北师大版高二选修8教案： Unit 22 Period 2.doc

the second period lesson 1 global warming (i)teaching goals 教学目标1. target language目标语言a. 重点词汇和短语consensus, beyond, relevant, refer, bounce, pin, coincidence, condemn, federal, reservation, sacrifice, advocate, recycle, substitute, beyond ones control, take action, ahead ofb. 重点句子in the last few decades, scientists have reached consensus and reported that human beings are causing changes in the earths climate something previously seen as beyond our control.2. ability goals 能力目标 learn what global warming is and enable students to learn its causes and consequences.3. learning ability goals学能目标by reading an article help students to learn how they can help solve the problem of global warming.teaching important points教学重点what human activities are causing global warming and how we can help solve the problem of global warming.teaching difficult points教学难点how we can help solve the problem of global warming.teaching methods教学方法 listening, reading, discussing.teaching aid 教具准备multimedia computer.teaching procedures & ways 过程与方式step i leading inin this procedure students will talk about the causes and consequences of global warming. begin the lesson by asking students to discuss the questions in before you startt: good morning /afternoon, class!ss: good morning/ afternoon, mr. /msshow the pictures on page 6 on the powerpoint and ask students to discuss them in groups.t: please look at the pictures and discuss in groups what you can see in the pictures.t: yesterday we learned from the passage in culture corner that gases from burning coal and oil are the major causes of global warming. did you make your survey on how students come to school?s1: i asked 40 students. ten in the forty come to school by bus. twenty-one ride bicycles. eight of the forty take a car and only one walks to school. .t: from the survey you made we can see most of students in our school take a green way to school. im glad we are not having so many cars. because gases pumped into the atmosphere from cars will speed up global warming. have you noticed that in 2006 we had a very warm winter? experts say global warming has changed the climate in china. in this class we are going to learn more about global warming. we will read an article “can we take the heat?” before we start the text, please discuss the question in before you start. step ii before you startdiscuss the two questions in before you start and work out the meanings of the given words.t: ok, open your books and discuss the question in before you start on page 6. which countries do you think contribute more to global warming, developed countries or developing countries?ss: developed countries. because they have more cars and factories and gases from cars and factories are the major cause of global warming.t: good answer. please scan the text for the given words in ex2 and try to work out their meaning.while students are discussing the words, teacher should walk around the classroom and give necessary help when needed.several minutes later, ask students to present their answers either in english or chinese. students may even be encouraged to explain the meanings using pictures. show the suggested answers on the powerpoint.step iii read to learndeal with the reading part.scanningask students to scan the text and find what exactly global warming is.t: what is the title of lesson 1?ss: global warming.t: do you know what exactly global warming is? please scan the text and find the answer in the text.ss: global warming refers to an average increase in the earths temperature.t: quite good! then skim the text and find what human activities are causing global warming.s: as a result of increased industry, agriculture, the cutting down of forests, the increase in transport and the burning of fuels, nearly 6 tones of carbon dioxide goes into the atmosphere every year for every one of the earths 6 billion people. over the last 100 years, the global average temperature has increased by 1f. if we continue to produce carbon dioxide and other gases in such quantities, we are condemning life on earth and should expect severe consequences.skimming show the following form on the powerpoint and ask them to work in groups and complete the form.termdefinitioncauses consequenceshow to solve the problemglobal warmingfive minutes later, show the suggested answers on the powerpoint.termdefinitioncauses consequenceshow to solve the problemglobal warmingrefers to an average increase in the earths temperature.when greenhouse gases in the atmosphere increase, more heat is trapped.(the greenhouse effect)the earths temperature rises.governments action and each person should play their part (small changes made by everyone worldwide).ask students to skim the text and then finish ex3 on page 7. students may discuss the questions in groups.t: look through the questions in ex 3 on page 7 first. then skim the text to find the answers. then check the answers with the whole class.suggested answers:1. global warming is an average increase in the earths temperature.2. increased industry, agriculture, the cutting down of forests, the increase in transport and the burning of fuels are causing global warming.3. by 1f.4. yes, they are. because greenhouse gases trap heat from the sun in the earths atmosphere. otherwise the earth would be very cold and unsuitable for life.5. we can take public transport, recycling, using low-flow shower heads, buying efficient light bulbs to stop global warming.step iv explanationduring this procedure teacher will play the tape for students. students will underline the difficult sentences. after listening to the tape, teacher will explain the text and deal with language problems. t: after doing the comprehension of the text, lets deal with some difficult language focuses. now i will play the tape for you .please make a mark where you have difficulties.after listening to the tape, explain the difficult sentences to students. before explaining the difficult points, students are asked to refer to the notes to the text on page 114. t: do you have any difficulties with the text？s1: could you please explain the second paragraph to us?t: the second paragraph tells us the association greenhouse gases have with global warming. the “greenhouse effect” often gets a bad rap because of its association with global warming, but the truth is we couldnt live without it. life on earth depends on energy from the sun. about 30 percent of the sunlight that beams toward earth is deflected by the outer atmosphere and scattered back into space. the rest reaches the planets surface and is reflected upward again as a type of slow-moving energy called infrared radiation. as infrared radiation is carried aloft by air currents, it is absorbed by “greenhouse gases” such as water vapor, carbon dioxide, ozone and methane, which slows its escape from the atmosphere. although greenhouse gases make up only about 1 percent of the earths atmosphere, they regulate our climate by trapping heat and holding it in a kind of warm-air blanket that surrounds the planet. this phenomenon is what scientists call the greenhouse effect. without it, scientists estimate that the average temperature on earth would be colder by approximately 30 degrees celsius (54 degrees fahrenheit), far too cold to sustain our current ecosystem. while the greenhouse effect is an essential environmental prerequisite for life on earth, there really can be too much of a good thing. the problems begin when human activities distort and accelerate the natural process by creating more greenhouse gases in the atmosphere than are necessary to warm the planet to an ideal temperature. today, the increase in the earths temperature is increasing with unprecedented speed. to understand just how quickly global warming is accelerating, consider this: during the entire 20th century, the average global temperature increased by about 0.6 degrees celsius (slightly more than 1 degree fahrenheit). using computer climate models, scientists estimate that by the year 2100 the average global temperature will increase by 1.4 degrees to 5.8 degrees celsius (approximately 2.5 degrees to 10.5 degrees fahrenheit). now please read the first sentence in the second paragraph. whats the function of that-clause?s1: it is an attributive clause modifyi