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第二册第34课
CAI Demonstration Class
Saving The Earth
October 16,2000
By Zhaoxiang Zhou
I. Teaching focus
1.Realize the damage caused to the world and figure out the reasons.
2.Find ways to stop the earth from being polluted by discussing in groups.
II.Teaching approaches
Elicitation, Mutual Interaction
III.Teaching aid
Interactive multimedia teaching
IV.Teaching process
Step 1 Revision
1. Check note-making
Earth: not enough rain, too many cattle, cutting down trees, strong winds
Air: smoke from factories, power stations, cars, chemical rain, accidents at power stations and factories
Water: waste from factories and cities
Step 2 Presentation
1． Present a series of images depicting the natural beauty of the earth, then the pollution. Highlight the sharp contrast between them. Guide the students to the conclusion: The earth used to be much more beautiful than now; the earth is in danger due to the increasing pollution.
2． Study the map on the textbook, then scan the passages to figure out where on the world atlas the damage has happened. Encourage the students to give out their point of view toward the pollution issue.
Step 3 Audiovisual Learning
The students watch a video on the text, then do the following true or false questions.
1. Many parts of the world with large population and plenty of crops have become deserts. T
2. Land may become poor if farmers do not limit the numbers of their cattle. T
3. Good soil is gradually lost these days as trees are being cut down. T
4. Air pollution and water pollution are the two causes of the problem that many parts of the world have become deserts. F
5. Chemicals in the smoke from power stations can travel hundreds of miles in the wind before falling down to the ground in the rain. F
6. After a bad accident at a nuclear power station, 50% of the trees in
7. The writer to explain how water is polluted uses the examples of the accidents in both
8. Once oceans are polluted, they are not able to clean themselves. F
Step 4 Intensive
Read the passages again for some detailed information
1. To say something about the damage that is caused to the world by pollution, using the information from the text. Try to present possible ways to help solve the problems.
Phenomena
Causes
Suggestions
E
A
R
T
H
The area of desert is growing every year.
Cattle eat grass.
Limit the number of the cattle.
Good soil is gradually lost.
Trees being cut down; strong winds blowing the valuable soil away.
Plant more trees and try to protect them.
A
I
R
Air is being polluted.
Factories, power stations and cars produce a lot of waste.
A lot of things have to be done to reduce pollution. New laws should be passed and people should realize how serious the problem is.
A lot of people died from polluted air in both
There were serious accidents that polluted the air.
Trees in the forest are destroyed and fish in the lakes are killed.
Chemical rain.
W
A
T
E
R
In some places it’s no longer safe for swimming, nor is it safe to eat the fish.
Factories and cities produce a lot of waste.
Same as above.
Waste produced from a chemical factory.
2.to summarize the text by giving the main idea of each passage.
Earth:
The area of desert is growing and good soil is gradually lost.
Air:
Chemicals in the smoke cause a lot of damage and serious accidents took place
from time to time.
Water:
Water pollution is caused by man’s waste. The waters of this great lake have been dirtied and 4800 square km of ocean were polluted by oil.
Step 5 Discussion
Appoint one student to host the discussion. The rest of the class fall into groups of 4, changing ideas on the following question.
(1)What kind of pollution can you think of?
(2)Why trees are important?
(3)What are the causes of water pollution?
(4) What can be done to stop land from becoming into desert?
(5) What else do we know about the problems that the earth is facing?
(6) What steps should we take to save the earth?
Step 6 Role play
The students take turns to play the role of a newspaper reporter, making interviews with heads of factories (e.g. A papermaking factory) which are seriously polluting air and/or water. Record the interviews and compose a report.
Step 7 Assignment
（1）Read the additional materials about pollution and do the reading comprehension exercises.
（2）Finish the report.
Thanks for attending this class!
_____________________________________________________________________________--__
资料 我国环境污染现状令人担忧
据专家估计，中国每年因环境污染造成的损失达到二千八百三十亿元人民币，其中，仅水污染一项，估计一年造成经济损失约五百亿元。
据香港《东方日报》报导，自六十年代至今，中国有环境监测的四百三十二条大小河流中，八成受到不同程度的水体污染，其中大江河经过城镇河段的占二成，支流受污染的占六成，全中国二千八百多个湖泊，凡能接纳城镇污水的，大多出现水体负氧化现象。由于地下水过度开采，京津沪大面积出现土地沉降一点五公尺至二公尺，桂林溶岩区三
大气污染造成的经济损失约为二百亿元，由于城市燃煤、工厂排放废气及汽车死气污染，大气中二氧化硫、一氧化碳等有毒悬浮微粒弥漫在城市上空，空气污染导致许多城市肺癌死亡率增至万分之二，全国酸雨覆盖面积已达百分之三十，所有这些损失加起来也等于二百亿元。
而生态环境破坏和自然灾害造成的损失估计高达二千亿元，森林覆盖率由四九年的三成左右，现已下降至不足一成四，草原的严重退化，水土流失面积达一百五十五万平方公里，占国土面积的百分之十六。
同时，城镇建设却仍以每年侵占一百五十万公顷土地的速度发展，破坏自然生态平衡，加上自然灾害带来的损失，每年至少损失二百亿元。
其他污染如固体废物排放、噪音污染等造成的损失也高达一百三十亿元。
专家分析表示，造成环境污染引起的经济损失原因众多，但国家工业规划布局失误，调控措施不力和公民环保意识不强是主要原因。
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