Wood comes from trees that grow all over the world either in natural forests or in plantations that are planted by man.

When trees are fully-grown, especially in plantations, they are chopped down. The branches and the trunks of weak trees are used to make pulp that is used to make paper. The tree trunks are taken to saw mills where they are cut into planks. The wood is then called timber.

Figure 1

Wood can be used for many things, for example, furniture, doors, boxes and toys. Musical instruments like the guitar and the violin are made of wood.

The pulping of wood happens in factories. The wood pulp is mixed with chemicals and water and then rolled out into thin sheets and dried to make paper.

Other uses of wood

Look at your pencil and pencil crayons. What are they made of?

Scrap planks are often used in informal settlements to build shelters and this is better than having no shelter at all.

In tropical countries where it rains a lot wooden houses are often built on poles so that the inhabitants stay dry during the rainy season and also so that unwelcome guests like snakes are kept out.

If wood is looked after properly it will withstand different weather conditions and will protect the inhabitants against heat and cold.

Make a poster containing the following information.

How wood is used in the building industry.

OR

Products made from wood.

Pictures and drawings that illustrate your project will count in your favour.

There is a lot of clay available in the crust of the earth. There are different types of clay. Ceramics are made by baking clay. Different types of clay make different kinds of ceramics.

See which items are made from ceramics.

Figure 2

Ceramics is used to make electrical isolators. It prevents electricity from flowing into steel poles or frames.

Let’s see how a ceramic pot is made from clay.

1. Clay that is moist can be easily moulded into a shape. This is the composition of wet clay:

Figure 3

2. Once a clay pot has been made it is left at room temperature to become dry. The water molecules in the clay evaporate and the clay shrinks and gets hard.

Figure 4

This is how the dry clay is composed.

3. When the clay is dry it is baked (fired) in a pottery kiln (pottery at ± 980°C and ceramics at between 1 200°C and 1 700°C).

This is how the clay is composed now.

Figure 5

There is too little space between the clay molecules to allow water through.

Find information and report in writing about a bird that uses clay to build its nest.

2. In what country are these birds found?

3. Where does the bird build its nest?

Total: 10

Figure 8

Of all the materials used to make things metal is one of the most important. There are certain jobs that can only be done by using metal. Let’s see how your life depends on metals from morning till night. Just think of transport and farming. The first metal items existed as long ago as 9500 BC: gold; silver; copper and iron.

Metals can be recognised from their appearance:

Metal is usually shiny.

Metals are good conductors of heat and electricity.

Many are suitable for making sounds. When you hit metal, it rings. Church bells are made of bronze.

Metal can be moulded into shapes. Lead is a soft, flexible metal. Sheets of lead used to be used on roofs, especially of churches and schools.

Steel is a mixture of iron and other ingredients. Coins are also made of a mixture of metals.

Interesting facts:

The bottom of a cooking pot must be a good conductor of heat.

Not all metals are suitable for cooking foods in.

Cast iron, stainless steel, aluminium, steel and copper are used to manufacture cooking pots.

When steel is left in the rain it rusts. Water and oxygen in the air have an effect on the iron in the steel and combine to form a new material, namely rust.