高中英语必修三第四单元ppt课件

1、.,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?,地球 _ 木星 _ 火星 _ 水星 _,海王星 _ 土星 _ 天王星 _ 金星 _,Earth,Jupiter,Mars,Mercury,Neptune,Saturn,Uranus,Venus,1. How old is the univ

2、erse? 2. How old is the earth? 3. Which were the first creature or plants on earth? 4. Do you know what the order for the development of plants and animals is?,Several billion years ago.,Between 4.5 and 3.8 billion years ago.,Very small air-breathing creatures.,Free Talk,.,Ideas about how life began

3、,.,reading,How Life Began on the Earth,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,Para 1:,Para 2: Para 3: Para 4:,Para 5:,A widely accepted theory about the formation of the univers

4、e.,The formation of the earth.,The importance of water for life.,The development of plants and animals on the earth.,The arrival of humans and their impact on the earth.,Read the passage carefully and analyse its structure.,earth, atmosphere and water,life development,human beings,1. What is the ori

5、ginal earths atmosphere made up of? 2. Why did scientists believe water is fundamental to the 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

6、past?,Answer the following questions.,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, whic

7、h made it possible for life to develop.,What is the original earths atmosphere made up of?,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, plan

8、ts 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.,5. Why were mammals different from all life forms in the past?,They were different because they produced their

9、 young from within their bodies and produce milk to feed them.,（ ）1 Insects and amphibians appeared. （ ）2 Dinosaurs appeared. （ ）3 The earth became a solid ball. （ ）4 Small plants grew on the water. （ ）5 Reptiles appeared. （ ）6 Plants began to grow on dry land. （ ）7 The earth was a cloud of dust. （

10、）8 Water appeared on the earth. （ 9 Shellfish and other fish appeared. （ ）10 The universe began with a “Big Bang”. （ ）11 Clever animals with hands and feet appeared. （ ）12 Mammals appeared.,8,7,5）,6,4,1,10,3,9,2,Put the order of development of life.,12,11,Let review the evolution of life on the eart

11、h.,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.,.,Early shellfish and all sorts of fish,Some animals (amphibian & insects) came to land.,Reptile appeared.,dinosaurs,mammals,Man had evo

12、lved from apes.,.,We are making the world better.,We are making the world worse.,Discussion,.,Because they are putting too much carbon dioxide into the atmosphere.,The earth may become too hot to live on .,.,The earth is becoming hotter and hotter!,solar energy,plant trees,recycle rubbish,prevent de

13、sertification,save water,purify air,What can we do to take care 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