1.2 Hydroelectricity

Natural sciences

Grade 8

Energy: electricity, heat and light

Module 3

Hydroelectricity

Activity:

To understand and evaluate electricity as a source of energy

[lo 1.1, lo 1.2, lo 1.3]

We live in a very dry country, but we do have two large permanently flowing rivers and ESKOM has erected two large hydroelectric power stations. One is situated close to the Gariep Dam in the Free State and the other is at the Van der Kloof Dam near Petrusville.

Assignment 1:

Find out where these two large dams (and any other large dams), are situated and draw a map of South Africa to indicate their positions.

Assessment of location of Dams

Were you able to identify the dams correctly?

Hydroelectricity can basically be explained in brief by means of the following points:

• The downward movement of water, due to gravitational pull, energises the molecules of water.
• The falling water turns a turbine and converts the energy of the molecules to electric energy.
• The transfer of energy to some or other turning mechanism has been in use for more than 2 000 years.

Assignment 2:

Read and find out more: Visit the Internet and use a search engine, using words like “aqueduct” and “water wheel”.

The water wheel

Aqueducts

Give feedback to the class.

Activity:

To compare and evaluate hydroelectricity and coal burning as sources of energy [lo 2.2, lo 2.3]

Assignment 1:

Complete the following table dealing with coal-burning power stations as opposed to hydroelectric power stations with regard to the following headings: Decide whether you are dealing with an advantage or disadvantage in each instance and mark the corresponding column.

Conclusion:

Assessment

LO 1: Scientific investigations:

The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

This is evident when the learner:

• plans investigations;
• conducts investigations and collects data;
• evaluates data and communicates findings.

LO 2: Constructing Science Knowledge:

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

This is evident when the learner:

• categorises information;
• interprets information;