Year 4 lessons for primary schools.

School Science Lessons
2024-03-13

Primary Science Lessons, Year 4
(year 4
Contents
Suggested answers to the teacher's questions are shown within [square brackets].
4.16 Air resistance
4.11 Air temperature
4.01 Animal legs
4.02 Animal friends
4.25 Care for dogs
4.25A Care for pets
4.24 Catching the ruler
4.27 Children with diarrhoea
4.41 Cool water, melt ice
4.39.1 Cooling melted solids
4.18 Diameter of a thread
4.03 Fish parts
4.08 Flying kites
4.48 Freezing water expands
4.40 Heat water, cool water vapour
4.10 Heat, conductors and insulators
4.09 Heat from rubbing
4.44 Heated materials expand
4.07 How sound travels
4.47 "Human water"
4.45 Ice floats in water
4.13 Inertia tricks
4.38 Liquids in the sun
4.05 Lizards and snakes
4.33 Make sedimentary rocks
4.20 Measure chest expansion
4.39 Melt different solids
4.22 Memory games
4.49 Microwave ice
4.28 Mixing and dissolving
4.29 Mixing liquids with water
4.46 Pressure melts ice
4.35 Protect trees
4.14 Prepare crystals
4.19 Prepare invisible inks
4.30 Propellers
4.34 Protect soils
4.12 Smoke moves up and down
4.06 Snake bite
4.37 Soil watering bottle
4.21 Sun movement
4.42 Sundials
4.26 Temperature during the day
4.23 Test your reflexes
4.36 Water climbs up
4.36a Water climbs up soil
4.43 Water from the air
4.32 Weathering rocks

4.01 Animal legs
See diagram 9.300: Animals
Teach the children 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.
3. Funny Animals Game.
3.1 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.]
3.2 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.]

4.02 Animal friends
Teach the children 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.

4.03 Fish parts
See diagram 9.301: Parts of a fish
See diagram 9.302: Shark, bony fish
Examine a live fish, draw the fish and label the parts, 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.]
4. Start a classroom aquarium.

4.05 Lizards and snakes
Teach the children 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.
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.
5. Watch live lizards and snakes.
Look at them from above.
How do they move along the ground? [Lizards walk on legs, snakes slide on their bodies]

4.06 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.
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.
Around 81 000 to 138 000 people die each year, because of snake bites, and around three times as many
amputations and other permanent disabilities are caused by snakebites annually.
WHO released the executive summary for a global strategy to reduce by 50% the numbers of snakebite induced
deaths and disabilities by 2030.

4.07 How sound travels
See diagram 26.192: Bell from a spoon
See diagram 26.194: Stretched rubber band
See diagram 26.195: String telephone
Teach the children 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.]
5. 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?

4.08 Flying kites
Teach the children to make a kite and fly it.
Use 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:
3.1 Pull the string in quickly? [Kite moves steadily, starts to move up.]
3.2 Let the string out quickly? [Kite loops about, starts to move downwards.]
3.3 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.
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.]
Ask the children to show you with their arms the angle at which the kite is flying.
Let the kite rise and fall.
Ask the children to move their arms so that the angle between the string and the ground can be measured.
Commercial
Kite collection: Single line designs, Dual line stunt kites, Dual line parafoil kites

4.09 Heat from rubbing
Teach the children 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 your 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.]
4. Think of examples of rubbing things causing heat, e.g. tires on the road, making a fire with a bow.
When things are rubbed together they get hot. Rubbing things that feel rough get hotter than rubbing things that feel smooth.
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, conductors and insulators
See diagram 23.1.2: Heat different solids
Teach the children to show that heat moves faster through heat conductors and slower through heat 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.]
5. 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.

4.11 Air temperature
See diagram 23.7.03: Wall thermometer
1. Teach the children to observe the difference in temperature in different places.
Use a 0^oC to 100^oC thermometer and different places where differences in temperature can be seen.
Do not let children hold the bulb of the temperature in the sun.
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?
4. How does temperature in soil change during the day?
Does it change more, when deep in the soil or just under the surface?

Teach the children 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 100^oC 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	29^oC	30^oC	32^oC	32^oC	33^oC	35^oC	32^oC	31^oC

4. 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 23.2.8: Smoke moves up and down
See diagram 37.120: Convection currents
Teach the children 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? [No, ]
Can you 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?
6. Tell them about smoke going up and down near fires at home.
Smoke moves where the air moves.
Smoke goes up when the hotter air goes up.
Smoke goes down when the cooler air goes down.
Around a fire, the normal air is cooler, so it's heavier and presses down so that the lighter air containing smoke particles goes up.
The smoke floats up through the air just like a bubble floating upwards in water.

4.13 Inertia tricks
1. Inertia with a stone
See diagram: 6.240: Inertia with a stone
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: Inertia with two drink-can pendulums
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: Flick a card under a coin
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 habit
See diagram 3.2.49: Seed crystals in saturated solution
See diagram 3.2.50: Crystal crown
Teach the children to dissolve pure substances and make crystals.
Use 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.
Use 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.]

4.16 Air resistance
See diagram: 12.157: Air resistance
Air pressure umbrella
Teach the children to explain air resistance.
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.

4.18 Diameter of a thread
See diagram 2.1.9: Diameter of a thread
1. Teach the children to estimate the diameter of a thread.
Wind thread around a ruler to cover 2 cm of rules.
The number of winds = W, The diameter of the thread = 2/ W.2. 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
Teach the children to 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
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 9.242.2: Lungs
Teach the children 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.]
5 How often do they breathe in and out in a minute:
5.1 when sitting quietly,
5.2 after running?
Does the chest expansion change? [Yes, chest expansion is greater after running.]

4.21 Sun movement
Teach the children to describe the movement of the sun during the day.
Think about how to record the position of the rising and setting sun.
Can you arrange for someone to see the position of the rising and setting sun from the shadow stick in the school grounds?
Also, can the children see the position of the rising and setting sun from their homes?
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 see to the east and west for some distance.
Teach this lesson each side of midday.
Before the lesson, observe where the sun rises and sets from the shadow stick.
For example, the sun rises at 6.30 a.m. over the big Kapok tree and the sun sets at 6.35 p.m. over the coconut tree near the store.
You do not need to know compass directions.
Before the lesson, ask the children to notice where and when the sun rises and sets from their home.
At midday (noon) the sun is at its zenith, it is directly above you and is at an angle of 90^o to the horizon.
The shadow is nearly north to south.
Teach the class outside, between 11.00 a.m. and midday.
1. Where and when the sun rises and sets looking at it from your own house.
Take the children outside and shoe the children where the sun rises and sets looking from the shadow stick in the school.
2. Stand up straight and hold your arms out straight, palms down, hand palm touching the back of the hand.
Now tell the children to keep your right arm horizontal, raise the left arm until the left hand is pointing straight at the sun.
DO NOT LOOK AT THE SUN!
Can you see the angle between the two arms? [About 80^o]
3. Hold both arms horizontal again, left hand over right.
Point the arms at the place where the sun rises in the east.
Use your left hand to trace the movement of the sun from sunrise to its present position.
Turn slowly 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 undo this by using a stone or marking the ground or tying a piece of string to the shadow stick and knotting it at then length of
the shadow.
You will need to mark the length of the shadow every 15 minutes.
The shadow is shortest at noon.
5. Before noon.
Ask the children:
When is the angle between your arms smallest?
When are your arms together? [After pointing at sunrise]
What happened to your arms when you pointed to the path of the sun until noon? [Arms moved apart.]
How will your arms be when pointing to the place where the sun sets? [Together.]
Do you think your arms will keep moving apart from pointing at the sun now until the sun sets? [No.]
When will your arms be farthest apart? [Noon or midday.]
Show with your arms the complete movement of the sun, sunrise to noon to sunset. [Left arm moves through half a circle.]
Draw the path of the sun with times, in your book.
6. 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 you move south or north of the equator.
If you live in the Southern Hemisphere, the sun always appears to be in the northern sky and shadows always stretch away from the
north.

4.22 Memory games
Teach the children 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.
Groups of four children - two pairs of players.
2. 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.
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.
3. 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".

4.23 Test your reflexes
Teach the children 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.
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?
5. Are there any other reflexes?
Kick your toe. The reflex is to 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 Catching the ruler
See diagram 9.249: Reaction time
Teach the children to observe how fast they can react to a change.
Use 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.
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. Catching a bank note
Hold the top of a bank note in the left hand with the bank note hanging down.
Hold the fingers of the right hand level with the bottom of the bank note.
Open the left hand to drop the bank note and catch it with the right hand.
It is easy to catch.
Repeat the experiment by letting another person hold the bank note with the left hand.
When the other person opens the left hand to drop the bank note it is very difficult to catch.
5. 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.
6. 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.
7. 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 Care for dogs
See diagram 9.308: Parts of a dog
Teach the children 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.
5. Can you show how to train a dog to respond to simple commands such as "sit" and "come"?

4.25A Care for pets
by Jessica Brody
1. Bringing home a new pet is a big responsibility, similar to having a child.
You are now in charge of making them comfortable, feeding them, and keeping them safe.
It is a big job, but it can be truly rewarding.
Before your pet arrives
Before bringing your pet home, put any breakable or important possessions out of reach of your new pet.
Look around for places they could get stuck or furniture that could hurt them, and secure doors and windows to prevent your pet from
escaping.
Learn about foods that could be dangerous for your pet and keep them out of reach or use child safety latches on cabinets and pantries.
Do not forget to keep household cleaners, pesticides, and any other chemicals locked away from your pet.
Assume they will try to eat anything they get hold of.
Remember that dogs can be poisoned by chocolate!
Walk around your house, checking for poisonous plants and holes in gates or fences.
Scope out your neighbourhood to be aware of other animals that may roam around off-leash that you may want to avoid with your pet.
2. Bringing home your new pet
Once your pet arrives home, let them wander around the areas that are safe for them to adjust to their new surroundings.
Your home is completely different from where they were and they will need time to get comfortable.
Make some comfortable beds for them in a few different places so that they can choose where they would like to be at different times
during the day.
Many pets like to vary their sleeping arrangements depending on temperature or where you might be in the house.
Use cushions, blankets, or pet crates to give them a secure spot to use when they are tired or need some alone time.
Just like any other member of the family, it is important to spend time with your pet.
3. Carve out some time every day to hang out with your pet and play with them.
They need exercise and companionship as much as they need food and water.
Spending time with them will build trust and loyalty, and cut back on destructive behaviour.
Before leaving your pet in the house alone, make sure they have food, water, and toys.
This will help them feel satisfied and quell boredom while you are out.
If you will be gone for a longer period of time, try getting a pet sitter or using a daycare to care for your pet when you are away.
4. The health of your pet is very important.
A veterinarian can help you keep your pet happy and healthy.
Schedule regular appointments with a vet to ensure your pet is up to date on vaccinations, gets flea and tick or other needed
medications, and that any health issues are caught early.
As your pet ages, they will require more time and patience.
Elderly pets can have more health problems just like us.
They are more prone to arthritis, weakness, joint issues, kidney problems, and heart problems.
You may need to make some modifications in your home to accommodate these issues, such as raising pet food platforms so they
will not have to lean down as much or not making them climb stairs.
5. Your new pet will become a valued family member with your love and support.
Time and patience will help them forge a lasting bond with you and your family.

4.26 Temperature during the day
Teach the children 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, you will show the recurring pattern of temperature change each day.
Use a 0-100^oC thermometer fixed in the classroom in a cool 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.
Teach the whole class 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 children the place for the thermometer and recording sheet.
Explain how you will read the temperature every half hour during the day and record it on the recording sheet and graph sheet.
Let the children all read the temperature now, then give pairs of students the job of reading temperature at different times.
3. Show the children your temperature readings from the previous day.
Write the recording sheet on the chalk board.
Show the children how to draw a graph of the changes in temperature by joining the temperatures plotted on the graph.
Recording Sheet Date
Time 8 am 9 am 10 am 11 am 12 noon one pm two pm three pm
Temp 29 30 32 32.5 33 33.5 32 31
Now can you read the graph? [Temperature rises from 8 am to one pm then falls]
Explain how government offices read the temperatures every day to help describe the weather.
4. 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?
For example, heavy rainstorms cause temperatures to drop.

Temperature at different places
Teach the children to observe the difference in temperature in different places.
Use a 0-100^oC thermometer and go to different places where differences in temperature can be measured.
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.
Examples of useful places to measure temperature differences are different places in the classroom, include different distances from
the roof, the same place in difference classrooms, on teachers table, 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 your book.
2. Give each child a chance to read the thermometer in a different place and record in your book.
3. What differences you noticed, e.g. under different shades, in the soil, in the classroom, in water.
4. How does temperature in soil change during the day?
Does it change more, deep in the soil or just under the surface?

4.27 Children with diarrhoea
Teach the children to take care of younger children with diarrhoea by replacing water lost, because of dehydration.
In many countries, diarrhoea is the most common cause of death in small children, and is specially frequent in babies between six
months and two years.
It is more common and dangerous in children who are malnourished.
Bottle-fed babies have diarrhoea more often than breast-fed babies.
Diarrhoea can be prevented by: breast-feeding babies for as long as possible, good nutrition and cleanliness.
If you are a good teacher you can teach your children how to care for younger children with diarrhoea.
Use sugar, salt, water, spoons, cups.
How to give the drink, coconut water or Special Drink.
Start giving the drink as soon as diarrhoea begins.
A child should drink for each time a stool is passed.
If the child vomits up the drink, keep giving more.
A little of it will stay in the stomach.
Give it in sips every two or three minutes.
If the child does not want to drink, gently insist that the child does so.
Keep giving the drink every two or three minutes, day and night until the child urinates normally, every two or three hours.
Older children and your mother can take turns through the night.
Warning signs.
Take child with diarrhoea to the Health Centre if the child:
1. shows any signs of dehydration, cannot drink or will not drink,
2. makes no urine for six hours,
3. has diarrhoea too often so cannot drink one glass per stool,
4. has blood in the stool,
5. diarrhoea lasts more than two days.
Make special drink for groups of four children.
1. Diarrhoea means frequent watery stools.
Often children with diarrhoea also have vomiting and a swollen belly with cramps.
The stools smell different.
2. Children die of diarrhoea usually, because your bodies lose too much water.
his loss of water is called dehydration.
All living things contain a lot of water.
For example, if you bring two cut plants to school, and put one in water and the other not, you will see that one will wilt.
A baby with diarrhoea loses water like the wilted plant.
3. Signs of dehydration: little or no urine, which is dark yellow.

4.28 Mixing and dissolving
Teach the children to show that some things mix with water and dissolve in it.
Use sugar, salt, fertilizer, chalk powder and clean sand.
Also you will need cups, glass jars and clean sticks for stirring.
If you intend to allow the children to taste the water make sure the water is clean and suitable for drinking.
Groups of four children.
1. Give each group some sand, sugar, a stirring stick and a glass jar. Pour a little sand and sugar into the dry glass jar.
Can you see the sand and sugar in the jar? [Yes.]
Mix the dry sand and sugar with the stirring stick.
Can you still see the sand and the sugar? [Yes, but they are not easy to see.]
Add water and stir again.
Can you still see the sand? [Yes]
Can you still see the sugar? [No]
Where did the sugar go? [Into the water. The water dissolved the sugar.]
2. Give each group some salt and a cup of water.
Taste the dry salt.
Taste the water.
Put salt into the cup and stir it.
Can you see the salt? [No]
Let the children taste the salty water.
Where did the salt go? [Into the water.]
How do we know the salt is in the water? [We can taste it.
The water dissolved the salt.
3. Put some chalk dust into the water and stir it.
Can you still see the chalk? [Yes]
Is it in the water? [No, the water did not dissolve the chalk dust.]
4. What can be dissolved in water? [Salt and sugar]
What cannot be dissolved in water? [Sand and chalk]
5. Put a small amount of fertilizer in water and stir.
Will it dissolve with water? [Yes]
Add a lot more fertilizer to the water.
Will it all dissolve? [No]

4.29 Mixing liquids with water
Teach the children to demonstrate that some liquids will mix with water and some will not.
Use: 1. A large containers of water for rinsing jars and bottles.
2. A large container of soapy water for washing jars and bottles.
3. Different liquids, e.g. methylated spirits, duplicator fluid, kerosene, cooking oil, engine oil, coconut oil, iodine, ink, detergent, vinegar.
4. Jars or bottles 5. Glass tubes or ice cream sticks, for stirring.
6. Liquids that mix with water, e.g. methylated spirits, vinegar, cordial, detergents, iodine and ink.
Some liquids that do not mix with water are kerosene and oils.
1. Half fill the jar with water, put in a small amount of methylated spirits, stir and watch what happens to the mixture?
[The methylated spirits mixes with the water.
It spreads throughout the water.
It does not float on top or sink to the bottom of the water.]
Empty the jar, then wash it in the bucket containing soapy water.
Then rinse it in the bucket of clean water.
2. Repeat the experiment using kerosene instead of methylated spirits.
Does the kerosene mix with the water? [No]
What happens to the kerosene? [It floats on the top of the water.]
3. Repeat the experiment using each of the liquids in turn.
Do all the liquids mix with water? [No]
4. Name one liquid that mixes with water? [Cordial, ink, methylated spirits.]
5. Do insecticides and weedicides mix with water? [Yes, but they mix better if you add soap or detergent.]
6.

4.30 Propellers
See diagram 21.266: Propeller
Teach the children to make a propeller turn by running or blowing on it and that moving air causes the propeller to turn.
Use small pieces of cardboard or stiff paper, pins, pencils or sticks, coconut leaves or midribs, grass or mango leaves.
The hole must be a little larger than the pin and there must be a space between the propeller and the end of the pencil or stick to allow
the propeller to move freely.
A frangipani flower or a piece of coconut broom stick also makes a good propeller.
You can also carve a propeller out of soft wood. Push a long stick through the centre.
Put a stick in a bottle.
When you turn into the wind it sounds like an aeroplane.
1. Give out the materials and tell the children to push the pin through the centre of the piece of cardboard.
Make the hole a little larger than the pin. Now you can hold the pin between the thumb and forefinger and run with it.
2. Pin the propeller on to the blunt end of a pencil then hold the pencil and run with it or turn it into the wind.
3. What happens to the propeller? [It turns round.]
What made the propeller turn around? [Moving air]
How can we make the propeller turn faster? [You move faster or the wind becomes faster.]
How can we make the propeller stop? [We stop, or wind stops.]
If the air does not move how can we make the propeller move? [Blow on it.]
4. Aeroplane relay race
Line the children up in teams for a relay race.
The baton for each team is a propeller.
Which team wins the race?
Which propeller was turning the fastest? [The propeller held by the fastest child.]
If you have seen a propeller on a boat or a plane?
Was the boat or plane moving?
Was the water or air moving? [Yes, the propeller was making the water or air near the boat or plane move backwards.]
Have you seen other propellers? [Windmills, electric fans, car fans turned by a fan belt.]

4.32 Weathering rocks
See diagram 6.04: Weathering
Plant roots split rock
Teach the children 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
Teach the children 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.]
4. Collect sedimentary rocks from the local area.

4.34 Protect soils
See diagram: 6.62: Water on slopes
Protecting soils on slopes
Teach the children 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.
5. 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.

4.35 Protect trees
See diagram 9.53.9: Acacia
Teach the children to state why we should carefully protect your bush trees.
Use trees are part of out natural heritage.
We should make sure that all the different kinds of trees in your forests will be there in the future for the next generations.
Forest trees have survived for thousands of years so why should you worry about them now?
The population is increasing rapidly so there are now more people who want to use the products of the forest.
Trees can be cut down easily by modern equipment such as chain saws.
Logging of a forest has the result that all the largest trees are cut out.
They may grow again.
Cutting down a forest for wood chipping means that all trees are cut down and the same type of forest may never grow there again.
Burning off grass lands kills any small trees.
1. Explain the importance of the forest.
It is not just the bush.
It has been a source of benefit for the people for a long time.
Divide the class into groups.
Each group must list the benefits to the people of the forest.
Read out their list.
Summarize the benefits on the chalkboard.
2. List the names of bush trees that benefit people, e.g. cotton tree for stuffing pillows, Kamarere for timber, and fuel wood.
3. Why we should not burn grassland? [The small tree seedling cannot grow and so the forest shrinks.]
4. What can you do to tell other people to conserve your trees?
5. Talk from a forestry officer.
The teacher should have previously informed the officer ahead of time for this exercise.

4.36 Water climbs up
See diagram 6.36: Water climbs up
Teach the children to show that water can climb up some substances and that water climbs up different substances at different speeds.
Use strips of newspaper about 2. 5 cm wide and 30 cm long, pieces of thick string about 30 cm long, tin lids, sticky tape, box, ruler.
The string and paper should be thick, soft and absorbent.
If you do not have any suitable string, you use newspaper cut into thin strips.
Put a pin on the end of the paper strip to act as a weight.
Use a pencil to mark zero above the pin then draw a mark every centimetre.
The level of the water should be at the zero.
Before the lesson, set up the experiment and watch the water climbing up the paper and string for five minutes.
Draw the results on the chalkboard.
This lets us see practical aspects of capillarity both at home and among living things.
1. Use the sticky tape to stick the strip of paper and the string to the top of the box.
The string and paper must hang down so that they just touch the water.
2. Note the time when you put the string and paper in the water.
Watch the strips and string.
What happens? [The water climbs up the paper and string.]
After five minutes tell the children to measure the heights the water has climbed up the water and the string.
The heights are measured up from the surface of the water.
Write these heights in your table of results.
3. Repeat after five minutes.
Repeat up to 30 minutes.
Each child should have a chance of measuring.
4. Does the water climb up farther in the string or paper?
Check carefully that the children measure from the top surface of the water in the tin lid, at 0 on the rule, to the top of the wet mark.
5. Can you think of anything people use at home where the liquid climbs up a string? [Kerosene climbs up the wick in a kerosene lamp.]
Dip a long piece of white chalk into ink. Does the ink climb up? [Yes.]
Water can also climb up soil from damp places below to dry places above.
This helps plants to get water.

4.36a Water climbs up soil
Teach the children 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.
Groups of four.
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.]
5. Note that the time taken for water to reach the top of the tubing.
How fast can the water move in one hour?

4.37 Soil watering bottle
Teach the children 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
Teach the children to describe what happens when different liquids are left in the sun.
Use 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.]
3. 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: Simple stand for heating
Melting occurs when a substance is heated and it then changes from solid state to liquid state.
Use: candles or a spirit burner (alcohol lamp) or a fire.
List A: Margarine or butter or animal fat.
List B: Plasticine or wax, or ice, or candle.
List C: Salt or stones or nails or lead.
List D: Sugar or paper or feathers.
Also, you will need clothes pegs, or tongs or two sticks to hold things over the candle flame.
Teach the children to describe substances that can be melted with a candle flame.
1. Hard things are called solids.
Soft things that you can pour, are called liquids.
When some solid substances are heated, they change from solid to liquid.
You say that these substances melt.
2. Give out substances from each list.
Heat each substance and notice whether you melt.
3. Do these substances melt:
List A? [Yes.]
List B? [Yes.]
List C? [No.]
List D? [No, these things become black and catch fire.]
After a few minutes, ask the children if the substances are still melted. [No, they can become solid again.]
4. List C substances can be melted if they are heated to a very high temperature, e.g. making lead sinkers.
5. Can you think of something that is liquid, but gets hard when you heat it? [An egg, first the yolk then the white turns from liquid to
solid, but later it burns, as in List D.

4.39.1 Cooling melted solids
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.
Teach the children to describe what happens when different solids are heated.
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 may become 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.
What happens in each case and make two lists on the chalkboard?
3. Note what happened when the melted solids were left to cool.
Some solids melted to form liquids, e.g. ice, candle wax, margarine.
Some solids that did not melt: ice, stone, rubber, common salt, clay
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.
4. List all solids and liquids at home.

4.40 Heat water, cool water vapour
Teach the children to describe what happens when liquids are heated to boiling then cooled.
Use 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.
6. 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.]

4.41 Cool water, melt ice
Teach the children to cool water and melt ice.
Put an empty jar or beaker on each table.
Only the teacher touches or handles the thermometers!
The melting point or freezing point of ice / water is at zero degrees Celsius, 0^oC.
Draw temperature scale near 0^oC on chalkboard
1. Place a thermometer in each empty jar.
Ask children to read the air temperature in degrees Celsius, ^oC, e.g. 20^oC.
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 0^oC. then stops.

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 0^oC.
A mixture of salt and ice is called a freezing mixture.

4.42 Sundials
See diagram 36.68: Shadow stick sundial
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^o to the horizon.
The shadow is nearly north to south, outside between 11: 00 a.m. and Noon.

Teach the children to describe the movement of the sun during the day.
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^o.]

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.

6. 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.
If 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
Teach the children to show how water is in the air.
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.
Half fill a plastic cup with the crushed ice.
Note anything that appears in the outside of the plastic cup is the same level as the level of crushed ice inside it.
Clear droplets or a white solid may appear on the plastic cup.
2. Add table salt to the crushed ice and stir it with a plastic spoon.
More white solid appears on the outside of the plastic cup.
3. Use a plastic spoon to scrape some of the white substance off the outside of the plastic cup.
Hold the plastic spoon in the sunlight.
The white substance melt to become a clear liquid.
Taste the liquid.
It is water.
4. 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.

4.44 Heated materials expand
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.

4.45 Ice floats in water
1. Show an ice cube floating in fresh water.
Do heavy things or light things float in water? [Light things.]
2. Put cold water into a measuring cylinder and record the volume of water, V1
Drop ice cubes onto the water then push them down with the blunt end of a pencil, until the top ice cube is just under the water.
Record the volume of the water with ice in it, V2.
Calculate the volume of the ice, V2-V1
Put the same number of ice cubes in a plastic cup, Cup 1.
Put the V1 volume of water in an identical plastic cup, Cup 2.
Put the two cups on a beam balance.
The weight of Cup 2 is greater than the weight of Cup 1
The volume of ice is lighter than the same volume of water.
3. 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 or arctic ocean? [Icebergs.]
Where do the icebergs come from? [Glaciers, 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 freeze to form sea ice at about -1.8^o.]
Show ice cubes floating higher in salt water than in fresh water.

4.46 Pressure melts ice
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.
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.
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. 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 at another person, because this snowball is solid
ice!
The ice in a glacier comes from snow squeezed together by its own weight.

4.47 "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.
At room temperature, the waters turn round and round, turning close together.
As the temperature drops they turn more slowly.
At 0^oC. 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

4.48 Freezing water expands
You can do this experiment at home.
Fill an ice cube tray exactly with water to make separate ice cubes.
Put the ice cube tray 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.
Take out some of the ice cubes and put them in water.
The ice cubes can float in water.
So when water changes to ice, it expands

4.49 Microwave ice
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.