- Explain the terms “deforestation” and “re-forestation”.
5.2 Give two examples each of hardwood and softwood.
5.3 Give one example of an indigenous tree found in South Africa.
- Why do you think the Knysna area is well-suited for forests?
- How can one tell how old a tree is?
- Take an old map and make an envelope out of it.
Activity 6
To demonstrate an understanding of how materials (metals) can be recycled
- Steel is the material that is recycled most. Scrap steel is placed in a furnace and melted by electricity that arcs between two carbon electrodes. Limestone and other materials are added to the molten steel to remove impurities. The steel produced is mostly used for beams and thick plate.
- The recycling of aluminium is very important because most of the ore required to produce aluminium must be imported. There are many different kinds of aluminium – up to 15 different kinds. Most beer cans, cooldrink cans and food cans are made from aluminium. Cans brought to collection centres are crushed, baled, and taken to a mill. Here they are melted and formed into bars. These bars are rolled into sheets and cut into disks from which cans are formed.
6.1 Name five different kinds of metal.
6.2 In which format can steel be bought? Make sketches of the shapes.
- Make a list of products that are sold in cans.
6.4 Make a production diagram of the photo’s from a food can company.
Activity 7
To form an understanding of what incineration and landfills are and to understand the positive and negative impact of these on the environment
- Most of our waste goes to landfills. A landfill is a dumpsite where soil is used to cover the waste, so as to prevent the waste from blowing away and to keep down odours. For this process heavy machinery is needed to dig the holes and to cover the waste. In some countries these areas must have thick liners to prevent toxic liquids from leaking out. Unfortunately this is not yet enforced in South Africa. This means that there is a possibility that underlying groundwater can be polluted by leaking liquid. People further object to landfills for a number of reasons; they anticipate waste being blown about, foul odours, rodent infestations, increased truck traffic and lowered property values.
- Many municipalities have invested in incinerators. These gigantic ovens burn tons of waste to ash. Incinerators use the heat from burning waste to produce steam which is used to drive turbines to produce electricity. Incinerators require less land than waste dumps and they do not pose a potential threat to groundwater. Incinerators have drawbacks:
- Toxic air pollution.
- Disposal of the ash.
- More expensive than landfills.
- The use of incinerators undermines recycling programmes.
7.1 Name two advantages of incinerators and two of landfills.
- Name two disadvantages of incinerators and two of landfills.
- Explain why the use of incinerators undermines recycling. Situation
Your younger brother is turning five. He desperately wants a lampshade with his favourite cartoon character for his room. As it turns out, there are no lampshades available in the shape of that character. Your parents desperately need your help to design and make this present.
