2.3 Making energy available to people

Natural sciences

Grade 4

Energy and change

Module 28

Making energy available to people

MAKING ENERGY AVAILABLE TO PEOPLE

Energy from sunlight is stored in and around the earth in several ways. (In some instances temporarily, as when the earth is warmed by the sun, or for longer periods of time, for instance when it is fixed in food). The stored energy can be released later and be used.

Let us take a look at some of the means by which it may be released

Activity:

Using wind as a source of energy to our advantage

[lo 1.1, 1.2, 1.3, 2.1]

See how many of the following idiomatic expressions that have developed around the idea of wind are known to you?

• We got wind that you were coming (we were given a hint)
• His talk was all wind (it was insubstantial)
• Between wind and water (a vulnerable spot, as the part of a ship that is normally below water but is exposed when the ship rolls)
• How the wind blows (what appears probable)
• In the wind (about to happen)
• Three sheets in the wind (intoxicated or drunk)
• Sail close to the wind (come near the limits of danger)
• Take the wind out of someone’s sails (destroy someone’s advantage)

What is wind?

Blow on your hand. What do you notice?

We cannot see the wind, but we can feel it when it blows against our faces or ruffles our hair.

Washing dries quickly if it is hung out in the wind.

Do you know the reason for this?

How does wind occur?

Complete the sentences to explain the illustration by supplying the missing words:

1. By day the sun . It .

the land.

1. Warm air .
2. Cooler air moves from the to the

to take the place of the warm air.

1. This is how originates.

Make a windmill

• Use stiff paper. Cut it according to the instructions on the illustrations.

• Will this windmill turn in a room where there is no wind?

• What could you do to make it turn?
• Discuss suggestions about how to increase the windmill’s turning speed with your friends and report your ideas to the class.

Folding a small paper glider:

• Fold a sheet of A4 paper in half lengthways.
• Unfold the sheet of paper and fold the two top corners to the central fold so that the top edges lie together.
• Fold the new corners to the central fold, forming a sharp arrow point.
• Fold back the arrow point to the point at which the other points meet.
• Fold along the original lengthways fold again to “close” the structure.
• Fold the bottom corners separately to form wings.
• Fold back both wings along a line lying parallel to the central fold.
• Hold below and throw gently, noting how far the glider glides!
• You may experiment to see which folding pattern allows the glider to glide better. Demonstrate this to the class and motivate your explanation.

Ways in which wind is used to the benefit of people

People have always made use of the power of wind to achieve things.

People have used the wind to their advantage. Sailors use the power of the wind that blows against their sails to drive their ships.

Windmills have been used to grind wheat and wind pumps pump water from below the ground.

Class project

Let’s build a kite! First name and describe the materials that we could use for this project. Then form groups to build kites.

Assessment

LEARNING OUTCOME 1: SCIENTIFIC INVESTIGATIONSThe 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.

Assessment Standard

We know this when the learner

1.1 plans investigations;

• leads investigations and collects data;
• evaluates data and provides feedback on observations.

LEARNING OUTCOME 2: CONSTRUCTING SCIENCE KNOWLEDGE

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

Assessment Standard

We know this when the learner

2.1 recalls significant information.

Memorandum

What is wind?

I feel air on my hand.

The wind shakes drops of water from the washing. The vapour from the washing disappears into the air.

Where does the wind come from?

Complete the sentences by using the missing words in order to explain the illustration:

1. shines, warm

2. rises

3. sea, land

4. wind

Make a windmill

Use a sheet of firm paper. Fold it according to the instructions on the illustrations.

Does a windmill turn in a room where there is no air current (wind)? No!

What can you do to make it turn? I can run while holding it in the air.