Processed materials

What are raw materials, natural materials and processed materials?
Which traditional processing methods have humans been using to give materials more desirable properties?

Introducing the unit

This unit provides an opportunity for learners to think of materials in terms of the distinctions between raw and processed materials. It is also an opportunity to link to Indigenous Knowledge when dealing with traditional methods of processing materials, and to draw learners attention to the fact that many of these traditional methods of processing are still used today. They are mostly supportive of sustainable living practices, and are becoming very trendy as a result. The introduction to this unit links it to the units that have preceded it.

Properties and uses

We call materials that have not yet been processed raw materials. Raw materials are made into other things. When raw materials are in the form in which they are found in nature, we can call them natural materials. A natural material is any material that comes from plants, animals, or the ground.

We have learnt that there are many different ways in which materials can be processed to give them new properties. After processing they may look, smell, feel or taste different. They will probably also be used for a totally different purpose from before.

Processed materials are materials which have been refined or built by humans from raw materials. Some examples include paper, steel and glass.

Raw or processed material?

Teacher's note: In this activity the learners must study a list of materials and then decide which represent raw materials and which represent processed materials. It is recommended that this should be a small group activity, since discussion and joint decision making is required.

INSTRUCTIONS:

Below is a list of different materials.
In your group, you need to sort the materials into two categories: Raw materials and Processed materials.
In your group, discuss all the materials listed before deciding in which category each one belongs.

Bread	Minerals from a mine	Sausage
Rice	Metal furniture	Wheat
Maize meal	Wooden furniture	Animal skin
Toothpaste	Leather shoes	Honey
Vegetables	Petrol	Crude oil
Meat	Necklace made of shells	Mealies
Wood	Metal from a mine	Vegetable soup

All the materials in the list above have been placed into a table (below). Discuss each material in your group and decide how to classify it. Is it a raw material or a processed material? Does it come from plants, animals or the ground? You can look at the table to guide you.

Categories of materials:

Material	Is type of material is it? (raw or processed)	What is the origin of the material? (plant, animal or Earth)
Bread	Processed	Plant
Rice	Raw	Plant
Maize meal	Processed	Plant
Toothpaste	Processed	Earth (Minerals)
Vegetables	Raw	Plant
Meat	Raw	Animal
Wood	Raw	Plant
Honey	Raw	Animal
Sausage	Processed	Animal
Metal furniture	Processed	Earth
Wooden furniture	Processed	Plant
Leather shoes	Processed	Animal
Petrol	Processed	Earth
Necklace made of shells	Processed	Animal
Minerals from a mine	Raw	Earth
Crude oil	Raw	Earth
Mealies	Raw	Plant
Wheat	Raw	Plant
Animal skin	Raw	Animal
Vegetable soup	Raw	Plant
Metal from a mine	Raw	Earth

QUESTIONS:

Draw a new table in which you place each processed material next to the Raw material that it may have been made from. For instance, in the table below, bread and wheat have been placed next to each other, because bread can be made from wheat.
In your table, try to match up as many Raw materials with Processed materials as you can.
Which of the materials do not match any other materials? Can you think of a match for each one that does not have a match?

'Necklace made of shells', 'vegetable soup' and 'rice' do not have matches. Use your discretion in evaluating learners' answers; some possibilities have been suggested in the table.

Processed Material	Raw Material
Bread	Wheat
Maize meal	Mielies
Toothpaste	Minerals from a mine
Sausage	Meat
Metal furniture	Metal from a mine
Wooden furniture	Wood
Leather shoes	Animal skin
Petrol	Crude oil
Necklace made of shells	Sea shells
Vegetable soup	Vegetables
Rice porridge / rice cakes / 'Rice Crispies'	Rice

Materials that have been processed are very useful to us because they have special properties. We already know that processed materials can be strong and durable. But what other properties do they have? Let's look at some example.

What do you put on when it is raining outside? Some processed materials are useful to use because they are waterproof. A rain jacket is made of a material which is waterproof, and so is an umbrella. Maybe you might wear gum boots or wellingtons? These shoes are very waterproof and made from specially processed plastic and rubber.

This man is wearing a rain jacket and has an umbrella made from waterproof materials.

These pink gumboots are very waterproof!

Paint is a processed material. The pigments used to make paint are natural materials, but the final product is a processed material.

Do you remember we mentioned pigments last term in Life and Living? What was the green pigment used in photosynthesis to make food for plants?

Chlorophyll

What special properties of paint make it useful to us?

Paint is in a liquid form so it can be easily painted on a surface. Paint also has colour so it can be used decoratively.

Think of all the cases where people use paint and write them down.

We paint the walls in our houses, we paint the outside walls of buildings, we paint roofs, we paint fences (especially iron fences to stop them from rusting), artists use paint to make paintings, people use paint to make signs which are informative, we paint road signs on the road to tell cars where to go.

We have just seen that processed materials can be used because they have special properties (such as paint having the ability to change an object's colour). In the last chapter we looked at concrete. We learned how to make concrete by combining different materials. But concrete can also be used decoratively as it has many different textures. Look at the pictures below which give some idea of the different textures of concrete and how it is used to make surfaces look interesting!

A fun activity here would be to take learners on a walk around school to see how many different textures you can identify on the buildings, paths, pavements, etc. They can make rubbings using pieces of paper and pencils or wax crayons.

Wow, I always thought concrete was so boring! Farrah would love this!

That is right Tom! And there are so many more properties that we could discuss, such as being fire resistant! But the best would be for you to go out and experience it for yourself and look at the materials around you with new eyes!

Investigating processed materials in the world around us

This can be used as a possible project where learners have to present their findings either in the form of a poster, a pamphlet or an oral to the class. Encourage learners to experiment with drawing, and even making rubbings of different textures. You can use some time in class for learners to walk around the school and classroom to investigate the materials used, and some part of the project can be set as homework to look at the processed materials in their homes and communities. This activity could also be combined with their other subjects like Art (use the rubbings to create an artwork) or Language (oral presentation).

INSTRUCTIONS:

Your task is to find examples of processed materials in the world around you, particularly non-metals.
You must look at why that material has been used and how its properties make it useful to us.
You must select two different locations to look for materials. One location can be the school or classroom, and another location could be your home or your community.
In Chapter 2, you did an activity looking at the uses of metals, but now you must focus on the uses of non-metals which are processed materials. Wood, for example does not fall into this category. It is a non-metal but it has not been processed.
Ask your teacher how you must present your findings. You could present it as a poster, or using a flipfile.
Include some pictures of the materials or drawings. You could even make rubbings of the different textures!
Try to find at least 4 different processed materials in each location. The materials must be used for different purposes and have different properties.

In the next section we will learn about some of the ways in which people processed materials in early times. Some of these traditional methods of processing materials are still used today!

Traditional processing

This section is quite reading-intensive. There are two rather long stories about the Khoikhoi youngster, Heitsi, that describe various methods of traditional processing. The stories have been written in such a way that they are factually correct, and so they may link well with other learning areas such as Life Orientation or Social Studies.

One idea would be to use these stories as comprehension pieces. Depending on the reading level of your learners you may choose to read it to them, or let the learners each read a paragraph in turn. (It is a requirement of CAPS that 'learners should read, write, draw and do practical tasks regularly'.) Another idea may be to allow learners to act out the two stories about Heitsi and his family.

An important cultural message to bring across is the resourcefulness of our ancestors, and how they used what was available to make their lives more comfortable.

People have been processing materials from the earliest times. In the old days only natural materials were available and people found many clever ways to make these materials more useful.

The first people who lived in our land had ways to harden wood and bone for making tools and hunting weapons. They also had ways of reinforcing the mud used for making traditional huts. They knew which materials made the best clothes and blankets, and which grass made the softest beds. They also knew exactly which reeds would make the best mats to cover their walls, and how to build houses best suited for their climate and lifestyle.

Some of these traditional ways of processing materials are still used today. In this section we will learn more about them.

Traditional materials and processing

Before South Africa was a country, several interesting groups of people lived in our land. The Khoikhoi people were one of the first nations to live in Southern Africa and many modern day South-Africans are descendants of the Khoikhoi. The Khoikhoi were pastoral people who kept goats, but also hunted animals for their meat and skins.

INSTRUCTIONS:

The following story tells us about the young Khoikhoi hunter, Heitsi, who prepares to go on an expedition to hunt a springbok.
Read the story carefully, and look out for clues about the ways in which Heitsi's people used and processed materials.
When you have read the story, answer the questions that follow.

Heitsi prepares for the hunt

Heitsi is getting his hunting kit ready for the hunt. He is not a man yet, but already a good hunter. When he was born, 11 summers ago, his mother named him after Heitsi-eibib, who was a mythical hunter, sorcerer and warrior in the stories of his people. His father and uncles have taught him how to use the traditional hunting weapons of the Khoikhoi: the bow and arrow and the "kierie" (throwing stick).

Heitsi is very excited about the hunt. Today he is hoping to kill a springbok, because he wants to cut a head dress for himself from the skin of the springbok. He can already imagine how envious his friends will be when he wears it proudly around his head.

He will give the rest of the springbok skin to his mother to turn into a blanket (karos) or a piece of clothing for his new baby sister. His mother will scrape the skin with a sharp stone or metal blade to remove the hair and rub it with animal fat for a long time to make it soft.

Heitsi slings the quiver in which he keeps his arrows over his shoulder. The quiver is made from tree bark. It is a good quiver, but he really wants one made of animal skin like the one his father carries. The arrows inside the quiver have wooden shafts and sharp tips made of metal. His younger cousins have arrows with tips made of hardwood. In the old days all the arrow tips were made of wood or bone, but Heitsi's people have been making contact with other peoples who have introduced them to metal.

He also keeps some tinder in his quiver. Tinder is the name for the soft, dry plant materials his people use when starting a fire. Another item he keeps in the quiver is a hollow reed that can be used like a straw to suck up water that has collected on the leaves of plants.

He knows that he has to handle the arrow tips very carefully because they are very sharp. He keeps them sharp by rubbing them on a special stone.

Another reason why Heitsi handles the arrows very carefully is because their tips have been covered with a layer of poison. His cousins sometimes use the sap from poisonous plants to treat their arrow tips, but he prefers to use snake poison because it is more potent.

He picks up his bow, and admires it for a moment. He made it himself from the flexible wood of a wild olive tree. The bow string is made from the gut of a small wild cat that he hunted last summer. His uncle's bow has a string made of twisted palm leaves, and it makes a beautiful sound when Uncle holds the end of the bow in his mouth and taps against the string with a stick. Tonight, when they return from the hunt, the men will dance around the fire while the women sing and clap their hands. There will be stories told about the hunt, and Heitsi will honour the soul of the springbok that he has killed.

The last weapon he picks up is his kierie. It has a long handle and a knob at the top end. The kierie was a gift from his favourite uncle. Uncle made it himself from strong wood. To make the kierie even stronger, Uncle placed it close to the fire for a long time. The heat from the fire dried out the wood and made it tough and strong.

At last Heitsi is ready for the hunt...

QUESTIONS:

In the story, many different traditional materials used by the Khoikhoi people are mentioned. In the table below, you must fill in what material was used for each purpose in the middle column. In the column on the right you must fill in what other material could be used for the same purpose.

Purpose	What material was used?	What other material could be used?
Making a quiver for arrows	Tree bark	Animal skin
Making the arrow shaft	Wood	(No alternative mentioned)
Making the arrow tip	Hardwood	Bone or metal
Making poison for the arrow tip	Poisonous plants	Snake poison
Making a bow	Olive wood	Any other flexible wood
Making a string for the bow	Animal gut	Twisted palm leaves
Making a blade for scraping the hair off animal skins.	Bone	Wood or metal

What processing method was used to turn animal skin into soft leather?

The skin was scraped with a blade to remove the hair and rubbed with animal fat.

What processing method was used to make wood harder so that it could be used to make an arrow tip or kierie?

The wood was hardened in the fire.

What processing method was used to make bone harder so that it could be used to make arrow tips?

The wood was hardened in the fire.

How did Heitsi keep his arrow tips sharp?

Heitsi rubbed the tips against a special stone to sharpen them.

Later, we will read about the traditional Khoikhoi house that Heitsi and his family lived in. First, we will learn about a different kind of traditional home, that is still seen today.

Some of the traditional homes in Africa are made of clay or mud. In the activity Making Bricks, we saw that mud (a mixture of soil and water) is not a very strong material. When it is dry, it can crumble and collapse. When it is reinforced, it can make a strong and durable building material that can be used to build a house. If it is built well, the house will last for many years.

Making a mud house stronger

In this activity learners are required to watch internet video clips. In the case that internet access is not available, pictures have been included for learners to look at instead.

In this activity we are going to look at some videos and pictures for ideas on how to process mud into a strong and durable building material. If you are not able to watch the videos, then look at the pictures.Many of these traditional building methods have become very popular amongst modern-day people who want to live in a sustainable way.

INSTRUCTIONS AND QUESTIONS:

Follow the link to the first video http://www.youtube.com/watch?v=-NlhtLDR-3s&feature=related. Watch the video and then answer the questions. Alternately, you could study the picture of the boy learning how to build a mud wall below.

The wall of a mud house with a stick frame.

What material is the house in the video and in the pictures made of?

Mud, sticks and cement

The man in the video used two methods to strengthen the walls of his house. What are they? Or else, look at the second picture above of a close up photo of a wall to see how they strengthened the wall.

He added cement to the mud, and he used sticks to build a framework for the house.

Follow the link to the second video http://www.youtube.com/watch?v=XNfArvnLxO0. Watch the video and then answer the questions or look at the pictures below.

A close up photograph of a mud used to make the wall.

What materials are recommended to reinforce the mud?

Dry grass and stones.

Why do you think the wall should be built thicker at the bottom than at the top?

The wall will be more stable when it is built thicker at the bottom. It will not fall over easily.

Write a step-wise procedure for building a mud shelter.

Teacher note: In the video, the steps are laid out quite clearly. But you do not need the video to write the steps. For example the steps could include to first put sticks into the ground to mark out where the walls of the house would be, then to collect or make the mud, and to add grass and stones to reinforce it. Then pack the mud up against the sticks as the you boy is doing in the first picture. Then to leave the mud to dry.

Follow the link to the third video that shows how to build a mud wall http://youtu.be/lS1vmfIRkkg. Alternatively you could look carefully at the pictures below.

The mixture of clay and straw the man is using to build the wall is sometimes called cob. Another way of building a cob wall is to use bricks made of cob.

The woman in the picture below is making bricks for a new house. Look carefully at the picture of the bricks she has made, then answer the questions.

What material has the woman added to the mud to reinforce the bricks?

Straw, grass

What is this mixture called?

Cob

Would it be possible to add the straw or grass after the bricks have been made? When should the straw be added to the clay?

No, the straw should be added before the clay hardens into bricks.

Finally, the fourth video shows a different way to reinforce clay bricks. http://youtu.be/0oBwpFS4Euk. Watch the video to the end and then answer the questions. Or look at the pictures below.

Pouring water in to mix with the mud and straw.
Putting the mixture into a mould.
Packing the mud mixture into the mould.
Removing the mould.
Leaving the bricks to dry.

Do the bricks contain straw or stones?

In the video, they contain only clay/mud. In the pictures above they do contain straw and grass.

How does the man get all the bricks to look the same?

He fills a box (mold) with the clay, then tips the wet clay out of the mold before it is dry.

After making the bricks they are stacked in a large pile and then a fire is made underneath the pile. What do you think is the purpose of this procedure?

The bricks are baked (fired) to make them hard.

Make a list of all the different ways in which mud or clay can be made stronger when we want to use it to build a house.

The mud can be mixed with straw or stones.
The mud can be mixed with cement.
The mud can be packed inside a framework of sticks.
The mud walls can be built thicker at the bottom.
The mud can be shaped into bricks and then fired.

You may remember from the story Heitsi prepares for the hunt, that Heitsi belongs to the Khoikhoi people from the days before South Africa was a country. In those days there were no borders, no provinces, no towns or cities, and no roads. No-one 'owned' land; the land belonged to everyone who lived on it. Imagine that!

Like all the early people, the Khoikhoi had to make everything they needed, because there were no shops then! They had to use whatever materials were freely available.

The Khoikhoi people were nomads. That means they did not live in one place for long. They moved their homes and their belongings every few months, when the seasons changed. By moving around, they could always live near good grazing. Fresh green grass and trees meant there would be leaf-eating animals around to hunt. I also meant there would be good food around for themselves, and for their goats to eat.

Read the story carefully for clues on which materials were used to make a traditional Khoikhoi house.

Heitsi moves house

Heitsi's clan is on the move again. A few days ago, the clan packed up all their belongings and started their long trek to the place that will be their home for the summer months. The place where they lived had become dry and dusty and it was becoming more and more difficult to find good things to eat. They took apart their hut, which they will rebuild when they reach their destination.

During the long trek, everyone has to help carry things. Heitsi is carrying his own sleeping mat and karos, and his hunting weapons. He also has to keep an eye on the goats in case they wander too far from the clan.

After many days of walking, they arrived at the place that would be their new home. Now they can rebuild their house.

The framework of the house must be strong so that the house will stand firm. Heitsi's mother and aunties have found some young trees nearby and are cutting long, thin branches that will be perfect for making a frame for the house. Once they have cut the branches, they strip off the leaves.

The men bend the flexible branches into crescent (half-moon) shapes and tie them together with flexible strips of tree bark. This is how they build a dome-shaped framework for the house.

Can you see the framework of tree branches? Can you see what the house is made of?

You could draw attention on the photos that the framework is made of thin, flexible branches, and the hut is made of reed mats.

Women attaching the reed mats to the framework.

Once the framework is built, it is ready to be covered with reed mats. For this reason the house is called a matjieshuis (mat-house). Heitsi's mother and aunties made the mats by threading reeds together with string that she made from the long thin leaves of palm trees.

The whole family has to help with the floor of the house. They bring clay from a nearby river and Heitsi's mother makes the floor by stomping down the wet clay with her feet. Once the clay has dried, the floor will be smeared with animal manure. This is not as disgusting as it sounds - the manure seals the clay to prevent it from becoming sandy and dusty.

A fire-hole will be dug in the middle of the floor, with sleeping hollows (about 15 cm deep) around it. Soft plant material will be placed in the sleeping hollows, and this will be covered with mats and karosses to make comfortable beds for Heitsi and his family.

Heitsi loves his portable home. It is the perfect shelter. In hot, dry weather, the openings between the reeds allow air to circulate inside the house to keep it cool. It also lets in light. He knows that when the rains come and the reed mats get wet, the reeds will absorb water and swell out. Then they will seal tight and protect the inside of the house against leaks. During the cold months, the inside of the house will also be lined with animal skins to make it extra warm and comfortable..

Thinking about Hetsie's matjieshuis

QUESTIONS:

In the story we learnt how many different traditional materials were used by the Khoikhoi when they built their portable homes. Make a list of all the materials you can find in the story, and say how they were used. Use the table below for your list.

Type of traditional material	How was the material used?
Animal skin	Used for making a karos (soft skin blanket)
Flexible branches	Framework of the house (matjieshuis)
Strips of tree bark	Ties for the matjieshuis framework
Mats	Reeds
String for tying the reed mats	Twisted palm leaves
Clay	Floor of the hut
Animal dung (manure)	Sealing the floor of the hut
Soft plant material	Lining the sleeping pits

What does it mean when we say Heitsi's house is portable?

A portable house is a house that can be broken down, moved and built again in another place.
Write a paragraph to describe the materials and methods used by Heitsi's family to keep their home warm and dry during winter.

The family made warm beds out of plant material and covered them with mats and karosses. They made the beds around the fire, so everyone could sleep close to the fire. They built their house of reeds that would swell out in the rainy weather, to keep the inside of the house dry. They covered the house in animal skins for extra warmth.
How does Heitsi's mother strengthen the floor of the matjieshuis?

Heitsi's mother makes the floor from clay, which will be hard when it is dry. Then she covers the clay with animal dung that will form a seal on top of the clay. This prevents the clay surface from breaking up into dust.
Look at all the pictures of modern 'houses' below. Which one is the most like Heitsi's house? Why do you say so?

A brick house.

A caravan.

A tent.

The tent is most like Heitsi's house because it can be broken down quickly and it is light enough to carry to a new location.
Draw a picture of the floor plan of Heitsi's house.
If you have time in class, build a model of Heitsi's house, using any suitable building materials.

We saw that Hetsie's family used grass to make the reed mats for their matjieshuis. In Africa, many people make objects by using plant products, called plant fibres. The people weave and stitch the plant fibres together to make different objects, such as reed mats, baskets, or even thatch to make a roof for a house. This is also a type of traditional processing.

A man weaving a reed mat. http://www.flickr.com/photos/miusam/428068620/

Identifying objects made from plant fibre

INSTRUCTIONS:

Each of the following pictures shows an object made from plant fibre.

Identify what it is and how the people are using these objects

Object made from plant fibre	Description
http://www.flickr.com/photos/37743612@N05/4685092625/	AZulu "Ukhamba' beer basket for holding and storing Zulu beer. It is made by weaving grasses together.
	This roof is made from thatch which is dried grass packed tightly together.
http://www.flickr.com/photos/cameronparkins/210589508/	This person is wearing a straw hat to protect their face from the sun.
http://www.flickr.com/photos/christianhaugen/3657221524/	These houses are made from reed mats, similar to the matjieshuis.

Natural materials come from plants, animals or the Earth
Raw materials are materials that have not been processed.
Processed materials are raw materials that have been changed or refined by humans.
Humans have been processing materials from the earliest times.
In Africa, people have processed materials for hundreds of years, for example to make clay pots and woven products.

What are raw materials?

Raw materials are materials that have not been processed.

What are natural materials?

Natural materials come from plants, animals or the Earth.

What are processed materials?

Processed materials are raw materials that have been changed or refined by humans.

Which processing method did the Khoikhoi people use to make wood and bone hard and strong?

They used fire to dry the wood and bone slowly without burning it. This process is called fire-hardening.

Where did the Khoikhoi people find the material that they used to make their homes?

All the materials were found in nature.

How can sand and clay be made stronger if we want to use it to build a house?

Sand and clay can be made stronger by adding a binder like cement, and/or by adding reinforcing material like straw, pebbles or even steel reinforcements.

Look at the picture of a matjieshuis below. It is an old one and it was made differently to the one Hetsie's family made as this one does not use reed mats, but rather bushes that have been tied onto the frame. Which method do you think is better and why?

An old matjieshuis. http://www.flickr.com/photos/9511023@N03/4279851038/

Learners should say that the matjieshuis made by Hetsie's family is better as the woven reeds are stronger and hold together more firmly than the bushes which are just tied on to the frame.

Making objects out of plants is a traditional African process. There are different ways of doing it and different parts of the plants which can be used. The three pictures below all show photos of woven products, but they have been made using different plants parts. Write a description of each and say what kind of object you think it might be used for.

Woven product	Description
http://www.flickr.com/photos/rvoegtli/5404885227/	This is made from sticks or thick reeds which were bent when they were still green. It makes a very strong basket for carrying things.
	This is made from much smaller plant fibres which have been made into strings and stitched/woven together. it will be quite flexible and useful for making a bag or sack.
	This is made from bigger strips of leaves or reeds (maybe banana palm fronds cut into strips), which have been woven together. It could also be used to make a basket or bag which is not as strong as the first basket, but can also be used to carry things. Or it could be a mat.

How is this woman using a woven product. Think if you, or anyone in your family, uses any woven products in your daily life and write them down too.

A woman from Uganda. http://www.flickr.com/photos/amslerpix/6637298391/

A woman using a basket made from weaving plant sticks together to carry her fruit. Any possible answers where a learner might use a woven product.