高中英语必修三第四单元ppt课件

Discussion
We are making the world better.
.
We are making the world worse.
Because they are putting too much carbon dioxide into the atmosphere.
The earth may become too hot to live on .
.
Fast reading
Read the passage quickly and find the main idea.
A brief introduction on how the universe developed and how life began on the earth.
Careful reading
THE SOLAR SYSTEM
地球 _E_a_r_t_h_ 木星 _J_u_p_i_te_r 火星 _M__a_r_s_ 水星 _M_e_r_c_u_r_y_
海王星 _N__ep__tu_n_e 土星 __S_a_t_u_r_n_ 天王星 _U__ra_n__u_s 金星 __V_e_n_u_s__
on the earth.
Answer the following questions.
1. What is the original earth’s atmosphere made up of? 2. Why did scientists believe water is fundamental to the
Let review the evolution of life on the earth.
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After the “Big Bang”, the earth was full of water.
Original cells appeared in the ocean.
The cells in the water began to separate. Small plants came into being.
Para 3:Thleifiempdoertvaencloe opfmwaetnertfor life.
Para 4:The development of plants and animals on the earth.
Para 5: Thhuemararnivabl eoifnhgusmans and their impact
past?
1. What is the original earth’s atmosphere made up 2. of?
Carbon, nitrogen, water vapour, and other gases.
2. Why did scientist believe water is fundamental to the development of life? Because water allowed the earth to dissolve harmful gases and acids into the oceans and seas to ensure a following chain reaction, which made it possible for life to develop.
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The earth is becoming hotter and hotter!
.
What can we do to take care of the
earth?
solar energy
purify air
plant trees
save water
recycle rubbish
prevent desertification
development of life? 3. How did water come into being on the earth? 4. Which kind of life-being first appeared on the earth,
plants or animals? Why? 5. Why were mammals different from all life forms in the
Very small air-breathing creatures. 4. Do you know what the order for the development of plants and animals is?
Ideas about how life began
.
reading
How Life Began on the Earth
Unit 4
Astronomy: the science of the stars
.
How much do you know about the universe?
What are the names of the eight planets that circle our sun? What is their order from the sun?
Free Talk
1. How old is the universe? Several billion years ago.
2. How old is the earth? Between 4.5 and 3.8 billion years ago.
3. Which were the first creature or plants on earth?
3. How did water come into being on the earth?
The explosion of the earth produced water vapor, which turned into water when the earth cooled down.
4. Which kind of life-being first appeared on the earth, plants or animals? Why? At first, small plants began to appear on the surface of the water, they produce oxygen, which encouraged the later development of early shellfish and all sorts of fish.
Early shellfish and all sorts of fish
.
Some animals (amphibian & insects) came to land.
Reptile appeared.
dinosaurs
mammals
Man had evolved from apes.
5. Why were mammals different from all life forms in the past?
They were different because they produced their young from within their bodies and produce milk to feed them.
Read the passage carefully and analyse its structure.
Para 1:Aewaridtehly, aatcmcepotsepdhthereoeraynabdowutattheer
formation of the universe. Para 2:The formation of the earth.
Whether life will continue on the earth depends on human beings.
.
精讲点拨
• The earth became so violent that it was not clear whether the shape would last or not.
• What many scientists believe is that the continued presence of water allowed the earth to dissolve harmful gases and acids into the oceans .
分析句子：
.
Homework
Put the order of development of life.
• （10）1 Insects and amphibians appeared. • （7）2 Dinosaurs appeared. • （3）3 The earth became a solid ball. • （8）4 Small plants grew on the water. • （4）5 Reptiles appeared. • （9）6 Plants began to grow on dry land. • （6）7 The earth was a cloud of dust. • （1）8 Water appeared on the earth. • （5）9 Shellfish and other fish appeared. • （2）10 The universe began with a “Big Bang”. • （12）11 Clever animals with hands and feet appeared. • （11）12 Mammals appeared.
1. A composition about What we can do to take care of the earth? 2. Read and retell the passage to learn the
important and difficult language points.