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Natural science

Grade 9

The earth, galaxies and space programmes

Module 13

The earth and its features


  • Inner core - very dense, unbelievably hot
  • Outer core - in a molten state
  • Mantle - molten rock
  • Crust - solid rock (very thin)

Activity: diagram

Draw a circle and draw in these layers . Use different colours to indicate the different layers.

Assessment of diagram:

Did you indicate the layers correctly?

[LO 2.3]

  • The core comprises iron and nickel, and the crust consists of oxygen and silicon.
  • In the soft mantle there are silicates, oxides and sulphates.

why does the earth rotate?

  • The earth rotates because it falls in the direction of the sun. The sun’s force of gravity causes the earth to revolve around sun and rotate on its axis.
  • It is like a ball rolling down a hill.
  • The earth revolves once around its own axis every 24 hours.
  • Each planet in the solar system also revolves around the sun in its own orbit.
  • The earth takes 365¼ days to complete one orbit. This is also called a revolution or, in general terms, a year (‘ earth-year ’).
  • It takes each planet a specific number of earth-years to complete one revolution around the sun.
  • Mars, has a revolution time of 1,9 earth-years.
  • Jupiter takes 11,9 earth-years and Pluto 247,7 earth-years to orbit the sun.

how big is the earth?

split up into groups for the next activity.

Activity: discussion

information on the earth:

Circumference around poles: 40 008 km

Diameter at poles: 12 714 km

Circumference at Equator: 40 075 km

Diameter at Equator: 12 714 km

1. What can you deduce from these statistics regarding the shape of the earth? What could be the explanation for this?

2. Who was Eratosthenes and what did he say 2 000 years ago about the shape of the earth? Discuss this in groups and write down the answers. ( www.union.edu/PUBLIC/GEODEPT/hallocher/sciencelab/Labs/ ND2/LN2.htm)

Assessment of DISCUSSION:

[LO 1.2; LO 1.3]

why is life possible on earth?

  • It is the only planet in our solar system where there is an atmosphere with oxygen and where there is surface water. Life as we know it requires oxygen and water!
  • The oceans take up about 70% of the earth’s surface.
  • The earth’s atmosphere comprises the following gases:
  • oxygen (21%)
  • nitrogen (78%)
  • argon (0.9%)
  • carbon dioxide (0.03%)

Activity: circle diagram

Draw a circle. Use different colours, indicating the composition of the atmosphere in percentages in the circle.

Work out the sectors mathematically.

Assessment of circle diagram:

Is your diagram correct? [LO 2.4]


LO 1: Scientific investigations:

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

This is evident when the learner:

1.2 conducts investigations and collects data;

  • evaluates data and communicates findings.

LO 2: Constructing Science Knowledge:

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

This is evident when the learner:

  • interprets information;

2.4 applies knowledge.


The earth and its features


1. The shape of the earth is not altogether round. It is slightly flattened at the poles because its rotation is faster at the equator

2. A Greek philosopher who was the person to show that the earth is round by means of a calculation.


The atmosphere consists of 21% oxygen, 78% nitrogen and 0.03 % carbon dioxide, and 0.9 % argon

In diagram: atmospheric gases

Questions & Answers

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Akash Reply
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s. Reply
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Devang Reply
are you nano engineer ?
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Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
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so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
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s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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Sanket Reply
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preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
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I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
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Source:  OpenStax, Natural sciences grade 9. OpenStax CNX. Sep 15, 2009 Download for free at http://cnx.org/content/col11069/1.1
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