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Natural sciences

Planet earth and the universe

The earth

Educator section


Assignment 1:

  • Assess using the assessment matrix.

Assignment 2:

Main Ideas

  • Earthquake: evening of 29 September 1969.
  • Registers 6.5 on the Richter Scale.
  • Chaos in most places.
  • Rumbling grew louder and louder and was followed by tremendous quake.
  • The whole earth shuddered and people ran about panic stricken.
  • Rescuers used the Post Office as a base because it was the only place which had electricity.
  • Homes were badly damaged and people were badly injured.
  • Emergency aid streamed to the disaster towns and the police and army co-operated.
  • People were housed in tents and field hospitals were erected.
  • The water shortage was alleviated and food was supplied.
  • R13 million donated by the Disaster Committee

Assignment 3:

  • (sketch)

Assignment 4:

1. The Richter Scale is the instrument (scale) which seismologists use to measure the strength of an earthquake.

2. Seismologists are scientists who study earthquakes.

3. The place at which the shock waves first reach the surface of the earth is known as the epicentre.

4. If the pressure in the mantel under the crust builds up then magma is forced through weak places and cracks. These weak places then form volcanic pipes.

5. Active volcanoes are volcanoes which erupt from time to time.

Leaner section


Activity: to analyse the structure of the earth and to measure movements in it (natural disasters) [lo 2.1, lo 2.3]


  • Scientists believe that Earth came into existence about 4 600 million years ago as a large cloud of gas and dust swirling around in space. While it was rotating it shrank to an extremely hot, liquid ball. The surface gradually cooled and a crust of solid rock formed which weathered to the mountains, soil and sand on which we live today.
  • Earth is continually changing. The land masses (continents) are not only moving, but new crust is forming all the time. The movement of the crust is called continental drift and it is still occurring. America, for example, is moving gradually away from Europe. This movement has already led to telephone cables under the Atlantic breaking.


  • The Crust

The crust is the outermost layer and has a thickness of from 5 km to 70 km. Under the oceans the crust can be as thin as 5 km and where there are mountains the crust can be as thick as 70 km. Beneath the crust there are three other layers. They are:

  • The Mantle

The mantle is 2 900 km thick. It is solid but contains slowly flowing currents of semi-melted metals.

  • The outer Core

The outer core consists of liquid metal and is responsible for the earth’s magnetic field. It is 2 240 km thick.

  • The inner Core

The inner core in the middle of the earth is probably solid and consists mainly of metals. The temperature is 3 700 degrees Celsius. Water boils at 100 degrees Celsius. The inner core has a diameter of 2 240 km.

The lava that flows from volcanoes comes from the mantle.


Use playing dough (four different colours) to make a model of Earth’s structure. The thickness of each layer should be more or less proportional to the actual thickness of the earth’s layer.

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 7. OpenStax CNX. Sep 16, 2009 Download for free at http://cnx.org/content/col11077/1.1
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