英语Unit4《Globalwarming》教案(3)(新人教版选修6)

英语：Unit4《Global warming》教案（3）（新人教版选修6）

Pre-reading, Reading, Comprehending

Teaching Goals:

1.To read about global warming.

2.To get some idea about the effect of global warming.

3.To develop some basic reading skills.

Teaching Procedures:

Step 1. Warming Up

Purpose: To arouse Ss interest in learning about global warming.

1. Team work

Answer the questions below:

(1) Have you ever seen a greenhouse?

(2) How does a greenhouse work?

(3) What do you think greenhouse gases do?

2. Group work

Look at the picture, and ask Ss some questions.

T: What is this building made of?

S1: It’s made of plastic.

T: What’s its purpose?

S2: Plants can grow in it when it’s cold outside.

T: How does it work?

S3: The glass traps the heat from the sun, making the air warm so that plants grow better.

Step 2. Pre-reading

Purpose: To get Ss to learn about greenhouse gases.

1. Group work

Now look at the word “GREENHOUSE GASES”. What does it mean?

Greenhouse gases (GHG) are gaseous components of the

atmosphere that contribute to the greenhouse effect .The major

natural greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect on Earth (not including clouds): carbon dioxide, which causes between 9-26%; and ozone, which causes between 3-7%(note that it is not really possible to assert that such-and-such a gas causes a certain percentage of the GHE, because the influences of the various gases are not additive .The higher ends of the ranges quoted are for the gas alone ;the lower end ,for the gas counting overlaps).

Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases.

Very powerful greenhouse gases that are not naturally occurring include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6), which are generated in a variety of industrial processes.

Each greenhouse gas differs in its ability to absorb heat in the atmosphere. HFCs and PFCs

are the most heat-absorbent.

2. Individual work

Get Ss to answer these questions individually. Then let them discuss the answers.

(1) Who wrote the magazine article? What is the name of the magazine?

(2) What are the names of the three scientists mentioned in the article?

(3) What do they think about global warming? Do they agree with one another?

(4) What are the two graphs about?

(5) What is the main topic of the article?

Step 3. Reading

1. Skimming

Purpose: To get a brief understanding of the text.

Read through the text, preferably the first and the last sentences of each paragraph and write the key sentence of each paragraph.

Key sentences of each paragraph:

(1) A debate over whether it is human activity that has caused the global warming or whether it is just a natural phenomenon.

(2) Many scientists believe people have caused the increase in the earth’s temperature.