1. the science of the stars
Unit 4
Astronomy:
the science of the stars

2. 冥王星 土星
海王星 木星
天王星 金星 地球
The Solar system 水星 火星

3. How life began on the earth?
Big Bang
Big Bang

4. Task 1: Skimming
1. Read the text quickly and match each paragraph with its main idea.
Paragraph A. The formation of the earth.
Paragraph B. The importance of water for life.
Paragraph C. The arrival of human beings and
their effect on the earth.
Paragraph D. A widely accepted theory about
the formation of the universe.
Paragraph E. The development of plants and
animals on the earth.

5. 2. According to the exercise above, try to write down the main idea of the text.
The text mainly tells us____________
_________________________________.
how the earth
formed and how life began on the earth

6. Task 2: Scanning A B Scan the text and then choose the best answer
1. What began to appear on the earth’ s surface when it cooled down?_____
A. Water B. Gases C. Acids D. Carbon
2. How did the atmosphere on the earth appear?____
A. It came from space B. It came from the explosion
C. It came from the oceans D. It came from the forests A B

7. A C D 3. Why did plants appear earlier than animals?_______
A. Because plants could produce oxygen, which was important
for animals;
B. Because plants were more advantage than animals;
C. Because animals needed more water;
D. Because plants needed more water;
4. From the last paragraph we can infer that the author is _________about the future of life on the earth.
Confident B. sad C. concerned D. angry
5. According to the text we can know________.
Only the earth has life on it in space;
Oxygen in the atmosphere on the earth came from the Big Bang;
Humans are the cleverest animals of the earth;
Plants played an important part in the appearance of animals; C D

8. Task 3: Careful reading How life began on earth
Fill in the blanks with key words according to what you have read from each paragraph.
How life began on earth
The universe began with a “_________” .
Atoms formed and combined to create __________________.
Big Bang
stars and other bodies ↓

9. For several billion years after the big bang, the earth was still a______________. Between 4.5 and 3.8 billion years ago, the dust settled into a _________ . The earth _________to produce carbon, nitrogen, water vapour and other gases; The gases made the earth’s __________ ; As the earth cooled down, _______appeared on the earth ; ↓ The continued presence of water ________harmful gases and acids; Life began to develop ↓
cloud of dust
solid globe
exploded
atmosphere
water
dissolved

10. a chain reaction ↓ plants animals human beings
The first ________________in water filled water with________
The early_________________
developed
Next _________________grew
on land
Land animals(_____,________)
Followed.
Later the plants grew into_____
______, dinosaurs and_______
appeared.
small plants
shellfish and fish
oxygen
green plants
insects
amphibians
forests
Reptiles
mammals ↓
human beings
About 2.6 million years ago, ______________________________ appeared and spread all over the earth
a chain reaction

11. 2. Think about the following questions and discuss in group.
①The text is developed in the order of _____. The italicized(斜体字) words above help the author describe the complex process of the evolution of life on the earth clear. Can you find more in the text?
plants
animals
The first small plants in water filled water with oxygen
The early shellfish and fish
Developed.
Next green plants grew
on land
Land animals (insect, amphibians)
Followed.
Later the plants grew into forests
Reptiles, dinosaurs and mammals
Appeared.
time
For several billion years after the “Big Bang”, between 4.5 and 3.8 billion years ago, many millions of years later, for more than 140 million years,65 million years ago, about 2.6 million years ago, now. but, first, next, later, after that, thus, but, so.

12. ② What problem did human beings cause on earth?
③What should we do to make life continue to survive on the earth?
They are not looking after the earth very well.
protect the environment, plant more trees, put less carbon dioxide into the atmosphere, …

13. Task 4: Homework Discuss in groups and give a report to the class.
How life began on earth is one of the biggest puzzles that scientists found hard to solve. What other puzzles are hidden in the passage? Find them out and do some research.

14. Thank you!