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Natural sciences

Grade 8


Module 23

Prehistoric life

For millions of years, life on earth consisted of microscopic single cell organisms only. True animals, like jellyfish and sponges, appeared about 700 million years ago.

They had soft bodies, but the development of shells, teeth and claws has made it possible for us to determine their appearance. How do we do this? By studying newly discovered fossils.

Finds of fossils dating from after the Cambrian period include animals like crocodiles and sharks.

Some animals quickly became extinct when conditions changed. Others were able to adapt and survive. Massive extinctions have occurred at various times in the history of the earth.

The age of the earth is counted in billions of years.

Find out more about this: Visit www.ucamp.berkeley.edu/exhibit/geology.html

Like clock time that is divided into hours, minutes and seconds, the history of the earth can be divided into four large “blocks”. We refer to these as AEONS. The first three aeons together are known as the Precambrian period. Our information about this period is scant because few fossils have survived to be studied.

The last period is known as the Proterozoic aeon. This aeon commenced approximately 540 million years ago and is divided into four eras.

The eras are divided into periods that might have lasted for 2 to 80 million years each.

Activity: to do research and to collect data

1. Explain what you understand by geological time:

2. Use the circle to illustrate geological time as described above.

3. What would have caused the massive extinctions referred to in the above passage?

4. Explain what fossils are.

5. How do you think scientists determine the age of the earth? Find out about carbon dating.

Research: carbon dating

6. Find out about EVOLUTION as documented.

  • Bear in mind that this is a sensitive topic and that not all people hold the same opinions. The scientist, however, has a duty to examine all phenomena and theories and to share his / her deductions with other people. Each individual can then decide whether he or she agrees or not. Make an informed decision!

Research: evolution

  • Search in google.com

Assessment of RESEARCH:

Could you find any information on carbon dating and evolution?

[ LO 1.2]


Learning outcomes 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 is able to conduct an investigation and collect data.



  • Preparation – read about carbon dating and find sources of information on evolution.
  • As well as mass extinctions.
  • Find appropriate video material.

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
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Source:  OpenStax, Natural sciences grade 8. OpenStax CNX. Sep 12, 2009 Download for free at http://cnx.org/content/col11050/1.1
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