4.6 Role of water

Natural sciences

Grade 8

Environment

Module 38

The role of water in nature and its role as a resource

Activity:

To be able to explain the value of water and the water cycle

[lo 1.3; lo 2.3; lo 2.4]

Our planet looks blue from outer space because of the water on its surface.

Water is indispensable for life on our planet. Without water ecological survival would not be possible.

Our planet is equipped with a certain quota of water – just as a spaceship would be. The water is not replenished from outer space, but has to CIRCULATE. Thus the WATER CYCLE is an extremely important aspect of nature. It is also most effective if humans do not disturb it.

The Water Cycle

Draw a representation of the water cycle as you understand it. Use explanatory captions. Use the table on the following page as a guideline.

Assessment of WATER CYCLE SKETCH

Were you able to represent basic components and definitions GRAPHICALLY?

[LO 2.3]

El Niño, droughts and floods

• On comparing the rainfall statistics of South Africa to those of other countries, one sees very clearly that South Africa is an arid country.
• Only some of the larger rivers flow permanently.
• Furthermore, our climate and rainfall patterns are determined by phenomena such as El Niño. This is a world-wide weather phenomenon and precautions must be taken to cope with it.

1. Find out more about El Ni ñ o and report back to the class. Make a brief summary of your notes.

2. Find articles on droughts and floods in South Africa and bring them to class. Swap information and articles. Make notes on the subject.

[LO 1.3]

Use graph paper and draw two column graphs in different colours to represent the rainfall patterns in the two provinces.

Activity:

To look into the value of water and its use in and around the house

[lo 2.3; lo 3.2]

Water consumption at home

Ask your parents or guardians for their municipal accounts.

• Write down your domestic water consumption for six months (three summer months and three winter months).

Summer months: 1. ......................... 2. ......................... 3. .........................

Winter months : 1. ......................... 2. ......................... 3. .........................

• Do you think that your water consumption is excessive?

Saving water at home

How can your family contribute towards saving water? What can YOU do?

• Make a list of your best suggestions:

Assessment of CLASS DISCUSSION

Were you able to make feasible suggestions concerning WATER CONSERVATION?

[LO 3.2]

Activity:

To examine the adaptations of plants and animals with regard to water shortage

[lo 1.3; lo 2.3]

Plants:

• In a previous module reference was made to plants that can be classified into three groups, according to their water requirements.

Name the three groups and give an example of each.

• Plants have numerous adaptations and survival strategies, especially with regard to water shortages.
• Xerophyte leaves have been modified to thorns in cases such as the cactus plant groups. Other plants, such as the aloe, about which you had to do a project, store a great deal of water in their fleshy leaves through protein bonding.
• The leaves of mainly xerophytes are thick and fleshy and unpleasant or bitter to the taste to deter animals from eating them. In this way they prevent the plant from being robbed of its valuable moisture.
• The leaves of plants that have been adapted to arid conditions for survival are often sessile (no leafstalk) and they are arranged in such a way that any water that collects on the leaf (e.g. dew) will run down the stem so that the roots can absorb it.
• The leaves of some other plants roll up when it is very dry, so that evaporation is limited. For example, see what the leaves of the maize plant look like when it hasn’t rained for a long time.