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Why life on earth is possible

Module by: Siyavula Uploaders. E-mail the author

NATURAL SCIENCES

Grade 5

PLANET EARTH AND THE UNIVERSE

Module 20

THE EARTH AS A LIVING PLANET

ACTIVITY 1:

Why life on earth is possible

[LO 2.2]

What makes life on earth possible?

  • Let us try to determine which things are necessary for life on earth.

Read the following passage and try to find four things that are necessary for life on earth, as we know it.

Figure 1
Figure 1 (graphics1.png)
Man is used to seeing the sun rise and set every day. But do we always realise how important it is that it does happen? Sunlight contains energy that heats the earth and provides light
Figure 2
Figure 2 (graphics2.jpg)
.

We must remember that we cannot live on sunlight alone and that we would not have been here if it hadn’t been for plants. Plants have the wonderful ability to absorb sunlight and use it to produce food. When we eat the plants, our bodies absorb this food and we can live.

Figure 3
Figure 3 (graphics3.jpg)

However, plants need more than sunlight to produce food. They have to use their roots to draw the ingredients they need to make the food out of the soil.

Water is a very important ingredient, but there are also other ingredients such as iron and nitrogen that are necessary.

We would not be able to live on food and water alone. We also need oxygen to breathe. This oxygen is found in fresh air and is continuously being replenished by the plants. Plants take in the old air that animals and people have exhaled, and then make oxygen that is released into the air.

Four things are, therefore, essential for life on earth:

, ,

and .

ACTIVITY 2:

To be able to explain why the sun and plants are essential for life on earth

[LO 1.1; LO 1.2; LO 1.3]

Life without ENERGY is impossible.

Think of ten activities that you do every day and for which you need energy, and write them down here.

You get all the energy you need from the food you eat and the liquids you drink. All these foodstuffs originally come from plants. The plants use solar energy to produce it.

Complete the following table by writing down ten examples of food and drinks that you regularly ingest. Next to each one you must indicate from which plant it comes originally. (In some cases the plant was eaten by some other animal first, and then the product materialised, e.g. meat or eggs.)

Table 1
Example of food or drinks that you ingest regularly Plant from which the main ingredients originally come
   
   
   
   
   
   
   
   
   
   

Think of more reasons why the sun is essential for life on earth, and write them down.

Both humans and animals are dependent on plants as a source of food. However, there are other reasons why plants are important. Write down FIVE such reasons.

Do some research on the medicinal value of plants. Include at least two examples of plants of which the medicinal value was discovered in Africa or South Africa. (Read up in books and magazines and discuss this with your parents or elder brothers or sisters.).

ACTIVITY 3:

To be able to talk about the importance of trees

[LO 1.2; LO 3.1]

Let us focus our attention on trees.

1. When is it national arbour day this year (the date)?

2. Why are we encouraged to plant trees?

3. Why are scholars especially encouraged to plant trees?

4. Write a short poem about a tree.

Plan the poem as a group. The poem can be about a tall tree or about a young tree.

Write the poem in its final form here. Decorate your poem at home. You could also make a poster on which you write the poem and then the group could decorate it.

Figure 4
Figure 4 (graphics4.png)

Assessment

LO 1: SCIENTIFIC INVESTIGATIONLearners respond confidently to their desire to learn about natural phenomena; they investigate relationships and solve problems within the context of science, technology and the environment.

ASSESSMENT STANDARDS

we know this when the learner:

1.1 plans investigations;

1.2 takes the lead in investigating and collecting data;

1.3 evaluates data and communicates findings.

LO 2: CONSTRUCTION OF SCIENTIFIC KNOWLEDGELearners know, interpret and apply scientific, technological and environmental knowledge.

ASSESSMENT STANDARDS

we know this when the learner:

2.1 recalls significant information;

2.2 categorises information.

LEARNING OUTCOME 3:

Science, SOCIETY and the environmentLearners are able to show understanding of the underlying connections of technology, the community and the environment.

ASSESSMENT STANDARDS

We know this when the learner:

3.1 understands science and technology in the context of history and indigenous knowledge:

Memorandum

Activity 1

Sunlight / sun energy, soil / nutrients, water and oxygen (plants will also be mentioned: acknowledge that it is correct, but that we are first discussing the non-living things. Use the opportunity to make learners aware of the value of plants and the necessity of conserving them - talk about the indiscriminate destruction of forests/trees, overgrazing, etc.)

ACTIVITY 2

Examples:

  • Bread wheat
  • Porridge maize/grain
  • Sugar sugar cane
  • Meat grass/grain
  • Egg grain/maize
  • Fruit fruit
  • Fruit juice fruit
  • Imitation soft drink often sugar cane, little or no fruit
  • Ice cream grass/grain
  • Butter grass/grain
  • Milk grass/grain
  • Fish algae/aquatic plants
  • Use of sun: we would not be able to seewe would have died of cold

energy for work performance comes mainly from the sun (e.g. petrol)

  • Plants: shade (prevents overheating of soil)

wood for fires (energy) and building medicine

  • Plants as medicine Give a lot of attention to this assignmentTalk about indigenous knowledge: 70 % of South Africans consult traditional healers

Examples of medicinal plants in SA (there are many)

  • Buchu (ibuchu, boegoe): leaves and roots for kidneys and general problems of the excretory system, bruises, rheumatism, chewed for stomach ache
  • Cape aloe (ikhala, bitteraalwyn): leaf sap for conjunctivitis, arthritis, eczema, skin irritations, burns and bruises
  • African wormwood (umhlonyane, wildeals): leaves for tea for upset stomach, ground leaves emit vapours that are inhaled for headache and colds, taken for measles and colds, enemas for constipation, worms
  • Wild willow (umngcunube, wilde wilger): bark for aspirin

ACTIVITY 3

  1. Every year from 1 to 7 September: there is always a week-end in this period.
  2. Many reasons, e.g. ozone layer, shade promotes bird and other animal life, good for soil.
  3. They invest in their country, they are the next generation that has to take responsibility for the land, they make their parents aware of the importance of trees and environmental conservation and so the message spreads through the community.

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