1、Unit 4 Global warming教学目标1) Learn some knowledge about the greenhouse effect and global warming.2) Know the contents of the text well by talking about this topic and reading.3) Discuss the problem of global warming and express your own opinions学情分析There are two meanings of the term “greenhouse effec
2、t“.There is a “natural“ greenhouse effect that keeps the Earths climate warm and habitable(suitable for people to live in). Without it, scientists estimate that the average temperature on Earth would be colder by about 30 degrees Celsius (54 degrees Fahrenheit), far too cold to sustain(维持) our curre
3、nt ecosystem. In other words,the normal greenhouse effect is a natural process which is to some degree beneficial to us.重点难点Master the main idea of the first five paragraphs by talking about the topic.教学过程活动 1 【讲授】Unit 4Teaching procedures:Step I. GreetingsGreet the whole class as usual.Step II. Lea
4、d-inLead to the topic by showing an article to the students and let students know about two types of greenhouse effect (“natural“ greenhouse effect and “man-made” greenhouse effect) and their exact meanings.Step III. Analyze two graphs to learn the main idea of the first five paragraphs.From the fir
5、st graph, we can see that during the 20th century the temperature of the earth rose about one degree Fahrenheit.All scientists agree with the view that the increase in the earths temperature is due to the burning of fossil fuels like coal, natural gas and oil to produce energy.More such burning mean
6、s more carbon dioxide added to the atmosphere.We can see clearly that the levels of carbon dioxide have increased greatly over the past decades.Higher levels of carbon dioxide means sharper increase of the temperature. The phenomenon is called global warming.There has been a debate towards global wa
7、rming over the past years. Opinions about it vary from person to person.Step IV. Read the whole passage to review the main idea of the first five paragraphs and know the two different opinions.Dr. FosterCarbon dioxide has caused the global temperature to _. An increase of five degrees would be a _ a
8、nd could be very _.Possible results: _(海平面上升)_(洪灾)_(恶劣的风暴)_(干旱)_(饥荒)_(疾病的传播)_(物种的消失)George Hambley:Any warming will be _ with few bad _. More carbon dioxide is a _ thing, which makes crops _ more and will encourage _.Step V. Discuss the statement: We should take immediate action about global warming
9、. Requirement: Write down your reasons and possible measures on your learning sheetStep VI. Presentation.Ask some students to read their reasons and possible reasons loudly to the whole class.Step VII. Assignment.Make up a complete composition in groups. The passage should include your point of view, your reasons and your measures.