临川二中

精品课件

How Life Began on the Earth

临川二中 2016-01-06 点击次数: 3633

必修3 Unit 4 Astronomy: the Science of Stars

The First Period Reading

How Life Began on the Earth

Teaching Aims:

1. Get students to learn and master some useful words and expressions in the reading passage.

2. Get students to learn about the development of the earth and life.

3. Improve students’ reading comprehension ability.

4. Stimulate students’ interest in science and develop their love of astronomy.

5. Get students to have a deep understanding of the importance of protecting the environment on the earth.

Teaching Important Points:

1. Enable students to learn and master the important words and expressions.

2. Enable students to learn about how the earth came into being and how life began and developed on the earth.

3. Enable students to get some reading skills, such as skimming, scanning and getting the main idea.

Teaching Difficult Points:

1. How to improve students’ reading ability.

2. How to stimulate students to learn about the development of the earth and life.

Teaching Aids:

A tape recorder, computer and screen, some pictures about the beautiful universe, some envelopes contained exercise paper.

Teaching Methods:

Task-based method, Cooperation and Competition, Group Discussion

Teaching Procedures:

Step Pre-reading (5’)

(Before the class, Teacher let students enjoy some beautiful pictures about our beautiful universe.)

Task 1 Leading in(Individual work)

(Teacher greets the whole class as usual.Then ask the following questions and ask students to answer them as quickly as possible.)

T: As we know, our universe is so large and full of mysteries. But have you thought about such questions: How the earth began?

How life began on the earth?

T: Well, in ancient times, there are many beautiful stories or legends about the answers. Do you know the stories? Can you tell us the stories? Who would like to share the stories with us? Any volunteer?

(At least 4 students come up to the platform to tell the stories. At the same time, teacher show some pictures about the stories on the screen, which are 盘古开天地――Pan’gu separated the sky from the earth; 女娲造人――The Goddess Nuwa created human beings from the clay; 上帝七天造人――God created the world and the first man, Adam and the first woman, Eva. 普罗米休斯造人并盗取天火――The God Prometheus created the mankind and stole fire from the heaven.)

T: Thank you for your good job. Well, all these stories are beautiful mythologies(神话) created by our ancestors. They are in different culture, two are Chinese culture and the other two are western culture. But do you think they are true or not? Do you believe them?

Ss: No.

T: Why? Right. Because they are superstitious(迷信的) and have no scientific evidence(没有科学根据). But what are the scientific ideas of How the earth began and How life began? Today, we are going to read a short passage about the questions. Now please turn to page 25.

(师板题How Life began on the Earth)

Task 2 Predicting (Individual work)

(Teacher ask students to predict the general idea of the passage according to the title and the pictures.)

T: At first, please catch sight of(暼一眼) the picture on page 25 and the picture on page 26. After a glance of the title and the pictures in the passage, what do you think the passage is about?

(Students give their own answers.)

T: Maybe the passage will tell us How the earth began and How life on the earth began. (让生抓住标题中的关键词――How Began earth, life. )

五个问题:How did the universe begin?

How did the earth begin?

How important is water to the development of life?

How did life begin?

How will life continue to live on the earth?

Step Fast Reading

Task 3 Skimming(略读) Individual work

T: Next, I will give you 2 minutes to read the passage as quickly as they can. Then, try to answer these questions:

1. What is the main idea of the text?

2. How many parts can the text be divided into? What’s the main idea of each part?

T: (师指导学生略读获取文章主旨大意的技巧)As we know, the topic sentence often lies at the beginning of the paragraph or at the end of the paragraph. Sometimes lies in the middle.
Thinking of the students’ level, after the Ss’ discussion, I will show the main idea for each paragraph in a wrong order on the screen, then let the students to match them.

Answers:

Paragraph 1 A: Water is important for life.


Paragraph 2 B: The universe began with a “Big Bang”, after which stars and other bodies(天体) came into being.

Paragraph 3 C: How the earth came into being.

Paragraph 4 D: The birth of humans, who have brought problems to the earth.

Paragraph 5 E: The development of plants and animals on the earth.

The text is mainly about How Life on the Earth Began. (文章的标题即主旨)

T: So what you predicted is right. Ok, let’s read the text carefully.

Purpose: This step is to direct students to use skills and strategies to get the general idea of the passage in the shortest time and cultivate students’ good reading habit and fast reading ability.

Step Careful Reading Paragraph by Paragraph

Paragraph 1

T: From the first paragraph, we know, according to a widely accepted theory, the universe began with a “Big Bang”. That’s to say, the Big Bang is just a theory. Right? How much do you know about the Big Bang? Who would like to tell us something about the “Big Bang”? ×××, please?

S: 宇宙大爆炸是一种学说、理论设想。大约在140亿年前,宇宙中所有的物质都高密度地聚集在一个点上,有着极高的温度和密度,因而发生了巨大的爆炸。“大爆炸”使得宇宙中的物质四分五裂,并不断地向外膨胀扩张,形成中子、质子、电子、光子和中微子等基本粒子形态。随着温度的下降,逐步凝聚成星云,星云进一步形成各种各样的恒星和星系,于是便形成了我们现在所看到的宇宙。
T: Wonderful. So you must be very interested in Astronomy. Now, let’s watch a short video. I hope it can help you understand the “Big Bang” well.

(Teacher play the short video------探索与发现 宇宙大爆炸)
Paragraph 2

TNow let’s come to Paragraph 2. Read it carefully and finish this task.

Task 4 How did the earth came into being? Fill in the chart on the screen.

Time

The earth

Several billion years after the “Big Bang”

A cloud of dust

Between 4.5 and 3.8 billion years ago

A solid globe

Exploded with fire and rock

Produce C/N water vapor, etc.

As the earth cooled down

Water began to appear

Paragraph 3

TNow let’s read Paragraph 3 quickly. Try to answer these questions.

Q1: Why was the earth different from the other planets?

Because water remained on the earth , but other planets have no water.

Q2: Why is water so important for the beginning of life on the earth?

Because water allowed the earth to dissolve harmful gases into oceans and seas.

Paragraph 4-5

TNow let’s come to Paragraph4-5, the development of life on the earth. Read them carefully and finish a task.

Task 5 Competition between groups

T: Now, I’ll divide all of you into 9 small groups. Each group has 8 students. You eight, one group. Next you eight, one group. …. Each group should have a reporter. The reporter should take notes about others’ words or the results. And he must stand for his group to report the result before the class.

T: Let’s have a competition. I’ll give each group an envelop. Now open the envelop and take out small pieces of paper. Try to put them into right order, according to the time order mentioned in the text. Let’s see which group get the right answer first. Understand? Now, begin. Hurry up!

If you get the answer first, come here and write your answer to the blackboard.

(生分小组争分夺秒把信封里的小纸条排序, 并把答案写在黑板上。)

T: Ok. Next let’s watch a short movie. Then check the answers on the blackboard.

(Teacher play the short video------“生物进化电影”)
Then teacher show the right answer on the screen, and check the answers.

K. The universe began with a “Big Bang”

D. The earth was a cloud of dust

B. The earth became a solid ball

J. Water appeared on the earth

H. Small plants grew on the water

E. Shellfish and other fish appeared

I. Plants began to grow on dry land

A. Insects and amphibians appeared

C. Reptiles appeared

G. Dinosaurs appeared

L. Mammals appeared

F. Clever animals with hands and feet appeared

T: Finally, clever animals with hands and feet appeared. Can you guess what kind of animals are they?

Ss: We human beings.

T: Right. But are human beings looking after the earth well? What problems are they causing?

putting too much carbon dioxide into the atmosphere global warming (green house effect) the earth may become too hot

T: Right, it's too bad\serious. Then can you imagine what our future will be like as a result of the global warming? Try to fill in the blanks.

Ice in the North Pole melts

Sea level rises

Plants & animals will die out

There will be no life on the earth

Step Summary & Discussion

T: That’s all for this passage. Next, let’s complete a summary about this text. I will give you 3 minutes to find the words. You can cooperate with your partners.

Task 6 Summary of the text

After the “Big Bang”, the earth was a cloud of ______, which later _______ into a solid globe. It _________ with fire and rock, which produced carbon, nitrogen, water_______, and other gases. Then water appeared on the surface of earth. Many millions of years later, small plants grew on water. They multiplied and_____the seas with oxygen,which encouraged the development of early shellfish and all kinds of ______.Next green plants grew on_____.When the plants grew into ________, reptiles appeared for the first time. They produced young generally by_______ eggs. After dinosaurs disappeared, __________ appeared on the earth. At last humans appeared and ______ all over the world. But they are putting too much carbon dioxide into the ____________. So whether life will continue on the earth will ________ on whether this problem can be solved.

Answers: dust, settled, exploded, vapour, filled, fish, land, forests, laying eggs, mammals, spread, atmosphere, depend.

T: Next, let’s have a group discussion.

Task 7 Discussion

? (1) As a student, what little things can we do to solve(解决) the problem of global warming and to protect the earth ?

(Teacher give students 3 minutes to discuss about the question. Then Teacher choose a few reporters to report their results and communicate with other students.)

Teacher can give some clues: live a low-carbon life ; ride bicycles ; plant trees ; save water ; recycle rubbish ; environmental friendly bags ; solar energy

(2) A United Nations Climate Change Conference (联合国气候大会) will be held next month. Our class is going to write a letter to the conference. What would you like to say in the letter? Do you have any good ideas about how to protect our earth?

Step Conclusion & Homework

T: Ok, today we ’ve learned a short passage about the scientific ideas of How Life Began on the Earth. We also know the importance of protecting our earth. I wish all of you must take action to protect our earth. So we can continue living on the earth for millions of years to come.

Homework:

1. Write a letter.

2. Read the passage again and try to retell it in your own words.

返回