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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

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 to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
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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