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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

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
Do somebody tell me a best nano engineering book for beginners?
s. Reply
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?
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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
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?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
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 8. OpenStax CNX. Sep 12, 2009 Download for free at http://cnx.org/content/col11050/1.1
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