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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

what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit 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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