Natural Sciences and Technology - Grade 4 - Term 2

Topic 6 – Materials around us

Unit 1 – Solids, liquids and gases 14 April – 15 April 2020

Matter makes up all the materials and substances that exist on Earth.

Everything around us is matter (Everything around us is either a solid, a liquid or

a gas)

Matter/ materials can exist in three different forms – solids, liquids and gases

We call these three forms the states of matter

Properties of the three states of matter:

o Solids

Has a fixed shape

You cannot change the shape easily, you will need some force to

change the shape

E.g. If you hit a brick with a hammer, its shape will change

o Liquids

Does not have a fixed shape

A liquid will take the shape of the container you pour it in, it flows

E.g. If you pour milk into a glass, it takes the shape of the glass.

When you pour it into a bowl, it will take the shape of the bowl

o Gases

Has no shape but it takes up space

A gas moves around freely and spreads out into open spaces.

You cannot keep it in an open container, the container must be

closed

You cannot see, feel or smell some gases

E.g. Air is made up of different gases. If you blow up a balloon and

tie it off, the gas (air) is trapped inside. But when you untie the

balloon, the gas escapes and the balloon shrinks again.

Unit 2 – Change of State 16 April – 17 April 2020

A substance changes from one state of matter to another when it gains or loses

heat

A thermometer is used to measure temperature (how hot or cold something is)

o Temperature is measured in degrees Celsius (°C)

o Water freezes at 0 °C

o Water boils at 100 °C

Melting

o Changing from a solid to a liquid by adding heat

o E.g. If ice cream gets warm and melts

Evaporating

o Changing from a liquid to gas by adding heat

o E.g. When you boil water in a kettle steam (gas/water vapour) is released

Condensing

o Changing from gas to liquid by cooling it down

o Gases condense when they lose heat

o E.g. When you boil water in a kettle, hold a plate above it. The steam will

collect on the cold plate and change back into water

Solidifying

o Changing from liquid to solid by cooling it down

o E.g. If you put water in the freezer it will change into ice

Unit 3 – The water cycle 20 April – 22 April 2020

The Earth has a limited amount of water

The movement of water from the land and sea, to the air and back again

Water will change its state through evaporation, condensation, melting and

freezing

o Water on the Earth’s surface evaporates and moves up into the air as

water vapour

Water from the sea, rivers, dams is heated by the sun, and

changes into gas

o The water vapour cools and condenses as it rises into the air

The gas collects in the sky because it cools down

o Drops of water high in the air form clouds

The more water that collects, the darker the clouds become

o Drops of water will fall to the Earth as rain

Water in the clouds can freeze and will fall to the Earth as snow or

hail. It will melt when it touches the warm surface of the Earth

o Rain, snow and hail bring water back to the Earth’s surface

Topic 6 – Activity 23 April – 27 April 2020

1. Use the words to complete the sentences.

states solids cool solidify shape space melt condense evaporate

a. The ________________________ of substances are solid, liquid and gas.

b. __________________ keep their shape.

c. Liquids take the ________________ of the container they are in.

d. Gases have no __________________, but they take up

__________________.

e. When we heat solids, they ______________ and become liquid.

f. When liquids are heated they _______________ to form gases.

g. When gases ________________ they ________________ to form liquids.

h. When liquids cool, they _____________________ and become solid.

2. Identify the states of matter (materials) in each of the pictures.

__________________ _________________

__________________ _____________________

__________________

3. Which changes listed below are examples of melting and which are examples of

solidifying? Give a reason for each answer.

a. You have a piece of chocolate in your pocket on a hot day.

b. You put jelly in the fridge to set.

c. You put butter in a pan so that you can fry an egg.

4. Identify the change of state in the following parts of the water cycle:

a. Clouds form __________________

b. Snow forms __________________

c. Water vapour forms __________________

d. Snow becomes liquid water __________________

Topic 7 – Solid Materials

Unit 1 – Raw and Manufactured Materials 28 April – 30 April 2020

Raw materials are natural material such as wood, sand and clay that can be

used to make things

Natural materials come from nature

Sometimes we can use raw materials as they are

When people change raw materials to make something else, we call it

manufactured materials

Raw materials that are used to make other materials:

o Sand is used to make glass

Rocks are broken down by the wind and water to become sand

Sand is heated and melted into liquid

The liquid can be shaped into different objects

When it cools down, it solidifies to become glass objects

o Clay is used to make ceramics

Clay is made from very fine wet sand

It can be shaped into different objects

The objects are heated in ovens to become hard

These ceramic objects are hard but brittle (it can break easily)

o Coal and oil are used to make plastics, paints and fabrics

Coal is a hard black substance that comes from deep underground

Oil is a dark liquid that is found deep underground

Through different processes coal and oil is used to make plastic

objects, fibres such as yarn or fabric or paint.

o Animal wool and hides are used to make fabrics and leather

Sheep’s’ wool is spun into yarn. The yarn is woven or knit into

fabrics

Animal hides are changed into flexible soft leather to make shoes,

handbags, etc.

o Wood and fibre from plants are used to make paper

Wood chips are cooked to a pulp. It goes through rollers that

remove the water and dries the pulp out. Then the paper is cut into

different sizes

Unit 2 – Properties of materials 4 May – 5 May 2020

We make things out of different materials, that is why we need to know what the

properties of the materials are – what each materials looks like and how it

behaves

E.g. if you need a container to store water, the material that the container is

made from must be:

o waterproof so that it doesn’t leak

o strong enough to hold the water

o light enough to carry around

Properties of materials

o Hard or soft

If you cannot scratch or dent a material, it is hard

E.g. you can scratch a candle with your fingernail, so it is soft

E.g. you cannot make a dent in a piece of wood, so it is hard

o Stiff or flexible

Flexible materials bend easily without breaking, e.g. a hosepipe

Stiff material doesn’t bend easily, e.g. a plastic ruler

o Strong or weak

Helps us to see if it is the right material to use

E.g. a stone is very strong, but it is very heavy to build

o Light or heavy

Helps us to see if it is the right material to use

E.g. Plastic is light but can also be very strong

o Waterproof or absorbent

Many fabrics are absorbent and can take in liquids, e.g. a

washcloth

Other materials don’t allow liquids to pass through, e.g. a raincoat

Topic 7 – Activity 6 May – 8 May 2020

1. Match each word in column A with the correct description in column B.

A B

1. Plastics a. Threads in plant and animal materials

2. Absorbent b. Made of clay and sand

3. Brittle c. Made from oil and coal

4. Fibres d. Breaks easily

5. Ceramics e. Soak up a liquid easily

1._____ 4._____

2._____ 5._____

3._____

2. Describe the raw material of each of the following:

a. Ceramics

b. Leather

3. Write a sentence to describe what glass is.

4. Tick the properties of glass, clay and plastic.

Properties Glass Clay Plastic

Flexible

Brittle

Becomes hard when baked

Waterproof

Soft

5. Use the words in the word box to answer the questions below.

Wool slippers Wooden walking

stick Polyester pillow Glass jug

Floor tile Knitting wool Plastic shopping

bag

Plastic knitting

needles

a. Name one object that is made of a hard material.

b. Give two examples of objects that are made of soft materials

c. List two objects that are made of stiff materials

d. List two objects that are made of flexible materials.

Topic 8 – Strengthening Materials

Unit 1 – Ways to Strengthen Materials 12 May – 15 May 2020

Structures like buildings must be strong enough to stand firm against powerful

winds, hail and rainstorms

The materials used must also be strong

There are different methods/ ways to make materials stronger to build structures.

Methods to strengthen materials:

o Strengthen by folding

Bending a material over on itself can make it stronger

E.g. cardboard boxes have a folded layer in the middle that makes

it stiff, harder and stronger to carry heavier things in.

o Strengthen with hollow pillars

We can save materials by using strong, hollow pillars to hold roofs

up

o Strengthen materials with struts

Struts are lengths of strong materials that are joined to make a

strong frame.

E.g. roll paper into thin tubes to make a chair with.

A fair test

o When we investigate things, we need to test them

o A test is fair when we test everything in the same way

o A fair test has two parts – control and experiment

Control – the materials have not been changed in any way

Experiment – one thing about the experiment is changed at a time

to see how the materials will act

o An example of a fair test:

Test the strength of a folded paper

Method:

Use two sheets of paper (one folded zig-zag, the other flat),

four empty boxes of the same size (e.g. jelly boxes),

two pencils (same length),

a ruler

Conduct the test:

o Put the boxes exactly the same distance apart from

each other

o Put the folded sheet over two boxes, and the flat

sheet over the other two boxes

o Put the pencils in the middle of each sheet

Results:

o Which sheet could hold the pencil? Which sheet was

stronger?

Conclusion/ Interpretation:

o What does the results of the fair test prove?

Topic 8 – Practical Task 18 May – 22 May 2020

Test and compare the strength of hollow pillars

Watch the video of the fair test being carried out or try it at home

https://www.youtube.com/watch?v=9Bhl8HkmCzo

o Use three paper pillars

Square – fold a paper into four equal parts, stick the edges with

cellotape to make a square shape

Circular – bring the sides of the paper together and tape the sides

together

Triangular – fold a paper into three equal parts, tape the sides

together

o Use books or other flat items of the same size to put on each of the pillars,

one at a time until the pillar collapses.

o Count how many items each pillar could support

o Write down the results and conclusion

Results from the video:

Square pillar Triangular pillar Circular pillar

Number of items

supported by

pillar

14 4 18

A bar graph is a picture that shows information in bars or columns

Conclusion (Interpret the results):

o The circular pillar is the strongest because it could hold the most books.

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2

4

6

8

10

12

14

16

18

20

Square pillar Triangular pillar Circular pillar

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Topic 8 – Activity 25 May – 27 May 2020

1. Match each word in column A with the correct description in column B.

A B

1. Square hollow pillar

a. Bending something over on itself to strengthen a

sheet of material

2. Folding

b. A length of material that we insert into a frame

structure to strengthen it

3. Triangular hollow pillar

c. When a flat sheet of material is folded into a

square pillar

4. Struts

d. When a flat sheet of material is folded into a

triangular pillar

5. Factors e. Explain what a result means

6. Control f. A test where one factor at a time is changed

7. Interpret g. Object or material where nothing is changed

8. Fair test

h. A diagram or picture that shows information in

bars or columns

9. Experiment i. Things that play a role in the result

10. Bar graph

j. A special way of doing an experiment with results

that can be trusted

1._____ 6._____

2._____ 7._____

3._____ 8._____

4._____ 9._____

5._____ 10.____

2. Name a structure from daily life that is a circular pillar.

3. Why does it have a circular shape?

4. Name a structure from daily life that is a square pillar.

5. Complete the sentence: the roof of a rectangular house is an overturned

__________________ pillar.

6. How many things at a time can you change in a fair test?

7. Why must all the other factors be the same in a fair test?

Topic 9 – Strong Frame Structures

Unit 1 – Struts and Frame Structures 28 May – 29 May 2020

Frame structures :

o Need to be very strong

o Functions of frame structures:

To hold things up

To give a certain shape

To bridge a gap between two places

o Made out of different parts or struts joined together

Struts:

o Can be joined into triangular shapes to make a strong, stable frame

o Struts are added to unstable square shapes to form stable triangles

o Triangular struts prevent the sides of a structure from splitting open at a

corner joint

o The struts also prevent two sides of a structure from moving closer

together at the corner joints

o Triangulation – To put triangles in a structure

o E.g. roof trusses, bridges, cranes, pylons and skeletons

Struts in the human skeleton:

o The bones in our legs and arms are struts and give shape to our bodies.

o Limb bones have joints that allow us to bend and move

Unit 2 – Indigenous Structures 1 June – 3 June 2020

People build different types of traditional houses from raw materials

They would use materials found in their environment (area where they live) –

Indigenous materials

E.g. An igloo made by the Inuit people from Alaska

Examples of shapes of housing structures in different parts of the world:

o Beehive structures – Huts made by Zulu, Swazi and Nama people

o Cylinder or circular shape covered with a cone-shaped roof – Rondavels

made by Xhosa people

o Triangular shape standing on the ground

o A cone-shaped structure standing on the ground – Teepee tents made by

American Red Indians

o A square house with a cone-shaped roof

Examples of making frameworks out of struts:

o House walls were made from wattle and daub

o Wattle – wooden twigs or strips that are woven into lattice

o The lattices are tied to the square framework and struts

o Daub – a sticky mixture of wet soil, clay, sand, animal dung and straw

o Wattle and daub have been used in structures found in Swazi

communities

Examples of indigenous houses of South Africa

o Rondavel

Huts have round walls and thatched roofs

Poles/ pillars are stuck into the ground

Planks/ struts are attached to the poles

The structure is covered with a mixture of clay and cattle dung

Roofs are made of wooden poles covered with thatch and sewn to

the poles. The roof is waterproof

o Beehive-shaped huts

An arch framework is made from flexible young trees

Branches are tied together to form triangles

Ropes and mats are woven from grass and laid over the frame. The

mats are tied to the frame

o Matjieshuis

Branches from tamarisk trees are cut and held over a hot fire to

bend, and left to cool

The bent branches are tied together in a dome/ arch shape

More branches are used as struts

Reeds are cut and dried out to weave mats. The mats are tied to

the frame

Topic 9 – Activity 4 June – 5 June 2020

1. Look at the pictures. Provide labels for A, B and C. Use the words ‘struts’,

‘pillars’, and ‘triangulation’.

2. Indigenous people used materials in their environment to build their houses.

Complete the table below.

People Materials used to build

houses

Houses they built

Inuit people from

Alaska

Ice blocks

Zulu people Young trees and grass mats

Nama people from

Namibia

Matjieshuis

Xhosa people Poles, stone, thatch

3. Explain what is meant by wattle and daub.

4. Explain what is meant by triangulation.

5. Give two examples of where triangulation is used in modern buildings or

structures.

Term 2 – Revision Activity 8 June – 12 June 2020

1. Jane covered a beaker of water with plastic wrap and left it in a sunny place.

When she came back an hour later she noticed droplets of liquid on the inside of

the plastic wrap.

Answer these questions:

a. What were the droplets made of?

b. Name the process by which the droplets formed.

c. If Jane measured the volume of water in the beaker after one hour, would it

be greater (more than), the same or less than when she started the

investigation? Explain your answer.

2. A group of learners made ice cream. They mixed together milk, sugar and cocoa

powder. They poured the mixture into a plastic container and put it in the freezer.

The learners took the container out of the freezer the next day.

a. Which state of matter was the milk when the learners began?

b. Which state of matter was the milk when they took the ice cream out of the

freezer?

c. Why did the milk change from one state to the other?

d. Name the process that took place to make the milk change state.

e. Why would the learners pour the ice cream mixture into the container before

they put it in the freezer?

3. Look at the words from the word box to answer the questions below.

Glass jug Dish cloth Gum boots Toothbrush Clay pot

Clay brick newspaper Plastic plate Leather belt towel

a. Name two objects that are flexible.

b. Name one object that is waterproof.

c. Name two objects that are absorbent.

d. List the objects that are brittle.

4. State why you would say an object is made of a soft material?

5. Name two ways in which a sheet of paper can be changed into strong hollow

pillars.

6. Which raw material is used to make a glass jug?

7. Give an example of a manufactured ceramic material.

8. Explain how a soft clay brick becomes hard.

9. Compare the properties of a glass jug and a plastic jug.

Glass Jug Plastic Jug

10. Describe what a fabric is, and give one example of a fabric.

11. Make a drawing with labels to show why a triangle is a more stable structure than

a square.

12. Explain how you can test which shape structure is stronger.