1、1Unit 4 Global Warming教材分析.教学内容分析本单元的中心话题是人类当今面对的环境问题，主要探讨了“全球变暖”和“节约能源”等方面的问题。由于人类过多使用不可再生能源，大气中二氧化碳的含量逐年增加，导致全球气温上升。通过学习本单元，让学生了解能源分为“不可再生能源”和“可再生能源” ，帮助学生树立“节约能源、保护环境”的主人翁意识。语言知识和语言技能主要围绕“全球变暖”和“节约能源”这一主题设计的。“热身”(Warming up) 部分要求学生列举家中、学校或其他地方使用能源的物体，指出这些能源的来源，并尽可能多地列举不同的能源。能源可分为两类：一类是可再利用能源；另一类是
2、一次性能源。把前面列举的能源按能否再利用这一标准进行分类。本部分提供了六幅图片，教师可以从识图开始组织教学。还可以让学生搜集一些其他相关图片。这六幅图分别为：风力（wind power） 、燃煤发电站（a coal power station） 、炼油厂（an oil refinery） 、原子能发电站（a nuclear power plant） 、太阳能接受器（solar panels） 、水坝（a hydro dam） 。“读前”(Pre-reading) 部分首先介绍什么是温室、它有什么作用，然后要求学生讨论大气中温室气体的作用。温室是由玻璃构成的建筑，主要用于花果蔬菜的培植。温室是由
3、玻璃构成的建筑，主要用于花果蔬菜的培植。温室能阻止热量散发，因而能帮助植物度过寒冷的时期。该部分的讨论有利于学生预测课文内容和理解阅读课文中的温室气体效应。“阅读”(Reading) 部分是一篇杂志文章，主要讲述了地球温度上升的现象和原因。20 世纪中，地球的温度上升了华氏 1 度。这看上去是一个很小的数字，但相对于自然界的其他现象来说，这个增长速度是迅猛的。这种现象是自然发生的还是人为的？这个问题引起激烈的争论。许多科学家认为，这种变化是人类燃烧矿物燃料所致。这些物质的燃烧产生以二氧化碳为主的温室气体。正因为自然界有温室气体的存在，地球才不至于很冷。但大量排放二氧化碳会使地球普遍升温。对于地
4、球升温，科学家有不同的看法。有些科学家认为，这个问题很严重。地球升温会导致海水上涨、风暴、干旱、饥荒、物种毁灭和疫病等。也有科学家认为，地球升温有利于改善人类生活，比如，庄稼长得更快、产量更高等。文章最后以开放性的问题结尾要求读者思考：对于全球变暖，人类要不要采取措施？“理解”(Comprehending) 部分设置了三个活动。阅读课文中的杂志文章，练习 1 首先就作者、杂志名称、文中提到的科学家、文中出现的曲线图等内容提问，并要求学生概括文章的主题。然后，练习 2 要求学生细读课文，并判断所给六个句子是否符合课文内容。最后练习 3 要求学生小组讨论：We should do nothing
5、about global warming.在小组讨论的基础上，把全班分成正方和反方，举行一个辩论会。“语言学习”(Learning about language) 的词汇学习部分共两个练习。练习 1 让学生重新阅读课文并找出文中一些具有不同词性或不同含义的生词，分辨它们在文中的含义。练习 2 则要求学生使用前几个部分所学的生词来完成与“全球变暖”话题相关的一些句子。语法学习部分中练习 1 让学生通过对比课文中 it 作强调作用的句子与其他句子的区别，发现并熟悉强调句型及其规律。练习 2 则要求学生针对所给句子的划线部分转换句型，练习使用 it 的强调句型。练习 3 则给予学生更广阔的思维空间，
6、让学生根据自己对“全球变暖”话题的认识运用强调句型进行复述或表达自己的观点。“语言运用”(Using language) 部分的“读和写”(Reading and writing)让学生就 WHAT CAN WE DO ABOUT GLOBAL WARMING?进行讨论。欧阳光给关爱地球组织杂志写电子邮件，请2求帮助。杂志回信指出，群策群力，问题可解。他们提出了几个具体措施：1、减少电器的使用；2、尽量步行或骑自行车；3、回收玻璃、塑料、报纸等物品；4、劝父母购买节能产品；5、植树；6、宣传有关知识。阅读之后，教师可以让学生就文中提出的建议进行讨论，并可以让学生提出更多的建议。这样，学生就有了
7、充分的材料去完成写的任务：设计一个海报，介绍减少空气中二氧化碳含量的方法。听力部分是大学生李斌与陈教授的一段对话，讨论能源的使用问题，并学习表达“赞成”或“不赞成”的交际用语。“小结”(Summing up) 部分要求学生就全球变暖、如何减少二氧化碳、强调句、相关词语等方面进行自我评价，判定学习情况：了解还要进一步改进的地方。“学习建议”(Learning tip) 部分介绍首字母大写的规则，要求学生在阅读中学会辨别人名、地名、书名、题目等。.教学重点和难点1. 教学重点：(1)本单元的生词和短语。(2)it 的用法。(3)了解“全球变暖” 、 “能源的种类”和“节约能源”等方面的知识。帮助学
8、生树立“节约能源、保护环境”的主人翁意识。2. 教学难点(1)学会表达同意和不同意、责备和抱怨等日常交际用语。(2)学习 it 在强调句中的用法。(3)学习如何写一幅表达自己观点、劝说他人节约能源、保护环境的海报。(4)学习有关气候、能源、环保的词汇。、教学计划本单元用五课时：第一课时：Warming Up第二课时：Pre-reading, Reading, Comprehending第三课时：Learning about Language第四课时：Using Language第五课时：Summing up-Learning-Tip、教学步骤：Period 1 Warming UpTeachi
9、ng Goals:1. To arouse Ss interest in learning about global warming.2. To get Ss to know the energy source.Teaching procedures:Step 1. Leading-inPurpose: To activate Ss and arouse them to talk about global warming.T: Hello, everyone. Today we are going to read about global warming. But first lets thi
10、nk about what moves the world around .Yes, it is energy. But what is energy?Energy is a fundamental quantity that every physical system possesses; it allows us to predict how much work the system could be made to do, or how much heat it can produce or absorb .In the past, energy was discussed in ter
11、ms of easily observable effects it has on the properties of objects or changes in state of various systems. Basically, if something changes, some sort of energy was involved in that change. Renewable energy sources like wind power 3dont emit carbon dioxide.Step 2 Warming upPurpose: To lead Ss to the
12、 topic of this unit.1. Pair workGet Ss to ask each other the following questions, and then ask them to present it before the class.(1) What is energy?(2) Where does it come from?(3) What energy sources are renewable?(4) What energy sources are non-renewable?2. Group work(1) Get Ss to talk about sour
13、ces of energy according to the following photos.The above pictures can be used for Ss to talk about, and Ss can also talk as much as they can.By learning Warming Up we all know that energy is so important, but where does it come from?There are different forms of energy: Light energy 光能 Heat energy 热
14、能Sound energy 声能 Chemical energy source 化学能源Nuclear energy 核能 Internal energy 内能Kinetic energy 动能 Potential energy 势能能源类型 定义 实例一次能源 直接来自自然界而未经加工转 换的能源 化石燃料、太阳能、核能、生物 燃料、水能等二次能源 由一次能源直接或间接转化而 来的能源 电能、煤气、汽油、沼气、氢能 等可再生能源 不随其本身的转化或被人类利 用而减少的能源 太阳能、生物能、水能、风能、 地热能等非再生能源 随其本身的转化或被人类利用 而减少的能源 化石燃料、核燃料(2) Co
15、nclusion When energy changes from one form to another, the amount of energy stays the same. Energy cannot be made or destroyed. This fact is called “conservation of energy”. Matter can be made into energy through processes like nuclear fission and nuclear fusion.3. Competition: Take the quiz below a
16、nd see whether Ss can fill in the blanks.Things thatuse energy Sources of energy Renewable/non-renewablelights coal (1) _4oil (2) _natural gas (3) _wind (wind power) (4) _sun (solar energy) (5) _uranium (nuclear energy) (6) _water (hydro-electric power) (7) _plant waste (biomass energy) (8) _hot spr
17、ings or geysers(geothermal energy)(9) _heatingtelevisioncassette playervideo recordercomputerfridgestovewashing machinehairdryerthe sea (tidal energy) (10) _Suggested Answers: (1) non-renewable; (2) non-renewable; (3) non-renewable; (4) renewable; (5) renewable (6) non-renewable; (7) renewable; (8)
18、renewable; (9) renewable; (10) renewable4. HomeworkWrite a short composition about sources of energy.Period 2 Pre-reading, Reading, ComprehendingTeaching 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 Procedu
19、res:Step 1. Warming UpPurpose: To arouse Ss interest in learning about global warming.1. Team workAnswer 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: Wh
20、at is this building made of? S1: Its made of plastic.T: Whats its purpose?S2: Plants can grow in it when its 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-readingPurpose: To get Ss to learn about greenhouse gase
21、s.1. Group workNow look at the word “GREENHOUSE GASES”. What does it mean?5Greenhouse 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 in
22、cluding 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
23、 quoted are for the gas alone ;the lower end ,for the gas counting overlaps).Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrousoxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases.Very powerful green
24、house 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 PFCsare the most heat
25、-absorbent.2. Individual workGet 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 t
26、hey agree with one another?(4) What are the two graphs about?(5) What is the main topic of the article?Step 3. Reading1. SkimmingPurpose: 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 p
27、aragraph.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 earths temperature.(3) The increased extra amount of carbon dioxide
28、 traps more heat energy causing the global temperature to go up.(4) The levels of carbon dioxide have increased greatly over the last 100 to 150 years.(5) There are some different attitudes towards the causes of this increase in carbon dioxide.(6) Over the next 100 years the amount of warming could
29、be as low as 1 to 1.5 degrees Celsius but it could be as much as 5 degrees Celsius.(7) An increase of five degrees would be a catastrophe.(8) Future warming would cause the sea level to rise by several meters.(9) Some predict any warming will be mild with few bad environmental consequences.(10) More
30、 carbon dioxide is a positive thing.(11) No one knows what the effects of global warming will be.62. ScanningPurpose: To get Ss to have some details in the text.Read the article carefully. Are these statements true or false? Write a T for each true sentence and an F for each false sentence.(1) The t
31、emperature last century didnt increase much. ( )(2) Everyone believes that global warming is caused by the activities of humans. ( )(3) Janice Foster believes that burning fossil fuels causes global warming. ( )(4) Natural gas is a greenhouse gas. ( )(5) Carbon dioxide is a byproduct of burning foss
32、il fuels. ( )(6) People accept Charles Keeling s data because he took accurate measurements. ( )(7) Flooding could be one of the effects of future global warming. ( )(8) George Hambley believes scientists are just guessing about the effects of global warming.( )(9) Geroge Hambley is worried about th
33、e effects of carbon dioxide on plant growth. ( )(10) It is clear what the effects of global warming will be. ( )Suggested Answers:(1) F (2) F (3) T (4) F (5) T (6) T (7) T (8) T (9) F (10) F3. ListeningPurpose: To train Ss listening ability.Listen to the tape and follow it in a low voice.4. Group wo
34、rkSs are divided into four groups. Each group is supposed to read through each part and then discuss them. Part 1 (Paragraph 1)(1) compare 比较 常见用法： comparewith 把和比较Compared with him, I am fast. compareto 把比作Life is often compared to voyage.(2) come about 发生How did it come about? 那事是怎么发生的? 常见词组：come
35、across 偶遇；碰到 come round 恢复知觉，come along 进展；进行 come to 涉及；到达；共计come out 公开；问世；出版 come to oneself 恢复知觉come up with 想出(4) phenomenon n 现象It is only a social phenomenon, but not a phenomenon of nature. Part 2 (Paragraph 2, 3, 4)(1) fuel n 燃料Dont leave the engine switched on .It wastes fuel.7 拓展：fuel v 加
36、油；补给燃料The car is being fuelled ready to try to beat the speed record.(2) quantities of 大量Large quantities of money have been spent on the bridge. 拓展： a large quantity of 大量的He ate a large quantity of nice.(3) per prep 每; 每一The fruit costs 30 pence per kilo.How much do you earn per week? Part 3 (Para
37、graph 5,6,7,8,9)(1) data n 资料; 数据We havent got enough data(2) result in 导致The accident resulted in the death of two passengers.It resulted in success. 拓展：result from 由于His illness resulted from eating bad food.(3) catastrophe n 突如其来的大灾难；大灾祸The war was a terrible catastrophe in which many people died
38、.(4) climate n 气候We have a mild climate here. (5) consequence n 结果；后果；影响As a consequence of being in hospital, Shelly decided that she wanted to become a nurse. 常见词组：in consequence 因此，由此in consequence of 由于的缘故(6) state vt 陈述；说明The busmen have stated that the strike will continue until general agreem
39、ent is reached about pay and working conditions.(7) range n he just kept on. 拓展：keep on doing 与 keep doing 的区别：keep on doing 表示动作反复发生；keep doing 表示状态或动作的持续。He kept on standing up in class. 他在课堂上一再地站起来。He kept standing there for half an hour without moving.他一动不动地在那里站了半个小时。Step 4. Post-readingPurpose:
40、 To have a deep understanding of the text.1. Group workNow you are going to discuss the statement: We should do nothing about global warming. Follow these instructions:(1) Get into groups of six. Decide which three in your group are going to agree with the statement (Group A) and which three are goi
41、ng to disagree with the statement (Group B).(2) Group A students discuss why they agree with the statement; Group B students discuss why they disagree.(3) Groups A and B get together. They tell each other the reasons for agreeing or disagreeing with the statement.2. Individual work Ask Ss to answer
42、the following questions. Present their opinions to other classmates.(1) What do you think of global warming?(2) Do you think it serious?3. Discussion(1) Global warming refers to an average increase in the earths temperature, which in turn causes changes in climate.(2) Earths climate has been changin
43、g constantly over its 5-billion-year history.(3) The earth could be getting warmer on its own.(4) Scientists are sure about the greenhouse effect. They know that greenhouse gases make the Earth warmer by trapping energy in the atmosphere.(5) Without the greenhouse effect, the earth would not be warm
44、 enough for humans to live.(6) A warmer earth may lead to changes in rainfall patterns, a rise in sea level, and a wide range of impacts on plants, wildlife, and humans.(7) Scientists dont know exactly what will happen in the future. But they can use special computer programs to find out how the cli
45、mate may change in the years ahead.(8) Global warming may be a big problem, but there are many little things we can do to make a difference.Step 5. Reflective thinkingFirst show the following questions to Ss and then ask Ss to discuss them in groups.1. What do you think cause global warming?2. How d
46、oes global warming affect you and others?3. How does global warming affect the nature?94. When do you send gases into the air, which affect the earth? (Use the air conditioner, ride in a car, and use a fridge)Step 6. Homework1.Use the new words and expressions to make some sentences.2.Try to write a
47、 short composition .The title is “How to slow climate change”, beginning with “Global warming does not have to occur .It is possible for the human race to slow down global warming and maybe even remove all of the effect that people have on the climate.”Period 3 Learning about LanguageTeaching Goals:
48、1.To enable Ss to master some useful words and expressions.2.To discover useful structures.3.To get Ss to have knowledge of the grammar point: the use of it.Teaching Procedures:Step 1. Free talkGet Ss to talk about what causes global warming.Step 2. Word studyPurpose: To consolidate the words and ph
49、rases in the text.1. Individual work Go over the new words and phrases in the previous sections. Then complete each sentence with one of those new words or phrases.(1) Charles Keeling collected on the carbon dioxide content in the atmosphere over a forty-year period .He found that the amount of carbon dioxide _ increasi
