人教高中英语必修3Unit4Reading （共25张PPT）

(共25张PPT)
Part One:Lead in
What is this?
Which planet is its home?
This is ChangJiang7.It is an alien（外星的） dog from outspace.
Can you guess?
海王星
Neptune
水星
Mercury
金星
Venus
地球
Earth
火星
Mars
木星
Jupiter
土星
Saturn
天王星
Uranus
Scientists think Pluto is
too small to be called a planet.
Goodbye!
Life is beginning…
Unit4 Reading
How Life Began on the Earth
Part Two:A guessing game
sharp eyes, remeber quickly



What can you see in the video?
Big Bang
globe
atom
violent surface
water
reptile
alien
eggs
mammals
fish
human beings
dinosaur
cowboy
atmosphere
Main idea
After watching the video clip, what is the main idea of this passage?
A brief introduction on how the ______developed and how _____ began on the earth.
life
earth
Para.1

Para.2

Para.3

Para.4

Para.5
A theory about how the universe （宇宙）was formed
The formation(形成)of the earth
The importance of water for life
The development of plants and animals
The arrival of humans and their effects on the earth
Part1: The development of _________
Part2:The development of________

Part Three:Fast reading
the earth
life
Stage 1: The development of the earth(para1-3)
Task 1:Fill in the form on learning plan paper. (para1-2)
(tips:Read the passage carefully , find some detailed information)
Atoms
a cloud of dust
a solid globe
create
Time What happened to the earth
After the Big Bang ______ began to form and
combine to_______ stars
and other bodies.

Several billion years after the “Big Bang”
The earth was still_______________.
Between 4.5 and 3.8 billion years ago
Dust settled into ___________ .
violent
atmosphere
produce
Water
appear
cooled down
Time What happened to the earth
Next ●The earth began to become___________.
●It exploded to _______ C/N, water vapor, etc, which made up__________.

As the earth _________________ ________ began to ___________on its face.

1.Why was the earth different from other plantes?
2.Why is water so important for the beginning of life?


Task2:
1.Why was the earth different from other plantes?
A . It produced a lot of heat
B . The water remained on the earth
C . A cloud of dust was around the earth
D . It was the oldest planet
2.Why is water so important for the beginning of life?

Because water allowed the earth to dissolve harmful gases into oceans and seas, which made it possible to develop life.
Task3:
Read para(4-5) and put the development of life in time order.
(tips:Find out and underline key phrases which can show a time line, such as ...later,...ago)


Stage2: The development of the life (para4-5)
??Many millions of years later, the first extremely small plants began to appear on the surface of the water. They multiplied and filled the oceans and seas with oxygen, which encouraged the later development of early shellfish and all sorts of fish. Next, green plants began to grow on land. They were followed in time by land animals. Some were insects. Others, called amphibians, were able to live on land as well as in the water. Later when the plants grew into forests, reptiles appeared for the first time. They produced young generally by laying eggs. After that, some huge animals, called dinosaurs, developed. They laid eggs too and existed on the earth for more than 140 million years. However, 65 million years ago the age of the dinosaurs ended. Why they suddenly disappeared still remains a mystery. This disappearance made possible the rise of mammals on the earth. These animals were different from all life forms in the past, because they gave birth to young baby animals and produced milk to feed them.


Finally about 2.6 million years ago some small clever animals, now with hands and feet, appeared and spread all over the earth. Thus they have, in their turn, become the most important animals on the planet. But they are not looking after the earth very well. They are putting too much carbon dioxide into the atmosphere, which prevents heat from escaping from the earth into space. As a result of this, many scientists believe the earth may become too hot to live on. So whether life will continue on the earth for millions of years to come will depend on whether this problem can be solved.



想一想

（ ） Insects and amphibians appeared.
（ ） Dinosaurs appeared.
（ ） Small plants grew on the water.
（ ） Reptiles appeared.
（ ） Green plants began to grow on land.
（ ） Shellfish and other fish appeared.
（ ） Clever animals with hands and feet appeared.
（ ） Mammals appeared.
1
2
3
4
5
6
7
8
Greenhouse effect
Task4:What problem is caused by human beings?(para5)
putting too much carbon
dioxide into the atmosphere
prevents heat from escaping from the earthinto space
too hot to live on
Whether life will continue on the earth depends on human beings.
Only if we care will we help;
only if we help shall all be saved!
Long long ago, there is an ancient
city called Handan.
Handan Congtai
Fuyang River
Part Five: Discussion
Discuss in groups and give a report to the class.
How can we control the air pollution and make our city a better place to live in?
Goodbye!
Many thanks!