Earth And Beyond [grade 7 English]

WESTERN CAPE PRIMARY SCIENCE PROGRAMME A SHORT LEARNING PROGRAMME ON THE NATURAL SCIENCES THEME:

EARTH

AND

Grade 7

BEYOND

ACTIVITIES

1. What shape is our Earth? 2. Where on Earth is the land, the water and the air? 3. Finding out about the Earth’s atmosphere 4. Our Earth is a planet 5. There are nine planets around the sun 6. The inside of the Earth 7. Finding out more about our home planet (a) We have volcanoes in our planet (b) We need minerals from the Earth’s crust in our lives

We welcome the wide use of these materials. Please acknowledge the PSP.

© PSP 2001

DEVELOPED BY WESTERN CAPE PSP TEAM AND TEACHERS This learning programme will work towards the following learning outcomes in the Natural Sciences

s LO1: 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

s LO2: Constructing Science Knowledge The learner will know and be able to interpret and apply scientific, technological and environmental knowledge

s LO3: Science, Society and the Environment The learner will be able to demonstrate an understanding of the interrelationships between science and technology, society and the environment.

All images of the planets courtesy of NASA. Our thanks to the South African Astronomical Society for the information about the planets.

Course presented by Rose Thomas and Sandra Mahote Booklet designed by Welma Odendaal and illustrated by Janet Ranson and Nicci Cairns Western Cape Primary Science Programme Edith Stephens Wetland Park Lansdowne Road Philippi 7785 PO Box 529 Howard Place 7450 Tel: 021 691-9039 Fax: 021 691-6350 e-mail: [email protected] website: www.psp.org.za

Contents • • •

This booklet illustrates an example of a short learning programme for Grade 7. It develops concepts, skills, attitudes and language in a step-wise fashion. It includes activities and tasks for learners, teacher tasks, support materials and assessment suggestions.

1 . . . . . . . . . . . . . .Activity 1

What shape is our Earth?

2 . . . . . . . . . . . . . .Activity 2

Where on Earth is the land, the water and the air?

3 . . . . . . . . . . . . . .Activity 3 A. 6 . . . . . . . . . . . . . . . . . . . . . . . . .B. 8 . . . . . . . . . . . . . . . . . . . . . . . . .C.

Finding out about the Earth’s atmosphere The layers of the atmosphere Our air is precious but we pollute it

11 . . . . . . . . . . . . .Activity 4

Our Earth is a planet

13 . . . . . . . . . . . . .Activity 5

There are nine planets around the sun

15 15 16 17

The . . . . . . . . . . . . .Activity 6 . . . . . . . . . . . . . . . . . . . . . . . .A. . . . . . . . . . . . . . . . . . . . . . . . .B. . . . . . . . . . . . . . . . . . . . . . . . .C.

inside of the Earth The inside of the Earth is made up of layers A play dough model of the inside of the Earth How big is our Earth?

Finding out more about our home planet 20 . . . . . . . . . . . . .Activity 7 20 . . . . . . . . . . . . . . . . . . . . . . . .A. We have volcanoes in our planet 25 . . . . . . . . . . . . . . . . . . . . . . . .B. We need minerals from the Earth’s crust in our lives 26 . . . . . . . . . . . . .Suggested work scheme for this learning programme Assessment and Recording Suggestions 27 . . . . . . . . . . . . .Assessment sheet for assessing a task 28 . . . . . . . . . . . . .Recording sheet for task assessment 29–30 . . . . . . . . . .Blank Assessment sheets 31 . . . . . . . . . . . . .Codes for Assessment Support materials and task cards to photocopy 32 . . . . . . . . . . . . .Activity 2

Map of the world

Readings about the Earth’s atmosphere 34 . . . . . . . . . . . . .Activity 3 35 . . . . . . . . . . . . . . . . . . . . . . . .Graph paper 36 . . . . . . . . . . . . . . . . . . . . . . . .A. Air and living creatures 37 . . . . . . . . . . . . . . . . . . . . . . . .B.

Layers of the atmosphere

38 . . . . . . . . . . . . . . . . . . . . . . . .C.

What pollutes the air?

39 . . . . . . . . . . . . .Activity 4

Reading about planet Earth and the sun

40-43 . . . . . . . . . . .Activity 5

Set of “Nine Planets”

44 . . . . . . . . . . . . .The solar system chart 46 . . . . . . . . . . . . .Planet fact sheet 47 . . . . . . . . . . . . .Task card “The Solar System” 48 . . . . . . . . . . . . .Activity 6

Cut-away section drawing to show the inside structure of the Earth

48 . . . . . . . . . . . . .Reading about the Earth’s inside structure 49 . . . . . . . . . . . . .Play dough recipe 50 . . . . . . . . . . . . .Task card “Inside the Earth” 51 . . . . . . . . . . . . .Task card “How big is our Earth?” 52 . . . . . . . . . . . . .Activity 7 Reading about the Mount St. Helens volcanic eruption 57 . . . . . . . . . . . . .Readings about other volcanoes 58 . . . . . . . . . . . . .Diagram of a volcano 59 . . . . . . . . . . . . .A. Task card “Comparing a demonstration of a volcano and a real volcano” 60 . . . . . . . . . . . . .B. Task card “So many things come from the Earth’s crust” 62–63 . . . . . . . . . .Task card: What does ‘ling of kwaito’ Arthur Mofekate need? 64 . . . . . . . . . . . . .Mineral fact sheet Cover . . . . . . . . . .Mind map of Earth and Beyond

Activity 1 Key concepts Teacher task

Learner task

What shape is our Earth? • The Earth is round like a ball

Give learners a box with different shapes

Choose a shape which best resembles the shape of the Earth from the items in the box and explain why you decided to choose that shape.

Teacher task

1. Find pictures in newspapers or old magazines to show evidence that the Earth is round. 2. Supply learners with newspaper, scrap sheets of white A4 paper, flour and water to make a model of the Earth.

Learner task

Make a paper model of the Earth by following the steps below: 1. Crumple 10 sheets of newspaper together to make a ball shape. 2. Tear two or three sheets of white A4 paper into thin strips. 3. Make a glue paste out of flour and water. 4. Spread the glue onto the strips of white paper with your fingers. 5. Bandage the strips around the ball of newspaper until the ball is completely covered. 6. Put your Earth paper model in the sun to dry.

1

Activity 2 Key concepts

Teacher task

Learner task

Pantihose covering the model of the Earth

Teacher task

A s se ss m en t Activity

2

2

Where on Earth is the land, the water and the air ?

• The Earth has land, water and air • More than two thirds of the Earth’s surface is covered by water, and nearly all of that water is in oceans • There is a very thin layer of atmosphere covering our Earth

Give each group of learners a map of the world to cut out continents and a piece of pantihose to show how thin the Earth’s atmosphere is. 1. Draw the equator onto your Earth paper model and make a mark to show where the North pole Look! Yes! It is and the South pole are. I’ve used up because most of 2. Cut out continents from the my blue the Earth is map of the world. crayon! covered in water. 3. Paste them onto your Earth paper model. Use an atlas to help you put the continents more or less onto their correct positions. 4. Colour the land brown and colour the water blue. 5. Put on the air by stretching the pantihose over your Earth paper model. 1. Facilitate a discussion and make sure that the learners understand the following: A that most of our Earth is covered by water (nearly 70% of the Earth’s surface), and A the atmosphere that covers the Earth is a very thin layer. 2. Use the following questions to help the discussion: A of which colour is there most on your model? A what does this tell you?

Where on Earth is the land water and the air?

What we want to assess

What we expect from learners

Making the paper model of the Earth

a The model should be spherical a The equator should be drawn more or less in the correct position i.e. the model should have almost 2 equal halves to represent the Southern Hemisphere and the Northern Hemisphere a Position of the North pole and the South pole should be clearly marked on the model a Land masses should be placed in more or less the correct position a Land should be coloured brown, the sea blue and the pantihose should be stretched over the model to represent the thin atmosphere

Activity 3 Key concepts

Finding out about the Earth’s atmosphere • There is a very thin layer of gases around the Earth called the atmosphere • The atmosphere is a mixture of gases (mainly Nitrogen, Oxygen and Carbon dioxide) • These gases occur in certain proportions: Nitrogen 78% Oxygen 20% Carbon dioxide less than 1% Other gases 1% • Air is essential for life

A. The Earth’s atmosphere

all these gases are mixed together

1. Explain the following to the learners: A Around the Earth there is a very thin layer of gases called the atmosphere. A The atmosphere is a mixture of gases that occur in certain proportions. 2. Also explain the pie chart below that shows what proportion of each gas there is in the air. 3. Supply the learners with the reading about “The Earth’s atmosphere is a mixture of gases” (see page 34). The Earth’s atmosphere is a mixture of gases The air we breathe is a mixture of gases that surround the Earth in layers. Air keeps the Earth’s surface at just the right temperature to support life. These layers of air and other gases are also called the Earth’s atmosphere. 20% oxygen

1% argon and other rare gases less than 1% carbon dioxide

that’s what we breathe!

78% nitrogen

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The air we breathe also contains the following: A Water vapour A Fumes called hydrocarbons, which come from car exhausts, factories and fires A Dust particles A Other gases, in very small amounts, for example, ozone, argon, neon, helium and krypton.

Learner task

Read the information about the Earth’s atmosphere and complete the tasks below: 1. Draw a bar graph to show how much of each gas is in the air.

ee I can’t s or gen any Oxy … Nitrogen

A GRAPH TO SHOW THE GASES THAT CONSTITUTE AIR

80% 70% 60%

Gases in percentages

50% 40% 30% 20% 10% 0%

Nitrogen

Oxygen

Carbon dioxide

Others

Gases that constitute air 2. Which gas makes up most of the air?

Teacher task

Air and living creatures and plants

Supply the learners with the reading “Air and living creatures and plants” (see page 36). • We cannot see or taste air RS • We can detect changes in air temperature NOTE TO TEACHE on our skins. stand Make sure learners under xide to We can feel the air moving around us. that plants use carbon dio t of • We can hear air moving as wind. make their own food as par . sis the Without air there would be no life on Earth. People can survive for the process of photosyn gen oxy off e giv y the This is when about a month without food, and a few days without water ver, we Ho e. her osp atm the o int but we cannot survive without air for more than a gen plants also ‘breathe’ in oxy few minutes. own to release energy for their All living things need air. All animals as . growth and development well as plants ‘breathe’ and use oxygen and give off carbon dioxide to stay alive.

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Why do we breathe air?

When we breathe in, air goes into our lungs. The oxygen in the air goes into the blood vessels surrounding our lungs. The oxygen is carried by the blood to every cell in our bodies. Here the oxygen is used to break down the food in the cells, and release the energy stored in food. We need the energy to move, think, breathe, work and play. After the energy has been released, carbon dioxide gas is given off and carried by the blood back to the lungs. The carbon dioxide is released into the lungs where it mixes with air and is breathed out. All animals and plants use oxygen and give

Learner task

A s se ss m en t Activity

3

off carbon dioxide in order to produce the energy for them to grow and develop. However, plants also use carbon dioxide from the air to make food. Plants take carbon dioxide from the air and water from the soil and energy from the sunlight to make food. This process is called photosynthesis. Photosynthesis means ‘making with light’. The food that plants make is called starch. When we eat foods containing starch such as mealie-pap or potatoes, this starch was made by the mealie plant and the potato plant. During photosynthesis plants give out oxygen into the air.

Read about air and the living things and discuss the following questions in your groups. 1. Why is oxygen important for all living things? 2. How is oxygen carried to every cell in our bodies? 3. What do plants use carbon dioxide for? 4. Where do plants get carbon dioxide from?

A. The Earth’s atmosphere

What we want to assess

What we expect from learners

A bar graph to represent the air as a mixture of gases

1. The graph must have: a a suitable heading a axes correctly labelled a a suitable scale a the bars shaded a the points accurately plotted 2. The graph must be plotted with the correct amounts of gas present in the air. 3. Nitrogen is the gas that makes up most of our air.

The question about air and living things

Correct answers to the questions: a) Oxygen breaks down the food in the cells of our bodies and the energy that all living things need is released. b) The blood from our lungs carries oxygen to every cell in our bodies. c) Carbon dioxide is given off into the air when plants and animals breathe. d) Plants use carbon dioxide for making their own food.

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B. The layers of the atmosphere Key concepts

• The atmosphere extends to about 80km above the Earth’s surface • The atmosphere is made up of layers • All the air that we need for breathing occurs in only the first 10km of air above the surface • The atmosphere protects the Earth’s surface from dangerous sun radiation and from dust and rocks in space

Teacher task 1. Supply the learners with a drawing showing the layers of the Earth’s atmosphere and the questions about each layer. (See page 37 to photocopy for learners.) 2. Allow the learners to discuss the questions in their groups. 3. Make sure that the following points come out in the discussion: A The atmosphere extends to about 80km above the Earth’s surface A The atmosphere is made up of layers. A All the air that we need for breathing occurs in only the first 10km of air above the surface. A The atmosphere protects the Earth’s surface from dangerous sun radiation and from dust and rocks in space. THE LAYERS OF THE ATMOSPHERE IONOSPHERE This layer absorbs dangerous rays from the sun. Radio waves coming fr om Earth reach this layer and are bounced back to a different part of the Earth where they are picked up by peoples’ TVs and radios. This is how radio programmes are transmitted around the world. MESOSPHERE This layer is very cold (–100°C). It protects the Earth from rocks (meteors) and dust that fly into the atmosphere from space.

STRATOSPHERE This layer is like a shield. It protects the Earth and living things from the sun’s dangerous rays.

TROPOSPHERE This layer has all the air that we need for breathing. All animals and plants live in this layer. This layer has water vapour and clouds and this is where we find different kinds of weather. The gases making up the Earth’s atmosphere become less and less the further you go away from the Earth until there is no atmosphere at all in space. SEA LEVEL Half of the atmosphere is below here

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Learner task

1. Look at the drawing of the Earth’s atmosphere. 2. In your groups discuss the questions about each layer. (a) In what layer of the Earth’s atmosphere are plants and animals able to survive? Give a reason for your answer. (b) Mountain climbers use oxygen when they climb to the top of Mount Everest. Why do you think they must carry extra oxygen? (c) What does the stratosphere do? (d) Can a person survive in the Mesosphere? Give a reason for your answer. (e) What would happen if the Earth had no atmosphere?

in the troposphere, of course!

where do you live?

A s se ss m en t Activity

3

B. The layers of the atmosphere

What we want to assess

What we expect from learners

Questions about the layers of the atmosphere

Correct answers to the questions about the layers of the atmosphere i.e. (a) Plants and animals live in the Troposphere. This is because the air that they need to breathe is in the Troposphere. Also in the Troposphere they are protected from dangerous sun’s rays and rocks and dust from space. (b) They must carry extra oxygen because as you go further away from the Earth’s surface, the amount of air becomes less. So there will not be enough oxygen. (c) It protects the Earth and living things from the dangerous rays of the sun (d) People cannot survive in the Mesosphere because it is too cold there and people are not protected from space dust and rocks. They are also not protected from the sun’s dangerous rays. (e) There would be no life on Earth. This is because there would be no oxygen for the animals and plants to get energy. There would be no carbon dioxide for the plants to make food. There would be no protection from the sun’s dangerous rays and no protection from space rocks and dust.

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C. Our air is precious but we pollute it Key concepts

Teacher task

• The same air is used over and over again in the atmosphere • Many activities carried out by people pollute the atmosphere • Pollution of the air is dangerous to living things

1. Lead a class discussion about how air is polluted. Use the picture that shows what pollutes our air to help the discussion (See page 38.) 2. In order to make sure that the learners understand that the same air that we pollute gets used over and over again, ask questions like: “Where does this polluted air end up?” (The direction of the arrows in the picture shows that the same air is used over and over again). 3. Supply the learners with the reading “The air is precious”. (See page 38.)

The air is precious The Earth’s air is the only air that we have. It is the same air that our ancestors breathed. It is the same air that the dinosaurs once breathed. We breathe the same air that our dogs and cats breathe. The air we breathe is the same air that has passed through our motor car engines and factory chimneys and the plants outside. The same air is used over and over again because it is the only air that we have. We can’t get any more air from anywhere else. When we make the air dirty from engines and factories, we call this air pollution. WHAT POLLUTES OUR AIR? This picture shows all the different things that pollute the air. The polluted air is used again and again.

8

Air pollution We say that the air is polluted when it becomes dirty. Substances that make the air dirty are produced in many different ways: A When we burn fossil fuels (coal and oil) in power stations to make electricity A When we make things that require burning and heating in factories A When we drive motor cars which always give off fumes A When we burn rubbish and motor car tyres A When we burn grass, bushveld and trees

ugh! why do we have to breathe your smelly fumes?

Strong sunlight interacts with the exhaust fumes from motor vehicles and this can produce poisonous gases. Sometimes we can see and smell these gases. They have a brownish colour and we call this smog. Smog is dangerous to plants and animals.

Learner task

1. Participate in a class discussion about things that pollute the air. 2. Read about “Air is precious” and “Air pollution” and answer the questions that follow: (a) What are some of the things that pollute the air?

The things that pollute air are: smoke from power stations, fumes from car exhausts, smoke from burning and smoke from factories. (b) Write to explain why some people are concerned that air is becoming polluted. Air pollution People are concerned about polluting the air.

whew! this pollution is really bad for me!

The reason why people worry is that this is the only air we have on Earth. that we use the same air over and over again, but if we make it dirty then we will only have dirty air to use. Another reason is that dirty air is dangerous to living things. Another reason is

(c) Write a praise poem about air. For example:

My precious air Without you I have no life My parents my, my friends, my cat and everybody. One single breath and my whole body is alive! Trees big and small, Beautiful flowers with insects around depend on you! Without you we all have no life. Thank you for being around for us 9

A s se ss m en t Activity

10

3

C. Our precious air that we pollute What we want to assess

What we expect from learners

Writing a paragraph to explain why people are concerned about air pollution

The paragraph must: a have a heading a have sentences that explain why people are concerned about air pollution a have sentences that make sense a contain key words about pollution e.g. burn, fumes, smog, factories etc.

Our Earth is a planet

Activity 4 Key concepts

Teacher task

• The Earth moves in space and it is a planet • The Earth rotates on its axis and revolves around the sun in its own orbit • It is the only planet that has life as far as we know • The Earth gets its heat and light from the sun • The sun is a star and not a planet 1. Below is a picture of the Earth.

polar ice cap

Asia

continent of Africa

clouds Great Lakes Atlantic Ocean South America

clouds

Island of Madagascar

2. Find any other picture of Earth that shows its physical features. 3. Show learners the pictures and ask the following questions to stimulate their curiosity about our Earth. Earth – Our Home Planet A What continents can you see? A Can you see any rivers and islands? A What are the white marks? Do you think they are fog, ocean currents, clouds or waves? A Can you see both polar ice caps? 3. Give learners a reading about planet Earth and the sun. (See “The Earth is a planet” and “The sun is a star” page 39.)

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Learner task

1. Complete the following table to compare our Earth and the sun. Questions 1. Is it a planet or a star? 2. What is it made of? 3. Does it give out light and heat? 4. Which is bigger, the Earth or the sun? 5. Can life survive on it?

Yes, the sun is much, much bigger. Earth is a planet. The sun is a star.

SUN = STAR

EARTH

SUN

planet rock no small yes

star very hot gases yes big no

The sun just looks smaller because it is very far away!

2. Write sentences to compare the differences between planet Earth and the sun. (Use the table to help you), e.g.

Earth is a wonderful place to live on!

1. The Earth is different from the sun because it is a planet whereas the sun is a star. 2. Earth is made up of rock whereas the sun is made up of very hot gases. 3. The sun gives off light and heat whereas the planet Earth gets its heat and light from the sun. 4. The sun is bigger than the Earth. 5. Planet Earth has living things such as plants and animals whereas living things can never survive on the sun. live! That’s where I

It’s the ONLY place to live! 12

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Activity 5 Key concepts

Teacher task

Learner task

There are nine planets around the sun • There are nine planets that revolve around the sun • Each planet revolves around the sun in its own orbit • The sun and all the planets that move around it form the solar system • Each planet moves at its own distance from the sun • Each planet can be recognised by its appearance

1. Explain to the learners that there are nine planets altogether that revolve around the sun. 2. Give each group of learners a set of the “Nine Planets” (page 40–43). 1. Read about the different planets and answer the following questions: (a) Which planet has rings? (b) Name the planet that has a red spot. (c) What do scientists think of this red spot? (d) Which planet is the windiest? (e) Which planet has craters like the moon? 2. Write each planet’s name and its distance from the sun at the back of each planet picture. 3. Cut out the planets. 4. Start with the sun and place the planets in their correct position, starting with the closest planet to the sun. 5. Display these on the wall of your classroom.

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Teacher Input: Explain to the learners that the sun with its family of planets that move around it is called the solar system. Give learners the task card about the solar system and the planet fact sheet (pages 44–46). Pluto

Saturn Neptune

Mercury

Venus SUN

Earth

Mars

Jupiter Uranus

Learner task

Learner Task Card – The Solar System

Use the planet fact sheet and answer the questions that follow: 1. Label all the planets’ names on the drawing of the sun and its family of planets (solar system). 2. Complete the following A The hottest planet is Venus. A The coldest planet is Pluto. A The biggest planet is Jupiter. A The smallest planet is Pluto. Learner task A The planet which is closest to the sun is Mercury. A The planet furthest from the sun is Pluto. A The planet which takes 365 ¢ days to travel around the sun is Earth. A The planet which takes longest to travel around the sun is Pluto. 3. Now use the information about the distances from the sun to calculate: 90 000 000 km (a) How far away are we from Mercury? (b) how far away are we from Pluto? 5 750 000 000 km (c) how far away is our planet from Mars? 80 000 000

A s se s sm en t Activity

14

5

There are nine planets around the sun

What we want to assess

What we expect from learners

The solar system (row of planets)

a The planets should be placed in their correct order according to their distances from the sun; i.e. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto a Planets’ names should be labeled

The solar system (diagram + questions)

a The planets should be labeled with their correct names on the diagram a Correct interpretation of the planet fact sheet tables, i.e. correct answers to questions 2 a Correct answers for question 3: (a) 90 000 000 km (b) 5 750 000 000 km (c) 80 000 000 km

Activity 6

The inside of the Earth A. The inside of the Earth is made up of layers • Scientists think that the inside of the Earth is made up of four concentric layers (layers arranged around a common centre)

Key concept

Teacher task

Learner task

1. Use the paper model of the Earth made by the learners to remind them about the outside appearance of the Earth. 2. Now find out from the learners what they think the inside of the Earth looks like. 3. Supply each learner with one ‘Astro’ sweet so that learners can begin to imagine what the inside of the Earth is like. 1. Suck an ‘astro’ sweet and find out the following as you suck it: A How does each layer feel? A How many layers does it have? 2. Make a drawing to represent the layers of the ‘Astro’ sweet.

how many layers?

outside sugar coating inside chocolate crunchy inside

Teacher task crust

1. Explain the following to the learners: A Scientists think that the Earth has different layers like the ‘astro’ sweet. A Like the astro, these layers are arranged on top of each other and around a common centre (concentric) 2. Show learners a drawing that shows the inside of the Earth and inform them that a section has been cut out so that we can see what the Earth looks like inside.

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B. A play dough model to show the inside of the Earth • The layers differ in thickness and in composition • The inner core at the very centre of the Earth is the hottest and is solid • The outer core which surrounds the inner core is thought to be molten rock • The mantle which covers the outer core is thought to be plastic (partially melted rock – not completely solid) • The crust which is the outer layer is very thin and solid

Teacher task

Learner task

Give learners the following: 1. A reading about ‘Inside the Earth’ (see page 48). 2. A task card to complete (see page 50). 3. Play dough to make a model of the Earth. 1. Read about the inside of the Earth. 2. Complete the task card about the inside of the Earth.

Learner Task Card – Inside the Earth 1. Read about the different layers inside the Earth and complete the table below. Name of Earth’s layer

INNER CORE

OUTER CORE

MANTLE

CRUST

Thickness in km. (approx.)

1300 km

2250 km

2900 km

8–40 km

Position where found

at the centre of the Earth

around the inner core

above the outer core

outer most layer

look at that!

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2. Use play dough to make the model of the Earth. Use the following colours: red play dough to represent the hot inner core orange play dough to represent the outer core yellow play dough to represent the mantle white play dough to represent the Earth’s crust 3. Cut the model in half with cotton so that you can see inside. 4. Then cut it into quarters. 5. Hold three quarters together. 6. Draw this cut-away section of your model and label the different layers inside Earth.

C. How big is Earth? Teacher task

1. Refer to the drawing of the cut-away section of the Earth’s inside structure (See page ) and explain the following: A The radius is the distance from the centre to the edge A The circumference is the distance around a spherical NOTE TO object TEACHERS 2. Also explain to the learners how to calculate the Learners must have some circumference of a circular object: i.e. circumference background knowledge of what countries and conditions = 2 ∏ r (where ∏ = 22/ 7 and r = radius) are found around the equator 3. Give learners a task card about how big our Earth is to to be able to write an imaginar y journey calculate and complete. (See page xx.)

around the Earth (question 5). They can use their atlase s to see what countries, physical features, seas, forests etc. they wil l come across and they can do a research about these pla ces.

Learner task

1. Calculate the radius of the Earth (its thickness from the centre to the edge)

Radius of Earth = Radius of Earth = Radius of Earth =

thickness of inner core + thickness of outer core + thickness of mantle + thickness of crust 1300km + 2250km + 2900km + 40km 6 490km

2. Calculate the diameter of the Earth

Diameter of Earth = radius x 2 Diameter of Earth = 6490 x 2 Diameter.of Earth = 12 980km 3. Calculate the circumference of the Earth.

Circumference Circumference Circumference

= ∏ x diameter (∏= 22 7) = 12 890 km x 227 = 40 794,285 km

4. Calculate how many days it would take you to walk around the circumference of the Earth. (You will walk along the equator all the way round). Your walking speed is 4km/hour You must walk all day and all night (24 hours). A First calculate the distance you will walk in one whole day (24 hours).

In one hour you walk 4km Therefore in 24 hours you walk 4km x 24 In one day (24 hours) you walk = 96km A Then calculate how many days will it take to walk 40 794,285km

In one day you will walk 96km How many days to walk around the Earth? Days = 40 794,285 km 96 Days = 424,94 days Therefore it will take me 424,94 days to walk around the Earth (a little longer than a year). 17

Learner Task Card (Continued) Imagine that you have to travel around the Earth along the equator. Write to tell about your journey. N.B. You may use your atlas to see what places you will go past and use what you have learnt in Social Sciences about the conditions in the equatorial regions.

Learner task

Around the world in 425 days

I left home on the 22nd of October 1999 for the Democratic Republic of Congo, where I was going to begin my long journey around the world along the equator. As I started this journey I realized that most of my travelling would be through water and tropical rain forests at the equator. I had my coolest clothing with me because the temperature there is very high throughout the year. In the Democratic Republic of Congo (DRC) I had to travel through tropical rain forests. I was stumbling and falling in the thickest plant growth I ever saw. I had to push away the thought of meeting a fierce animal in that thick growth. I was grateful to the small person I made friends with, who helped me to cut and clear my way through the dense thicket with his panga. In the DRC there are small people called pygmies. I wondered why these people were so small. I traveled westwards through to Gabon to cross the Atlantic Ocean to South America. I was there in time to get a lift from one of the yachts (sailing boats) because there was a yacht race in Gabon. Unfortunately the yacht race could not start because there was no wind to set the boats sailing, so I had to use a motorboat to sail across the Atlantic Ocean. I landed in Brazil, where I had to take a canoe and paddle across the Amazon River to get to the bottom of the Andes Mountains. When the river became narrower, I had to abandon the canoe and walk to get to the bottom of the mountain. I had to put on strong shoes to climb around to Ecuador. I could feel the cold air against my skin as I climbed higher and higher up the mountain. At the coast of Ecuador I got onto a boat, which passed the Galapagos Island across the Pacific Ocean to Malaysia. I had to cross the Island of Borneo through the tropical rain forests. This time I used my experience to find my way through this dense forest. I had to sail in a boat again to get to Sumatra and onto another boat to the beautiful Island of Maldives. The long stretch of sunny beach of this island tempted me to stop for a short holiday. It was wonderful to lie back in the sun and think about all the adventures on my journey. By this time I was really feeling home sick and I was ready to finish my long journey around the world. I then took another boat trip back to my home continent, Africa - to the Republic of Somalia. I finally took this last long trip by boat back home. Oh! It was a great feeling to touch the South African soil again. 18

A s se ss m en t Activity

6

The inside of the Earth

What we want to assess

What we expect from learners

The table and questions about the concentric layers of the Earth

A Correct completion of the table, i. e – there should be correct information about each layer – the crust is the thinnest layer – the inner core is the hottest layer

The play dough model of the Earth

A the model should be spherical A layers should be concentric, with the inner core as the inner most layer, followed by the outer core, the mantle and the thin crust as the outer most layer of the Earth

Drawing of the cut-away section of the inside structure of the Earth

The drawing should: A be clear and show all the layers more or less in their correct thicknesses A be correctly labelled A show that it is a cut-away section A have a suitable heading

How big is the Earth?

A correct calculations i.e. (taking 40 km as the thickness of the Earth’s crust) – radius = 6 490km – diameter = 12 980km – circumference = 40 794,28km – 424,94 days

Writing about the journey around the Earth along the equator

The writing should explain: A preparations for the journey, for example what you will need for the journey A what you expect to experience on the journey, for example, kind of weather, other physical and political features of the Earth, what rivers, mountains, countries and people you would expect to meet on this journey A

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Activity 7

Finding out more about our home planet A. We have volcanoes in our planet

Key concepts

• There are weak spots on the Earth’s thin crust • A volcano erupts through the openings on these weak spots • A volcanic eruption happens when hot lava from molten rock (magma) or volcanic ash just below the Earth’s crust shoots out through an opening called a vent at the crust’s weak spots • This eruption occurs because of the heat and pressure from inside the Earth

Teacher task

1. Revise the previous activity and make sure the learners understand that: A The Earth’s crust is very thin and it has weak spots A It is very hot inside the Earth A The layer underneath the Earth’s crust is molten rock and it is very hot 2. Introduce the lesson about volcanoes by setting up the apparatus to demonstrate a volcano as shown in the diagram.

NOTE TO TEACHER … tle. Fill it Use a small glass pill bot and then up to the top with water ea press the cork in well. Us that tissue to mop up any water n begin comes out of the hole. The water in to heat the water. As the l, the pill bottle begins to boi and pressure in the bottle rises bble bu to in water and steam beg o. out of the hole like a volcan

Demonstration to show how a volcano works Cork stopper with a hole Water level Small glass pill bottle Wire gauze Tripod stand

Spirit burner

3. Ask the questions below as the learners observe what is happening: (a) What is happening to the water? (b) What comes through the opening? (c) Why does this happen?

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looks like the principal is erupting again!

4. Discuss answers to these questions introducing terms like: A heating, boiling, pressure, eruption, erupting now and again, steam 5. Ask the learners if they know of any real situation where some of these processes take place. 6. Show learners the picture of Mount St. Helens (page 52). 7. Now read and discuss the volcanic eruption of Mount St. Helens while the learners follow in their own copies (pages 52–56). 8. Show the learners where Mount St. Helens is on the world map (or on their paper models of the Earth).

Mt St. Helens

Learner task

Read and participate in a class discussion about the volcanic eruption of Mount St. Helens.

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Teacher task

Teachers’ copy

Inside a volcano Steam, ash and lava Main vent

Crater

Side vent Cone

Earth’s crust

Hot lava

Very hot molten (melted) rock

Heat from the centre of the Earth

1. Explain how a volcanic eruption happens using the big diagram of a volcano (page 58), and introduce terms like vent at the Earth’s weak spots on the crust, molten rock (magma), hot lava, cone, volcanic ash etc. 2. Give learners a task card “Comparing a demonstration of a volcano and a real volcano” (see page 59). 3. Learners can read about other volcanoes on page 57.

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Learner task

Learner task card Comparing a demonstration of a volcano and a real volcano

Cork stopper with a hole Water level

Main vent

Small glass bottle

Side vent

Steam, ash and lava Crater

Cone

Gauze Tripod stand Earth’s crust

Hot lava

Spirit burner Very hot molten (melted) rock

Heat from the centre of the Earth

1. Label the diagrams and complete the table below. Questions

Demonstration volcano

Real volcano

Where does the heat come from?

flame hot water and steam heat

centre of the Earth steam, ash, & hot lava heat and pressure

What erupts out of the hole / vent? What causes this eruption?

2. Write to tell what happens in a real volcanic eruption.

Volcanic eruption Today we learnt about volcanic eruptions.

there are weak spots known as vents on the Earth’s thin crust through which volcanoes erupt. I also learnt that heat and pressure cause hot lava known as magma from molten rock to shoot out through these vents from just below the Earth’s crust. The other thing I learnt was people live near volcanoes because the soil becomes rich with minerals and they can grow their crops. Finally I learnt that volcanoes can erupt at any time, some are waiting to erupt whereas others are dead. I learnt that

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Learner task

NOTE TO TEACHERS Learners can use the readings about any other volcanoes for their project (see pages xx) or they can use the library for others.

Learner task card – Project 1. Do some research about any volcano that once erupted in any part of the world. 2. In this research write sentences to say: (a) Where and when the volcano erupted (b) What its visible effects were (c) Find out if there are any good things about that volcano. Write sentences about each aspect of the volcano on one page. 3. Make your own booklet about the volcano you researched by clipping (or sticking) your sentence pages together. Do not forget to write your name and an index. Ideas for the booklet: Photograph of the volcano, world map with the place highlighted, details of the volcano written in full sentences with pictures where applicable.

A s se ss m en t Activity

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7

A. We have volcanoes in our planet

What we want to assess

What we expect from learners

Diagrams and writing:

Comparing a demonstration of a volcano with a real volcano a Diagrams should be correctly labeled a The table should be properly completed i.e. table should show a clear understanding of what happens in a demonstration of a volcano and a real volcano

Writing about what happens in a real volcano

a Writing should indicate that the learner understands a volcanic eruption, i.e. heat and pressure continuously push up the hot lava from the molten rock (magma). A volcanic eruption happens when hot lava escapes through the vent on the weaker spots of the Earth’s crust.

Project: Readings and writing of sentences about volcanoes Producing a zigzag booklet on a volcano

The learners should show that they understand the readings by: a Indicating the country where the volcano erupted correctly labeled on the paper model of the Earth a Writing some good sentences with information about each group’s volcano a Producing an attractive and informative zigzag booklet on their volcano a Etc.

B. We need minerals from the Earth’s crust in our lives •

Minerals used for making useful things such as watches and pieces of jewellery come from the crust of the Earth Minerals that are good for our bodies come from rocks and soil that are on the Earth’s crust

•

Teacher task

Learner task

1. Introduce the term mineral. A mineral is a natural substance from which rocks are made. 2. Explain that the Earth’s crust is made of rocks and soil which contain minerals such as gold, diamond, clay, salt, silver etc. 3. Give learners copies of pages 62 and 63 to complete and the Mineral Fact Sheet on page 64.

Learner Task Card So many things come from the Earth’s thin crust

1. Look at the picture of ‘King Arthur’ and think of all the minerals that are useful to him that come from the Earth’s thin crust. 2. Now read the mineral fact sheet and answer the questions about each mineral in the spaces on page 62–63. 3. Write five sentences to tell why the Earth’s crust and its minerals are important to us. I found out that minerals come from the Earth’s crust .......................................................... .......................................................... .......................................................... .......................................................... ..........................................................

A s se ss m en t Activity

7

B. We need minerals from the Earth’s crust

What we want to assess

What we expect from learners

Completing a table about minerals

a

Writing sentences about minerals

Sentences should say: a what the mineral is a where the mineral comes from a why we need that particular mineral a

Should have correct information about where the mineral comes from

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EARTH & BEYOND: GRADE 7 SUGGESTED WORKSCHEME

PERIOD 1 Activity 1 • Choosing a shape which best resembles the shape of the Earth and explanation about own choice • Making of the Earth paper model (±50 min)

PERIOD 2 Activity 2 • Putting of continents and colouring in • Discussion about Earth being mostly covered by water (±50 min)

PERIOD 3 Activity 3 • Reading and answering questions about the gases that form the air (±50 min)

PERIOD 4 • Looking at the layers of the atmosphere and answering questions about them (±50 min)

PERIOD 5 • Reading about how precious air is and how we pollute it • Answering questions and writing a praise poem about air (±50 min)

PERIOD 6 Activity 4 • Looking at the physical features of the Earth (±15 min) • Reading about and comparing planet Earth and the sun (± 35 min)

PERIOD 7 Activity 5 • Reading about nine planets and sequencing them (± 50 min)

PERIOD 8 • Interpreting a table about the planets in the solar system (±50 min)

PERIOD 9 Activity 6a • Revising Earth’s outside features and starting to think about the inside structure (Astro sweet activity) (±50 min)

PERIOD 10 Activity 6b • Looking at the Earth’s inside structure diagram • Reading about it and completing a table (±50 min)

PERIOD 11 Activity 6b (cont) • Making the play dough model of the Earth • Drawing the cut-away section of the model (±50 min)

PERIOD 12 Activity 6c • Explanation of terminology related to measurement of circles • Learners doing calculations and writing about their imaginary journey around the Earth along the equator (±50 min)

PERIOD 13 Activity 7 • Demonstration of a volcano with learners observing and answering questions • Introduction of terminology to do with a volcanic eruption (±50 min)

PERIOD 14 • Reading and discussing about the Mount St. Helens volcano (±50 min) PERIOD 15 • Explanation of how a real volcano happens • Completion of a task card comparing a demonstration of a volcano and a real volcano (±50 min)

PERIOD 16 • Writing about what happens in a real volcanic situation (±50 min) PERIOD 17 • Project: A brief research about a volcano and showing learners how to make their own zigzag books (±50 min)

PERIOD 18 • Learners complete their writing and make their zigzag books. (±50 min) PERIOD 19 Activity 7b • Introducing minerals • Completing a task card about minerals (±50 min)

Total time to finish the activities in this learning programme = 19 PERIODS @ 50 minutes per period = 950 min = close to 16 hours. This is about 4 weeks of work. (Recommended time per week for the Natural Sciences is 4 hours)

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Activity 3a – Reading The Earth’s atmosphere is a mixture of gases

all these gases are mixed together

The air we breathe is a mixture of gases that surround the Earth in layers. Air keeps the Earth’s surface at just the right temperature to support life. These layers of air and other gases are also called the Earth’s atmosphere. 20% oxygen

1% argon and other rare gases less than 1% carbon dioxide

78% nitrogen

that’s what we breathe! The air we breathe also contains the following: A Water vapour A Fumes called hydrocarbons, which come from car exhausts, factories and fires A Dust particles A Other gases, in very small amounts; for example ozone, argon, neon, helium and krypton

Air and living creatures and plants A A

A

We cannot see or taste air. We can detect changes in air temperature on e our skins. We can feel the air moving can’t se I around us. xygen or O y n a We can hear air moving as wind. …

Without air there would be no life on Earth. People can survive for about a month without food, and a few days without water but we cannot survive without air for more than a few minutes. All living things need air. All animals as well as plants ‘breathe’ and use oxygen and give off carbon dioxide to stay alive.

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Nitrogen

Graph paper

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Activity 3a – Air and living creatures Why do we breathe air? When we breathe in, air goes into our lungs. The oxygen in the air goes into the blood vessels surrounding our lungs. The oxygen is carried by the blood to every cell in our bodies. Here the oxygen is used to break down the food in the cells, and release the energy stored in food. We need the energy to move, think, breathe, work and play. After the energy has been released, carbon dioxide gas is given off and carried by the blood back to the lungs. The carbon dioxide is released into the lungs where it mixes with air and is breathed out. All animals and plants use oxygen and give off carbon dioxide in order to produce the energy for them to grow and develop. However, plants also use carbon dioxide from the air to make food. Plants take carbon dioxide from the air and water from the soil and energy from the sunlight to make food. This process is called photosynthesis. Photosynthesis means ‘making with light’. The food that plants make is called starch. When we eat foods containing starch such as mealie-pap or potatoes, this starch was made by the mealie plant and the potato plant. During photosynthesis plants give out oxygen into the air. Read about air and the living things and discuss the following questions in your groups. 1. Why is oxygen important for all living things? 2. How is oxygen carried to every cell in our bodies? 3. What do plants use carbon dioxide for? 4. Where do plants get carbon dioxide from?

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Activity 3b – Layers of the atmosphere

IONOSPHERE This layer absorbs dangerous rays from the sun. Radio waves coming from Earth reach this layer and are bounced back to a different part of the Earth where they are picked up by peoples’ TVs and radios. This is how radio programmes are transmitted around the world.

MESOSPHERE This layer is very cold (–100°C). It protects the Earth from rocks (meteors) and dust that fly into the atmosphere from space.

STRATOSPHERE This layer is like a shield. It protects the Earth and living things from the sun’s dangerous rays.

TROPOSPHERE This layer has all the air that we need for breathing. All animals and plants live in this layer. This layer has water vapour and clouds and this is where we find different kinds of weather. The gases making up the Earth’s atmosphere become less and less the further you go away from the Earth until there is no atmosphere at all in space. Half of the atmosphere is below here The gases making up the Earth’s atmosphere become less the further you go away from the Earth until there is no atmosphere in space.

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Activity 3c What pollutes the air? The air is precious The Earth’s air is the only air that we have. It is the same air that our ancestors breathed. It is the same air that the dinosaurs once breathed. We breathe the same air that our dogs and cats breathe. The air we breathe is the same air that has passed through our motor car engines and factory chimneys and the plants outside. The same air is used over and over again because it is the only air that we have. We can’t get any more air from anywhere else. When we make the air dirty from engines and factories, we call this polluting the air.

WHAT POLLUTES OUR AIR?

This picture shows all the different things that pollute the air. The polluted air is used again and again. Air pollution We say that the air is polluted when it becomes dirty. Substances that make the air dirty are produced in many different ways: A When we burn fossil fuels (coal and oil) in power stations to make electricity A When we make things that require burning and heating in factories A When we drive motor cars which always give off fumes A When we burn rubbish and motor car tyres A When we burn grass, bushveld and trees. Strong sunlight interacts with the exhaust fumes from motor vehicles and this can produce poisonous gases. Sometimes we can see and smell these gases. They have a brownish colour and we call this smog. Smog is dangerous to plants and animals.

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Activity 4 – Reading The Earth is a planet The Earth is a planet. It is shaped like a ball and it moves through space around the sun on its own pathway known as the orbit. It gets its heat and light from the sun. It is the only planet that has life as far as we know. It is made up of rock whereas other planets are made up of rock and gas.

The Earth

The sun

The sun is a star The sun is a star and not a planet. It is a huge ball of very hot gases. It gives off light and heat. It is the closest star to planet Earth. We get heat and light from our local star, which is the sun. It is more than hundred times bigger than the Earth. The sun has nine planets including the Earth that move around it in space.

Learner Task – Activity 4 1. Complete the following table to compare our Earth and the sun. Questions

EARTH

SUN

1. Is it a planet or a star? 2. What is it made of? 3. Does it give out light and heat? 4. Which is bigger, the Earth or the sun? 5. Can life survive on it? 2. Write sentences to compare the differences between planet Earth and the sun. (Use the table to help you.) ......................................................... ......................................................... ......................................................... .........................................................

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The nine planets in our solar system

All pictures courtesy NASA

The four Galilean moons

Jupiter Diameter

142 800 km

Mass

318 Earth masses

Distance from the sun

800 million km

Number of moons

16

Rotation period

length of day in Earth hours 9.8

Time to go round the sun

length of year in Earth years 11.9

Jupiter is the largest of the gas giants. The white clouds that we see are at a temperature of –153° C and consist of ammonia ice crystals. Lower down, the clouds are coloured red and brown by organic compounds and chemicals such as sulphur. Winds speeds of over 400 km/h are common; the Great Red Spot is thought to be a long-lived hurricane and is larger than Earth. Jupiter probably has a rock or ice core surrounded by liquid hydrogen with helium dissolved in it.

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Jupiter has 16 known moons, but four are larger than the rest and can be seen easily with binoculars. They are known as the “Galilean moons” after their discoverer Galileo.

Earth Our Home Planet Diameter

12 750 km

Distance from sun

150 million km

Rotation period

length of day in Earth hours

23.93 Time to go round the sun 365.24

length of year in Earth days

Uranus

Mercury

Diameter

51 118 km

Mass

14.5 Earth masses

Distance from the sun

3000 million km

Diameter

4 878 km

Number of moons

15

Mass

0.06 Earth masses

Rotation period

Distance from Sun

60 million km

length of day in Earth hours 17.9

Number of moons

none

Rotation period

length of day in Earth days 58.7

Time to go round the sun

length of year in Earth days 88

At the equator it is hot enough to melt lead. At the poles there are craters with ice frozen to –150 °C. Mercury has no atmosphere.

Time to go round the sun length of year in Earth years 84 Uranus shows an almost featureless green ‘surface’ of clouds floating in a cold (–197°C) atmosphere of hydrogen, helium and methane. Beneath the clouds, most of Uranus (85%) is ice.

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Venus Diameter

12 104 km

Mass

0.8 Earth masses

Distance from Sun

104 million km

Number of moons

none

Rotation period

length of day in Earth days 243

Time to go round the sun length of year in Earth days 225 Venus is a hot and hostile planet. An atmosphere of carbon dioxide 90 times as dense as Earth’s keeps the surface hot enough to melt lead. Clouds of sulphuric acid hide its surface.

Saturn Like Jupiter, Saturn is a gas giant consisting mainly of hydrogen and helium. Its famous ring in fact consists of thousands of narrow rings made up of lumps of ice and rock as small as dust grains and as large as a minibus.

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Diameter Mass Distance from Sun Number of moons Rotation period Time to go round the sun

120 660 km 95 Earth masses 1 400 million km 18 length of day in Earth hours 10.2 length of year in Earth years 29.5

Mars Diameter Mass Distance from Sun Number of moons Rotation period Time to go round the sun

6 787 km 0.1 Earth masses 240 million km Two. Phobos and Deimos length of day in Earth hours 24.62 length of year in Earth days 687

The atmosphere of Mars is 100 times less dense than Earth’s and consists mainly of carbon dioxide, with traces of water vapour. In winter temperatures drop to –125 °C, giving Mars its well known white ‘ice caps’. In summer equatorial temperatures can reach 20 °C. The planet’s reddish colour is caused by iron in the soil. Bacterial life forms may once have existed on Mars.

Neptune Diameter

49 528 km

Mass

17 Earth masses

Distance from sun

4 500 million km

Number of moons

8

Rotation period hours 19.1

length of day in Earth

Time to go round the sun years 164.8

length of year in Earth

Neptune is another ‘ice giant’ like Uranus and even colder (–225°C). Its bluish atmosphere of hydrogen and helium shows occasional large dark spots, and is probably the windiest place in the solar system with storm winds reaching speeds of 1400 km/h.

Pluto Diameter 2 300 km Mass 0.0025 Earth masses Distance from sun 4 400–7 400 million km Number of moons 1 Rotation period length of day in Earth days 6.4 Time to go round the sun length of year in Earth years 247.7 Pluto is smallest of the planets, and usually the remotest and coldest. At –233°C, frost of methane and nitrogen coat the pinkish surface. Pluto’s grayish moon, Charon, is only 19 400 km away, and more than half Pluto’s diameter.

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The Solar System

40

SUN

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The Planets fact sheet

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PLANET

Distance from the sun in km

Size of planet Number (diameter in km) of moons

Mercury

60 000 000 km

5 000 km

0

It looks like our moon

Venus

104 000 000 km

12 000 km

0

It is the brightest planet

Earth

150 000 000 km

13 000 km

1

It is the only planet known to have life on it

Mars

240 000 000 km

7 000 km

2

It is known as the red planet

Jupiter

800 000 000 km

143 000 km

16

It has a red spot and striped appearance

Saturn

1 400 000 000 km

120 000 km

18

It has a set of rings around it

Uranus

3 000 000 000 km

52 000 km

15

It looks green. Most of it is ice.

Neptune

4 500 000 000 km

8

It appears blue

Pluto

5 900 000 000 km

1

Very little is known about this planet

50 000 km

2 000 km

Other features

Learner Task Card – Activity 5 The Solar System Use the Planets fact sheet and answer the questions that follow: The solar system

1. Label all the planets’ names on the drawing of the sun and its family of planets (solar system) 2. Complete the following

• The hottest planet is . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • The coldest planet is . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • The biggest planet is . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • The smallest planet is . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • The planet which is closest to the sun is . . . . . . . . . . . . . . . . . . . . . • The planet furthest from the sun is . . . . . . . . . . . . . . . . . . . . . . . . . . • The planet which takes 365 ¢ days to travel around the sun is ......................................................

• The planet which takes longest to travel around the sun is ...................................................... 3. Now use the information about the distances from the sun to calculate: (a) How far away are we from Mercury . . . . . . . . . . . . . . . . . . . .km. (b) How far away are we from Pluto . . . . . . . . . . . . . . . . . . . . . .km (c) How far away is our planet from Mars . . . . . . . . . . . . . . . . . .km

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Activity 6 B. Inside the Earth

crust

The Earth’s Inner Core The inner core is at the very centre of the Earth. This is a very dense layer made of metals such as iron and nickel. The temperature of the inner core reaches about 5 000°C. Iron and Nickel will usually melt at this temperature, but the enormous pressure from the layers above pushes the particles of iron and nickel so tightly together that they remain solid. The iron in the inner core may explain why there is a magnetic field around the Earth. Scientists think that the iron produces an effect similar to the magnetic field around a magnet. The thickness (radius) from the centre of the inner core to its edge is about 1 300 kilometers (km). The inner core is about 5 150 km below the Earth’s surface. The Earth’s Outer Core The outer core surrounds the inner core. The outer core is also made of iron and nickel. This layer is also very hot. The temperature in the upper part is about 2 200° C but near to the inner core, the temperature is almost 5 000°C. This tremendous heat makes the iron and nickel in the outer core melt. We say it is molten. This means it is like a very hot liquid.

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The outer core is about 2 250 km thick and it is about 2 900 km below the Earth surface. The Earth’s Mantle The mantle is the layer of the Earth that lies above the outer core. Most of the Earth is made up of the mantle (about 80%). The Earth’s mantle is made of some solid and some melted rock (magma) mixed together. The mantle is slightly soft and runny because it is hot. We say that it is ‘plastic’ because it can bend to change its shape. This does not mean it is plastic but it can behave like plastic. The mantle is about 2 900 km thick. The Earth’s Crust The Earth’s crust is the thin outer layer of the Earth. All living things are found on the Earth’s crust or just below and above it. The crust is solid. It is not ‘plastic’ or molten like the other layers. The crust is made of three types of solid rocks: igneous, sedimentary and metamorphic rocks. These rocks contain mostly oxygen and silicon (sand). Other common minerals found in the Earth’s crust are aluminium, iron, calcium, sodium, potassium and magnesium. We also get precious metals such as gold in the crust. The crust is thin, like the peel on an apple. It is much thinner than the other layers of the Earth. Its average thickness is only about 8 km. The part of the crust beneath the oceans, called oceanic crust, is also thin (less than 10 km). Oceanic crust is made mostly of silicon, oxygen, iron and magnesium. The crust beneath the continents, called continental crust, is about 32 km thick. Beneath the mountains, continental crust is even thicker than 32 km.

RECIPE for PLAYDOUGH INGREDIENTS: 1 cup flour 1 cup water 1 tablespoon oil 1 teaspoon cream of tartar 1 teaspoon food colouring

™ cup salt

METHOD: 1. Put all the ingredients together in a pot 2. Cook the mixture on moderate heat until it goes thick like porridge (about 3 minutes) 3. Wait for the mixture to cool off and roll it into a ball (Put some flour on your hands first) 4. Store your dough in a plastic bag in the fridge N.B. for making the play dough model of the Earth you will need four different colours. 1. Plain white dough (no food colouring) for the crust 2. Yellow dough (add yellow food colouring) for the mantle - so you need a lot 3. Orange dough (mix red and yellow food colouring) for the outer-core 4. Red dough (add red food colouring) for the inner-core.

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Learner Task Card – Activity 6 B. Inside the Earth 1. Read about the different layers of the Earth and complete the table below. Name of Earth’s layer

INNER CORE

OUTER CORE

MANTLE

CRUST

Thickness in km.(approx.) Position where found 2. Use play dough to make a model of the Earth. N.B. Use the following colours red play dough to represent the hot inner core orange play dough to represent the outer core yellow play dough to represent the mantle white play dough to represent the Earth’s crust 3. Cut the model in half with cotton so that you can see inside. 4. Then cut it into quarters. 5. Hold three quarters together. 6. Draw this cut-away section of your model and label the different layers inside Earth.

Use red play dough to represent the hot inner core. Cover it with orange play dough to represent the outer core.

Wrap yellow play dough around to represent the mantel.

Put on the final layer of white play dough to represent the crust.

Cut the model in half with a piece of cotton

This is what you get … 46

Learner task card – Activity 6 C. How big is our Earth? 1. Calculate the radius of the Earth. (Its thickness from the centre to the edge.) . . . . . . . . . . . . . ................................................................................. 2. Calculate the diameter of the Earth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Calculate the circumference of the Earth: circumference = ∏ x diameter (∏ = 22 ). 7

............................................................................ ............................................................................ ............................................................................ 4. Calculate how many days it would take you to walk around the circumference of the Earth (you will walk along the equator all the way round). Your walking speed is 4km/hours. You must walk all day and all night (24 hours). ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. .................................................................................

Writing task Activity 6 – How big is our Earth? Imagine that you have to travel around the Earth along the equator write to tell about your journey. N.B. You may use your atlas to see what places you will go past and use what you have learnt in Social Sciences about the conditions in the equatorial regions. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. ................................................................................. .................................................................................

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WAITING FOR THE ERUPTION Mount St Helens, Seattle, USA

ount St. Helens was like a time bomb, ticking away towards “self-destruction”. Seven weeks before the eruption, the world heard that the mountain was a danger because ash and steam began to pour out of the top of it. Mount St Helens is usually covered with layers of ice and snow. It is in southwestern Washington in America. This is a beautiful land of deep forests, rushing streams, rich farmlands and nearby cities. The people waited anxiously as they experienced small eruptions and earthquakes from Mount St Helens. Days and weeks passed without disaster and people began to relax. Every now and then the volcano shook the ground and the steam and ash appeared. But many people thought that the mountain seemed to be calming down. Then they noticed that its north side began to bulge and grow bigger.

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The eruption starts “This is it …” With those excited words, David Johnston, a geologist for the United States Geological Survey, announced the end of calm and the start of disaster. David was thirty years old and blond and bearded. He was six miles from Mount St Helens at a scientific station on the side of another mountain. He was studying Mount St Helens and watching for any changes and eruptions. Those words were his last. The eruption he

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reported was powerful and came out of the side of the mountain. Red-hot rocks and steaming gases travelling at 400km an hour, blasted out of the mountain. It swept him and his research station off the side of the mountain to his death. His body has yet to be found. What happened during the eruption – Sunday, 18 May 1980 In the first seconds of the eruption the side of Mount St Helens collapsed. This caused waves of ice to tumble down into the hot ash. Quickly the 18,4 billion kilograms of ice melted, and about 46 billion litres of water created a mud and water flood. It caused a disaster, sending mud, ash, broken trees and rocks down the South Toutle River Valley, for 30 km. Like a monster, the flood destroyed the river, roads, trees, trucks, a few cars and caravans. As the flood swept on, a million tree logs tumbled on the crest of the wave. WHAT PEOPLE SAW AND EXPERIENCED Eye-witness 1 “There’s no way, there’s just no way anyone could be alive up there.” The camp is covered by more than a metre of ash. The only sign of the camp is the top of a car. It’s full of ash. The windows are blown in. I tried to blow the ash away but it boiled up. The ash was still very hot. “That’s where the

village was!” There was no sign of the homes, no sign of a tree, a road, or anything familiar. We saw 30-metre tall cranes fallen and twisted, bulldozers overturned, trucks buried or wrecked. Here and there we saw a car or bakkie with its windows shattered. Were there victims inside? Here a body lies by a station wagon’s open door, there is another in the back of a truck. Mud had also buried miles of the South Toutle River Valley, and floods had passed through, tossing acres of huge logs into chaos and wrecking a train. An avalanche (mass of snow) swept thousands

of trees and other debris into the lake, which, along with water from the melting ice raised its water level by about 60 metres. Eye-witness 2 They were flying in a small aeroplane directly over the mountain at 8:32 a.m. on May 18. “We arrived at 7:50 in the morning and flew twice directly over the crater (the opening in the top of the mountain) and several times around the mountain,” Dorothy said. “The thing that impressed us was that it didn’t look like an active volcano – more like one going to sleep.” Then they saw a frightening sight: “We were

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making a final flight over the crater when Keith started to see ice sliding off the mountain. Suddenly, the whole north half of the mountain began to slide away, directly beneath us! I went into shock. Keith took pictures while steam started to come out from under the snow.” Then he ran out of film. “That’s what saved our lives, because then Keith glanced over his shoulder and saw the sideways blast starting and recognised the danger of our situation. He told the pilot, Bruce Judson, that we had to get out of there. “Bruce accelerated the plane. Ash began to explode out of the mountain forming a huge cloud but we feared the ash cloud was going to catch up with us. We were travelling east and so was the cloud. Then we could see lightning in the cloud. Keith was afraid the lightning would strike the plane. The pilot turned south and dived to gain speed.” Though the frightening cloud was like an umbrella overhead, they finally escaped. “It took me a month to learn to relax,” Dorothy said. Her mind plays and replays the thought that If they had stayed a few seconds more, that little aeroplane would have flipped and fallen like a burned grasshopper, and they would have died. “I felt a growing fear for all of us living on a planet, whose crust is so thin and fragile, on top of such terrible heat and pressure. Never again, would I feel safe about this world we live on.” Eye-witness 3 “There was no sound to it, not a sound – it was like a silent movie, and we were all in it. First the ash cloud shot out to the east, then to the west, then some lighter cloud started shooting straight up. At the same time the ash started coming right down towards us. I could see boulders – they must have been huge – being hurled out of the mountain. “In frantic haste that seemed in slow motion, we scurried into six trucks and dashed toward safety over mountain roads. We were the lucky ones. Only the day before, we had been working on the northeast side of the mountain, now a dead gray hell.” Some 35km away, a group of four men cutting trees was caught by the blast. They tried to walk out, their scorched clothing sticking to their burned skin. One man climbed a tree to escape the fiery blanket of ash, and his body was found

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there weeks later. After eight hours a helicopter rescued the other three, two of whom died in a hospital. Eye-witness 4. “This black, black cloud, of a blackness like I had never seen, came over, and of course we thought it was going to be a tremendous rainstorm. Then we could see little drops on the lake, and we looked at our coats and saw we weren’t getting wet. Then it all occurred to us that it had to be an eruption of Mount St. Helens. So we dashed for camp, but by the time we started packing we had to use torches. The only way we could see to drive was to look for the edge of the road – all the time hoping no one was stopped in front of us.” Eye-witness 5 A death toll of hundreds – even thousands – seemed likely that Sunday, May 18, as the mountain erupted inside out. The ash swept darkly over the beautiful Yakima Valley, across fields of wheat around Moses Lake and a town called Ritzville and settled on other cities. Cars, trucks, buses, trains and planes stopped. People coming out of church, prayed on their way home. Service stations, restaurants and shops closed. The ash caused the electricity to fail. Thousands of people travelling on the roads tried to find shelter in hotels, schools and homes. You could see nothing ahead of you, even with the car headlights. In the town of Yakima, midnight seemed to arrive at 9:30 in the morning and street lamps burned all day. In memory it has become Black Sunday. The ash was composed of fine volcanic glass particles; the cloud was itself a mass of sharp glass. Insects died as their bodies dried out in the heat. Some small creatures quickly choked. Some birds lost their way and could not see and fell to the ground. Larger animals were almost suffocated and behaved strangely. Cattle and deer and elk (a large buck with horns) wandered around in a daze.

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He refused to leave

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Life and Mount St. Helens were one and the same for Harry Truman, 84. For more than half a century he had lived beneath the snow crowned peak, where he built a guest lodge beside Spirit Lake. Harry refused to flee last March when the volcano, only five miles away, awakened: “If I got out of here, I wouldn’t live a day, not a day.” “I talk to the mountain, the mountain talks to me. I am part of that mountain, the mountain is part of me.” On May 18 St. Helens buried the lodge under hundreds of feet of ash and debris and the raised waters of Spirit Lake, and Harry’s words became reality.

There have been others … VESUVIUS Volcanic eruption, Italy, AD 79 In the year 79 AD three Roman towns, Stabiae, Herculaneum and Pompeii were destroyed when a volcano in mount Vesuvius erupted. The towns situated around the bay of Naples, were buried under tons of volcanic ash. Pompeii was a successful market town and a port that traded in the products of the farms in the area. The farmland was fertile because of the presence of mineral-rich ash from the previous eruptions of Mount Vesuvius, which had been inactive for hundreds of years. Many of the residents of Herculaneum were burned alive by the hot ash and gas. These were followed by dense flows of light rock called pumice and ash which entombed (buried) the people who lived there.

HEIMAEY Volcanic eruption, Iceland, 1973 On 23 January 1973 the ground split open on the island of Heimaey in Iceland. Lava began to shoot out 150 metres into the air. The people who were living there quickly made their way to the harbour and were taken to a place of safety. On the night of the eruption, a wall of flaming lava roared into the air on the outskirts of the town. Houses burst into flames as streams of glowing lava swallowed them. People were not able to save their homes or the island from being swallowed by the lava and the ash. The eruption lasted for five months. When it finally stopped, two km long lava flow had swallowed a large section of the island. Fortunately only one life was lost, but 1 200 homes had been destroyed.

MONT PELE’E Volcanic eruption, Martinique, West Indies 1902 In 1902, St. Pierre was the largest town on the tiny French island of Martinique which was home to about 30 000 inhabitants. The people who lived here were used to the rumbling noise of Mont Pele’e, which was 1,379 metres high and was located less than 8 kilometres away.

Mount Pele’e has been giving out gas since 1889, but in April 1902 the volcano began erupting. By May, people began to fear danger as clouds of steam and ash poured from the volcano, darkening the sky and covering the streets like a blanket of snow. Many people left St. Pierre after water from a crater was spat out by an eruption. Mud swept away a nearby factory with 23 of the people who worked there. A large black eruption cloud poured down Mont Pele’e and raced through St. Pierre at a terrifying speed. The cloud was hot enough to melt a glass. It happened so suddenly that people had no time to take cover, let alone escape the deadly cloud. Within seconds the cloud had killed all but two of the people of St. Pierre, Ciparis, a prisoner in an underground cell and Leon the shoemaker.

NEVADO DEL RUIZ Volcanic eruption, Colombia, South America 1985 An eruption of the remote Nevado del Ruiz volcano on 13 November 1985 caused the second deadliest volcanic tragedy of the twentieth century. The heat of the ash and the gases released during the eruption melted a large section of the mountain’s ice cap. The water from the melting ice poured down the mountain, carrying tons of sticky mud. This mud flowed down a river valley near the town of Armero, sending a 40 metre high wave of mud towards the town. Around 21 000 people were killed by the mud, along with over 1000 others in the neighbouring villages. The ash from the past eruptions enriched the soils in the central parts of Colombia, creating excellent farm land. Armero a town with 23 000 residents, had been located about 50 kilometers from the volcano and had been built up around warehouses that stored rice, cotton and coffee, which was grown in the area.

MOUNT NYIRAGONGO Volcanic eruption, Goma, Democratic Republic of Congo, January 2002 Tens of thousands of people were driven from this large town ahead of streaming lava when Mount Nyiragonga erupted early this year. More than 300

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Heat from the centre of the Earth

Earth’s crust

Side vent

Main vent

Hot lava

Cone

Very hot molten (melted) rock

Crater

Steam, ash and lava

Learner task card – Activity 7 A. Comparing a demonstration of a volcano and a real volcano 1. Label the diagrams and complete the table below.

Questions

Demonstration volcano

Real volcano

Where does the heat come from? What erupts out of the hole / vent? What causes this eruption?

2. Write to tell what happens in a real volcanic eruption.

Volcanic eruption Today we learnt about volcanic eruptions. I learnt that - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --------------------------------------------------------------------------------------------------------------------------------------------------I also learnt that

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--------------------------------------------------------------------------------------------------------------------------------------------------The other thing I learnt was - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --------------------------------------------------------------------------------------------------------------------------------------------------Finally I learnt that - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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Learner Task Card – Activity 7b B. So many things come from the Earth’s thin crust 1. Look at the picture of ‘King Arthur’ and think of all the minerals that are useful to him that come from the Earth’s thin crust.

2. Now read the mineral fact sheet and answer the questions about each mineral in the spaces on page 62–63. 3. Write five sentences to tell why the Earth’s crust and its minerals are important to us. I found out that minerals come from the Earth’s crust

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Activity 7

B. Mineral fact sheet

NAME OF MINERAL

FACTS ABOUT IT

Gold

Comes from deep inside the Earth’s crust. We have to dig deep mines to find it.

Silver

Comes from rocks in the Earth’s crust. We have to dig mines to find it. We have to purify it from the rocks.

Salt

Comes from sea water. Sea water is salty from minerals that have been washed from the land. We have to dry (evaporate) the sea water to get salt.

Diamonds

Come from the Earth’s mantle and they get pushed up to the Earth’s crust during volcanic activities.

Chalk (lime)

Is soft rock from the crust which has formed from many layers of dead sea animals and their shells.

Coal

Is a rock formed from the bodies of dead plants and animals, which were buried under many layers of rocks. We find coal by digging deep mines in certain places in the crust.

Clay

This is a mineral, which we find in soil. We find pure clay in certain parts of the crust. We can make clay pots from it.

Tungsten

This is a metal, which is mined from the crust. We use it to make the wires of light bulbs.

Silicon

Most sand on the surface of the Earth is made of silicon. When we melt it at a very high temperature it becomes glass.

Copper

This is a metal, which we mine from the crust. We use it for making electrical wires.

Iron

This is a metal, which is found in red soils. We have to heat the soil in a hot oven to get the iron out. We use it to make steel to produce nails and screws.

Iron in our bodies

We have iron in our blood. It makes our blood red and carries oxygen. We get iron from eating plants which take up iron from the soil, e.g. green vegetables.

Fluoride

This is a mineral found in water. It gets into water from the soil and the rocks. It is put into toothpaste to make our teeth strong.

Calcium

Comes from soil. We get calcium from animals that eat plants that grow in the soil e.g. in cow’s milk. Calcium makes our bones strong.

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What does ‘king of kwaito’ Arthur Mofekate need?

So many things come from the Earth’s thin crust 1. Look at the picture of ‘King Arthur’ and think of all the minerals that are useful to him that come from the Earth’s thin crust. 2. Now read the mineral fact sheet on page 64 and answer the questions about each mineral in the spaces below. 3. Write about six sentences about minerals from the Earth’s crust. Remember to write a heading. You may begin like this: I found out that we need minerals from the Earth’s crust. I know that minerals are important to me because . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Where did the fluoride in his toothpaste come from?

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Where does this chalk come from?

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Where did the tungsten wires in this light bulb come from?

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Where did the silicon to make glass come from?

His ear ring is made of gold. Where did the gold come from?

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Where do diamonds come from?

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Where did the iron in his food come from?

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He uses salt to make his food tasty. Where did it come from?

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Where did the copper in the wires of these electrical appliances and equipment come from?

Where did the calcium that made his teeth and bones strong come from?

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This cutlery is made of silver. Where did it come from?

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Where did the clay to make this cup come from?

Where did the iron and steel in his car come from?

Where does the coal for this fireplace come from?

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