are all members of the legume or bean family. Find other legumes in the garden and in the bush.
5. The roots have lumps on them called nodules. These nodules contain bacteria called Rhizobium that can use nitrogen gas from the air. When the plant dies this nitrogen in the plant can then be used as plant nutrient by other plants.
6. The parts of the legume plants eaten by humans include: 1. tender young leaves, e.g. pigeon pea, 2. unripe pods picked when still green or light yellow, e.g. cow pea, 3. dried seeds called pulses, e.g. soya bean, mung bean, pigeon pea, chick pea, 4. sprouted seeds, e.g. mung bean 5. tuberous roots, e.g. winged bean. Legumes are used for food in two main ways: 1. The unripe green pods and sometimes also the tender green leaves are picked and cooked as a vegetable. These provide vitamins and minerals if eaten soon after picking, e.g. green bean, winged bean. 2. The pods are picked when almost dry before you split and let the seeds out. They are then dried in the sun and threshed by putting them in a bag and hitting it with a stick. The dried seed called a pulse is stored and later boiled and eaten, e.g. mung bean, pigeon pea.
7. Legumes may be grown between tree crops to cover the soil and stop weeds growing by shading them. These crops are called cover crops, e.g. the trailing plants Pueraria and Centrosema. Erect plants such as Crotalaria and cow pea are grown as green manure. If these plants are dug into the soil at the time of flowering nitrogen plant nutrient is added to the soil. Some legumes that are trees or shrubs are grown to provide shade or windbreaks, e.g. Leucaena
8. Legumes that are large trees and have large flowers are grown for shade and decoration, e.g. Erythrina.
4.26. Legumes
1. Winged bean or four angled bean or Goa bean (Psophocarpus tetragonolobus). This bean should be grown in all school gardens because the seeds have a high protein content. You can eat the seeds, green pods, leaves, flowers and tubers.
2. Cow pea, snake bean, yard long bean (Vigna): These plants are closely related. They are grown for the seeds and pods and as a green manure crop.
3. Peanut or groundnut (Arachis hypogaea): They have a high protein content and the plant is a good animal feed. The peanuts must be roasted or boiled before eating. Some children are allergic to peanuts so be careful!
4. Mung bean or green gram bean (Phaseolus aureus): The pods have a high protein content and the seeds can be left to sprout rather than eaten. The pods are small. It is also a good green manure crop.
5. Soya bean or soy bean (Glycine max): The seeds are very nutritious but this plant is attacked by lots of diseases in the wet tropics.
(f) Chick pea (Cicer arietum): It has a perennial bush that can be used as temporary shade.
7. Other shade trees: "cocoa shade" (Gliricidia albizia) coral tree (Erythrina) Leucaena, wattle tree (Acacia) golden shower Cassia and Poinciana or the flame of the forest (Delonix regia). 8. Other useful legumes: Lablab bean, yam bean (Pachyrrhizus) and Derris used to make an insecticide and fish poison.
1. What are the different kinds of legumes you know? Write down the local names and common names on the chalkboard.
2. What are the different uses of legumes? The uses of legumes are food for people and animals, cover crops, green manure crops, shade and windbreaks, flowering trees.
Extra Activity
Bring samples of legume pods to class for a class display.
Pasture legumes
Common name Variety Uses
Calopo - Pioneer legume, vigorous growth for weed control.
Centro Common Belato Suited to tropical lowland environments, grows slowly. Hard seeds take a long time to germinate.
Hetero Johnstone Suited to wet tropical coast. Combines well with Pangola and Signal Grass.
Desmodium Greenleaf Combines well with grasses in coastal areas of tropics.
Puero - Pioneer species, palatable and productive. Grows well in shade under trees. Large rounded leaves.
Stylo Scholfield Adapted to humid tropics, even poor soils.
Leucaena Peru Perennial shrub. Combines well with signal grasses.
Siratro - Easy establishment. Prolific grower, persistent. Makes thick mat. Flowers dark red turn purple.
4.27 Collect bean plants
See diagram 9.72.1: Legumes
Objective: To make a permanent collection of different types of bean plants. You will need: lots of newspaper and a heavy weight or press. Before the lesson, ask each child to bring three bean plants: 1. one food crop plant, e.g. peanut or mung bean, 2. one pasture legume, e.g. Centrosema or Crotalaria, 3. one bush plant, e.g. Acacia, Leucaena, Canavalia.
1. Arrange your plants on the desk. How do you know that these plants are legumes? [By the shape of flowers, pods, divided leaves, nodules on roots.] 2. Attach a piece of paper to each stalk and tell the children to write the name of the plant, their names and the date. Pull off any extra branches so that the specimen is quite small. 3. Put each child's plant inside a piece of folded newspaper. Put all these together in a pile. On top of the pile, place a piece of wood or cardboard. On top of this place weights or heavy stones. This is the way to keep plant specimens. Change the plant every few days.
Extra Activity
Take the specimens out of the plant press. Set up an exhibition of different types of bean plants. Ask each child to state the uses of the pressed plant specimens.
4.28 Bean life cycle
See diagram 9.112: Epigeal germination | See diagram 9.3.5: Epigeal germination
Be able to identify the stages in the life cycle of the bean plant.
Collect leaves and branches or whole plants, flowers, pods and seeds of any common legume. Explain the difference between annual and perennial life cycles. Small plants, e.g. peanuts, mung beans are usually annuals, the plants die after the seed has formed and scattered. Large plants, e.g. pigeon pea, flame of the forest, are perennials that produce seed for many years.
Show the bean plants, flowers and seeds. Draw the life cycle of the bean plant on the chalkboard. The male parts and the female parts of a flower are used to make baby seeds inside the bean pod.
4.29 Bean flower
See diagram 9.72.4: Winged bean flower
Objective: To pull apart a bean flower and state the function of this kind of flower. You will need: at least two large bean flowers for each child. In this lesson it is important that each child learns to pull the flower apart and see the individual pieces. Make sure you understand the diagram below before trying to teach this lesson.
1. Push your fingers inside the flower. Can you see the parts inside like little sticks? These little sticks are the male and female parts. Look at these parts: 1. flower stalk
2. Sepals are like little green leaves which cover the bus and protect it.
3. Petals have bright colours and attract insects and sometimes birds.
4. See one big petal at the back (standard).
5. See two petals at the side (wings).
6. See two petals at the bottom (keel) which may be stuck together.
Pull off the sepals and petals. The male parts (stamens) are like little sticks with yellow knobs because of pollen. Pull off all the male parts. The female part is what is left. It looks like a small bean (ovary) with a stick and knob at one end (style and stigma). Open the female part. Can you see little white seeds inside? [They are the ovules, not seeds.] When the yellow pollen from the male part gets onto the female part then little baby seeds are made.
Draw a diagram of a cross-section of the flower.
Extra Activity
Draw the individual parts of the bean flower.
4.30 Bean seeds and pods
See diagram 9.113.1: Bean pod
Be able to 1. examine the outside and inside a bean seed and 2. recognize the parts of a bean seed and say what they are used for.
You will need: soft pea or bean pods and bean seeds. The seeds must be soaked in water a day before you teach the lesson. Each seed is covered with a seed coat and you can see the scar where the seed was attached in the seed pod. Inside the seed coat are two cotyledons or halves that contain stored food. This food is used by the young plant when it first begins to grow, i.e. germinate. The young plant lies between the two seed leaves and can be clearly seen with a magnifier. It consists of a young root and a young shoot, leaves and stem.
1. Give each group one magnifier, four bean seeds and four sheets of paper. Open some pods show the seeds inside to them. Take one bean seed, look carefully at the seed and feel it, notice that the seed has a "skin" or coat around it called the seed coat that protects the seed. Use the finger nails carefully to cut through the seed coat and remove it. Look carefully at the inside part of the seed. How many parts can you see? Cut carefully around the edge of the seed and open the seed into two parts. Show this to the class. Look for the small plant inside, take turns using the magnifying glass to look at the small young plant. 2. Look at the two big white parts (cotyledons) and explain to the children that these contain food for the young plant when it begins to grow. The reason you eat seeds such as beans is that they contain growth food and healthy food.
Extra Activity
Draw a picture of inside the seed.
4.31 How seedlings grow
See diagram 9.103.2: Watch seedlings grow
1. Watch some young seedlings grow into mature plants. Look for changes in colour, height and the number of leaves. Measure the size of the leaves. Count the flowers and the fruits. Keep records of your observations.
2. Tie a string around the growing stem at an exact distance from the end of the shoot tip, e.g. 2 cm. Record the distance between the end of the shoot tip and the tied string every day. You can see that plants grow by extending their shoot tips.
3. Measure the height of the seedling with a ruler. Cut a strip of paper the same height as the seedling and paste it on a big piece of cardboard. Do this each day to make a bar graph. Use the bar graph to predict how tall the plant will be 5 days later. If you join the middles of the tops of the bars, you have a line graph. When the slope of the line is steep, the plant is growing fast. When the slope of the line is flatter, the plant is growing slowly.
4. Compare the growth of two seedlings, bean and maize. Which seedling starts to grow first? Which seedling is tallest after twelve days? On which day are both seedlings the same height? With this kind of graph you can answer questions, e.g. Do plants grow more during sunny or cloudy days? Do plants grow more quickly when they are very young?
5. Compare the growth of four seedlings, tomato, chilli, pumpkin, papaya The four plants grow taller, produce flowers, fruits and seeds but they do these things at different times. Which plant germinates first? Which plant flowers first?
4.32 Weathering rocks
See diagram 6.04: Plant roots split rock
Be able to explain how rocks are broken down into small pieces by the weather.
Use some rocks that break easily, some large tins, or river sand. The children should learn that rocks do not stay as they are. They can breakdown to smaller pieces.
1. Give each group a large tin and some rocks. Look at the rocks closely and feel how hard they are. Put the rocks in the tin and shake them together. Tip out the tin. What do you see? [Pieces of rocks and sand.] Where did the small pieces come from? [From when the rocks hit each other.] Shake the rocks together for a long time. What happens to them? [They breakdown into sand.] What can move stones or sand? [The wind, water in a river, the sea.]
2. Heat rocks in an oven then drop them in cold water. The rocks break into small pieces or the corners break off.
3. Can anything else breakdown rocks? [Tree roots can break a rock apart.]
4.33 Make sedimentary rocks
Be able to show how sedimentary rocks are formed.
Use samples of sedimentary rocks such as conglomerate containing large and small stones and sand cemented together. Also, have some sedimentary rocks that have distinct layers. Small stones, sand, colour rocks, flour or plaster of Paris, glass jars.
1. Remind the children how rocks can be broken into pieces and sand. Show the stones and sand you have collected. Explain that the small pieces and sand can be squeezed together to make rock again. Show children the sedimentary rocks. Can you see the different size stones in them? Can you see the bands of rocks? Explain in this lesson how you can make a rock again.
2. In one container put sand, a little water, flour or plaster of Paris, and blue ink. Mix and pour into a glass jar. In another container put stones, water, flour or plaster of Paris with red ink. Mix together then put into one glass jar. Can you see another new "rock" formed in two layers?
3. How are sedimentary rocks made naturally? [Small pieces of rock are squeezed together at the bottom of the sea.]
Extra Activity
Collect sedimentary rocks from the local area.
4.34 Protect soils
See diagram: 6.62: Protecting soils on slopes
Be able to explain how soils can be protected from being washed away.
In this lesson you are concerned with the natural soils in the bush or fallow soils that can be used again after 5-7 years or more. Some people use land again too soon before the traditional forest fallow has restored the plant foods in the soil. Remember that when water runs over bare soil it not only removes the topsoil but also washes out the plant foods such as potash.
1. Explain that your country is rich because it has lots of good soil. However, if you do not protect the soil it will be washed away. Then you will not have enough soil to grow crops you need for your food or to sell. Soil that is not used is called fallow.
2. The soil must be protected from heavy rain and water washing over it. The best protection is a cover of plants. Plants protect the soil in three ways:
2.1 Their leaves stop the heavy rain from hitting the soil washing it away.
2.2 The stems and the leaves stop the water rushing over the soil. They slow the water so that it soaks into the soil.
2.3 The roots hold the soil together and stop the water from washing it away, and washing away plant foods.
3. You can help the small trees and bushes to grow on the fallow soils in the following ways:
3.1 Do not burn grass or bushes.
3.2 Plant trees or Leucaena, especially on steep slopes.
3.3 Plant cover crops, e.g. creepers such as the legumes Pueraria or Centrosema.
3.4 Build a fence around the land so cattle or goats cannot eat all the plants. Do not clear the bush until just before the planting again.
4. Other ways to protect the soil
4.1 Dig drains to carry water away from the garden land quickly.
4.2 Do not build roads on steep slopes, the water runs off the roads and washes the soil away.
4.3 Make dam walls across the slope of the land using stones and trees to catch and hold any soil washed down.
Extra Activity
Show places where the soil is washed away and should be protected. Discuss how to protect the soil in this place by helping to plant cover and draining and terraces.
Sentence completion: How do plants protect the soil during fallow? 1. Stops rain [hitting] the soil, 2. Stops water [running over] the soil, 3. Stops water [washing away] the soil.
4.35 Natural fertilizers
See diagram 6.65.1: Nutrient cycle 1 | See diagram 6.65.2: Nutrient cycle 2
Be able to explain how to make and use different kinds of natural fertilizers.
You will need: Soil, plant ash, manure, food wastes and cut grass. In traditional agriculture, people cut down and burn the forest, plant crops, farm the land for a few years, then regeneration of a secondary forest for 5-12 years before using the land again for crops. This method of bush fallow is using natural fertilizers to improve the soil. You can speed up this method and grow crops more often by using the following methods of natural fertilizing. White plant ash is mainly potash.
1. Explain the traditional methods of natural fertilizing. How long is the fallow period in your area? Explain that by using the following methods the use of natural fertilizers is improved and you can grow crops more often on the same piece of land.
2. The methods are as follows:
2.1 composting and mulching,
2.2 plant ash,
2.3 green manure,
2.4 liquid manure.
3. Composting means to make a compost heap on the ground out of layers of different wastes that can rot. Such wastes include onion, plantain and yam peels from the kitchen or any soft wastes for that matter. After how many days does their own heap start to lower in the soil?
4. If mulch covers the soil for a long time, the bottom layer becomes rotten compost. Do not dig mulch into the soil unless it is rotten.
5. White plant ash (potash) contains plant food. Burn old leaves and stumps until all the black charcoal is gone leaving only the white ash. Spread it evenly over the soil. Rake or dig it into the soil, do not let it blow away or wash away. Compare this with what happens in farm lands or when farm land is cleared for local housing.
6. Green manure is made from local leguminous plants that grow and can be easily dug into the soil, e.g. cow pea and Crotalaria. Digging in is hard work. When these plants rot in the soil they fertilize it.
7. Liquid manure is used for small individual plants that may be burnt if you use new chicken manure or pig manure. Fill a steel drum with water and throw in any animal manure. Keep a lid on the drum because it will smell. If you pour some manure liquid on the soil, the plants will grow fast.
Extra Activity
Take the children on a garden walk to see the four methods of using natural fertilizers.
Sentence completion: The four methods of using natural fertilizer are as follows: 1. [Composting and mulching] 2. [Plant ash, potash] 3. [Green manure] and 4. [Liquid manure]. When plants and manure [rot] in the soil they return the [plant foods] to the soil.
4.36 Water climbs up soil
See diagram 6.36: Water climbs up
Be able to show that water can move up in soil.
Use to prepare some fine soil and some coarse soil dried in the sun. Hit the soil sample with a hammer or stone to break up any lumps. Plastic tubing 10 cm long or small thin glass jars or drinking glasses that you can fill with soil. Also, you will need large jars or deep plates. Tin can with holes in the bottom. Half fill it with soil.
Method: Groups
1. Show the tin can with holes in the bottom. Half fill it with soil. Add water to it. What happens? [Water comes out of the holes.] Which way did the water go? [Down through the soil.] Can water go up in the soil? Let us do an experiment to find the answer.
2. Give each group 2.1 dry soils, 2.2 tubing or small jars, 2.3 large jars or flat plates. Feel the two samples of soil. What is the same about them? [Both feel dry.] What is different about them? [One feels rougher because the particles of soil are larger.]
3. Fill the tubing or small jars with soil. Put this into the large jars or plates. Put more soil in the large jar or plate. Add the same amount of water. Now watch the soil very carefully. What do you see? [Water climbing up the soil.] In which soil is it climbing up the fastest? [The soil with the smaller particles.] In which soil does the water climb the highest? [The soil with smaller particles.]
4. Which kind of soil has the largest particles? [Sandy soil.] Which kind of soil has the smallest particles? [Clay soil.] If a plant uses all the water near the surface of the soil how can it get more? [Water climbs up.] In which soil can water climb up the highest? [Clay.]
Extra Activity
Note that the time taken for water to reach the top of the tubing. How fast can the water move in one hour? Sentence completion: When you add water to the surface of soil it moves [down]. If dry soil is above wet soil water moves [up]. The water moves [faster] and [higher] in [fine] soil than in [coarse] soil.
4.37 Soil water bottle
To compare the amount of water in soil, fill a large bottle with water, put your finger over the end and push the end deep into the soil. The level of water in the upside down bottle will drop. To compare soils use same size bottles to see different levels of water for comparison. The soil water bottle can be used to slowly water a small garden. As water is used by the plants or lost by evaporation water comes out of the soil water bottle.
4.38 Liquids in the sun
Be able to describe what happens when different liquids are left in the sun.
You will need: three containers the same size, two containers (one much wider than the other) salt, kerosene or methylated spirit, ruler. Recall the theory and practical aspects of the fact that when evaporation occurs there is a heat loss. An easy example is the evaporation of sweat from your bodies after exercise and the crystallization of salt in the process.
1. Put water, salty water and kerosene or methylated spirit in similar containers in the sun. measure the depth of liquid in each with a ruler and note the time. After a few hours measure the depth again and note when each container becomes dry. What is left in the dry containers? [Salt in one and nothing in the others.]
2. Loss of liquid due to heat is called evaporation. Put the same volume of water in a tall and shallow container in the sun. Measure the depth in each after a few hours. Which loses water fastest? [The shallow container because it has the greatest surface area.]
Extra Activity
Show that when evaporation occurs heat is lost. This is how you cool when water evaporates from your skin. Taste some sweat. How does it taste? [It tastes salty. The water has evaporated leaving the salt behind.]
4.39 Melt different solids
See diagram 23.30: Heating stand
Be able to describe what happens when different solids are heated.
Use tin lids, burners or candles, heating stands, sets of materials for heating, candle wax, stone, Plasticine, clay, rubber, sugar, common salt and red cooking oil, coconut oil or margarine. Once the materials have melted them should stop heating. The liquid formed should not be allowed to boil. Hard substances such as stones and common salt can melt at very high temperatures. Coconut oil melts at a very low temperature.
1. Show how to heat the solids on a tin lid over a flame. Heat one solid that melts and explain the words "melts" and "melting". A solid becomes a liquid when it is heated.
2. Give out the materials and tell the children to heat each item in turn on the tin lids and watch carefully to see if each substance melts or not. What happens in each case and make two lists on the chalkboard?
3. Note what happened when the melted solids were left to cool. Solids that melted to form liquids. Solids that did not melt. (ice, stone, coconut, oil, rubbe,r candle wax, common salt, red cooking oil, clay OR Melts What happens to the melted solids when they are not heated? [They cool to form solids again.] Some substances such as cooking oil usually remain as liquids. In the tropics some brands form thick solids. Melted ice blocks will not become solid unless put back into a freezer where the temperature is very low.
Extra Activity
List all solids and liquids at home. Sentence completion: When you (heat, cool) some (solids, liquids) they change into (solids, liquids). A solid that melts easily is (stone, wax, coconut oil). A solid that does not melt is (stone, wax, coconut oil). [When you cool some liquids, they change into solids. A solid that melts easily is coconut oil. A solid that does not melt is stone.]
4.40 Heat and cool water
Be able to describe what happens when liquids are heated to boiling then cooled.
You will need: Burners, lids of tins, bottles, water.
Steam is actually a mixture of liquid and gas called water vapour. You cannot see water vapour but you can see steam. There can be no steam unless water is heated.
1. Give out materials and tell the children to heat an empty tin lid until it is very hot. Dip one hand in cold water then let the water drip onto the hot tin lid. Do this several times. What did you see? [Steam forms from the drops of water.] What did you hear? [A hissing sound.] Where has the water gone? [Into the air as steam when the water boiled and changed into steam.]
2. How did you could find out where the water has gone [Do the following experiments.] Boil water in a tin. What do you see? What do you hear? [Bubbles form.]
3. Pick up an empty bottle and describe how it feels. [Cool and dry.] When the water boils tell the children to hold the cool dry bottle above the boiling water in the tin and watch very carefully. Look at and feel the outside the bottle. What do you feel? [The bottle is wet.] Where is the water on it?
4. Where the water comes from the steam? Where did the steam come from? [From the water.] Why did the water change into steam? [It was heated.]
5. What happens first when you heat a solid? [It melts and changes into a liquid.] What happens when you heat a liquid? [It boils.] Where did the liquid go? [Into the air, it became a gas.] What word do you use when a solid change into a liquid? [Melts.] What word do you use when some liquid bubbles and goes into the air? [Boils.] Where did the water go? [It turned into steam.] Solid and heat forms liquid and more heat forms gas, gas cools to form liquid cools to form a solid.
Extra Activity
Boil some water very slowly. Where do the bubbles form first? [On the bottom, near the sides.] Why? [The water nearest the bottom absorbs heat first, then bubbles stick to the sides of the tin.]
Sentence completion: Match the letters 1.2. 3. with the numbers 1, 2, 3 1. Solid to 2. liquid to 3. gas 1. steam or water vapour 2. ice 3. water [Answer: 1. 12. 3 3. 1.]
4.41 Ice experiments
Put an empty jar or beaker on each table. Only the teacher touches or handles the thermometers!
1. Melting point or freezing point of ice / water at zero degrees Celsius, 0oC.
Draw temperature scale near 0oC on chalkboard
1.1 Place a thermometer in each empty jar. Ask children to read the air temperature in degrees Celsius, e.g. 20oC. Add crushed ice to each jar then adjust each thermometer so that the thermometer bulb is surrounded by crushed ice. Ask children to read the thermometer. Children observe the temperatures falling to 0oC. then stops.
1.2 Add salt to each jar adjust each thermometer so that the thermometer bulb is surrounded by crushed ice. Children observe the temperature falling to less than 0oC. A mixture of salt and ice is called a freezing mixture.
2. Ice floats in water
2.1 Demonstrate an ice cube floating in fresh water. Do heavy things or light things float in water? (Light things.) So ice is lighter than water.
Remove the thermometers from the jars then add water to the crushed ice and salt. Give children an ice cube to feel then put into the jar. Ask children to observe floating ice and estimate how much is above the level of the salt water. (About 15%.) What floats in the antarctic ocean? (Icebergs.) Where do the icebergs come from? (Glaciers, that are rivers of ice.) Are icebergs made of fresh water or salt water? (Fresh water.) Is the antarctic ocean fresh water or salt water? (Salt water.) The surface layers of the ocean can freeze to form sea ice at about -1.8o.
[Extra: Show that an ice cubes floats higher in salt water than in fresh water]
2.2 Show children a glass jar with metal lid. If you cannot open the jar what do you do? (Put the jar under a hot tap water then try again.) Why can you now open the jar? (The heated metal lid expands more than the glass jar.) So heated things get bigger, expand, and cooler things get smaller. However, we saw the temperature of crushed ice was less than the air temperature so how can ice float on water?
3. Freezing water dance
3.1 Make human water. A girl is oxygen with two arms held like the handle of a teacup. A boy is hydrogen with one arm held like the handle of a teacup. Oxygen gas in the air is like two girls with both arms linked. Hydrogen gas in the air is like two boys with one arm linked. To make water, each oxygen girl links arms with two hydrogen boys.
3.2 At room temperature, the “waters” turn round and round, turning close together. As the temperature drops they turn more slowly. At 0oC. they almost stop turning, line up side by side and the hydrogens use the unlinked arm to push the next water away. When all the waters are lined up side by side and not moving the water has turned to ice.
H-H-H-H
O O O O
H-H-H-H
3. Freezing water expands
3.1 Homework experiment 1 (Tell your mother about the experiment.) or School supplies ice cube tray containing ice cubes
Fill an ice cube tray with water to make separate ice cubes and put it in the freezer. The next day the level of the ice cubes is higher than the former level of the water. So water expands when it freezes to form ice, the ice becomes lighter than water and can float in water.
3.2 Homework experiment 2 (Tell your mother about the experiment.)
Put water in a plastic dish Dry two ice cubes with a tea towel and put them in another plastic dish. Put the plastic dishes in a microwave oven and turn on the oven for one minute. Take out the plastic dishes then feel the temperature of the water and ice cubes. The water feels hot. A little ice has melted but the ice feels cold. The water in the ice cannot turn around so it is difficult to defrost food in the microwave oven.
4. Pressure melts ice
4.1 Give each child two ice cubes and tell them to push them together. The ice cubes stick together. Push them all together to form one long ice cube.
4.2 Put weighted wire on an ice cube. The wire cuts down into the ice cube because the ice under wire turns to water. Note the water next to the wire.
4.3 Put a thread (or match stick) over an ice cube and sprinkle a little salt over the thread. Pull down on the thread until it sinks into the ice. Wait for a few minutes then pick up the ice cube with the thread! Feel the little holes on the surface of the ice where the salt landed. The ice around the thread melted then froze again.
4.4 Snow is flakes of ice or ice crystals. In a snow fight do not squeeze a handful of snow and then throw the frozen snowball because it is solid ice. The ice in a glacier comes from snow squeezed together by its own weight.
4.42 Sundials
See diagram 36.68: Shadow stick sundial
Be able to describe the movement of the sun during the day.
Use to think about how children can record the position of the rising and setting sun. Observe the position of the rising and setting sun from the shadow stick in the school grounds. The children should make their own observations at home. Find a suitable place for a shadow stick in the school playground. It can be the school flagpole with a marker tied to it one metre above the ground, or a vertical stick one metre high. From the shadow stick, you can probably see the east and west for some distance. This lesson should be taught each side of midday. Before the lessons, observe where the sun rises and sets from the shadow stick, e.g. the sun rises at 6:30 a.m. over the big Kapok tree and the sun sets at 6:35 p.m. over the broken coconut tree near the store. They do not need to know compass directions. Before the lesson, tell the children to notice where and when the sun rises and sets from their own home. At midday (noon) the sun is at its zenith, it is directly above you and is at an angle of 90 degrees to the horizon. The shadow is nearly north to south, outside between 11:00 a.m. and Noon.
1. Where and when the sun rises and sets looking at it from their own house. Take the children outside and show them where the sun rises and sets looking from the shadow stick in the school.
2. Stand up straight and hold their arms out straight, palms down, hand palm touching the back of the hand. Now tell them to keep their right arm horizontal, raise the left arm until the left hand is pointing straight at the sun.
3. Be careful! Do not look at the sun! Do not look at the sun with dark glasses!
Can you see the angle between the two arms? [About 80 degrees.] 3. Hold both arms horizontal again, left hand over right. Point the arms at the place where the sun rises in the east. Use their left hand to trace the movement of the sun from sunrise to its present position. Slowly turn to the left, keeping the right arm horizontal, gradually raising the left arm until the left hand points to the sun again. Do not look at the sun.
4. Before noon
Mark the length of the shadow of the shadow stick. You can do this by using a stone or by marking the ground or tying a piece of string to the shadow stick and knotting it at then length of the shadow. Use to mark the length of the shadow every 15 minutes. The shadow is shortest at noon.
5. Before noon
Tell the children: When is the angle between their arms smallest? When are their arms together? [When pointing at sunrise.] What happened to their arms when you pointed to the path of the sun until noon? [The arms moved apart.] How will their arms be when pointing to the place where the sun sets? [Together.] Do you think their arms will keep moving apart from pointing at the sun now until the sun sets? [No.] When will their arms be farthest apart? [Noon or midday.] Show with their arms the complete movement of the sun, sunrise to noon to sunset. [Left arm moves through half a circle.] Tell them to draw the path of the sun with times, in their book.
Extra Activity
Path of the sun during the year: If you measure the shadow from the shadow stick at noon in different months, you will notice it is shorter in December or summer than in June or Winter. The sun is "higher " in the sky " in December. There is no difference at the equator, but greater difference as they move south or north of the equator. As you live in the Southern Hemisphere, the sun always appears to be in the northern sky and shadows always stretch away from the north.
4.43 Water from the air
See diagram 37.132: Water cycle | See diagram 37.133: Simulated rain cycle
1. Put ice cubes in a plastic bag, close the bag and hit it with a hammer to smash the ice cubes into small pieces of crushed ice.
2. Half fill a plastic cup with the crushed ice. Note anything that appears in the outside of the plastic cup to the same level as the level of crushed ice inside. It may be clear droplets or a white solid.
3. Add table salt to the crushed ice and stir it with a plastic spoon.
4. Note that more white solid appears on the outside of the plastic cup.
5. Use the plastic spoon to scrape some of the white substance off the outside of the plastic cup.
6. Hold the plastic spoon in the sunlight. The white substance melt to become a clear liquid. Taste the liquid. It is water.
7. If you cool air, drops of water form on the plastic cup called dew. If you cool air more, the drops of water freeze to form ice. We cannot see the water in the air because it is a gas called water vapour.