Unit 2 Topic 2 Section C教案.doc

Unit 2 Saving the EarthTopic 2 Section C教案教學(xué)目標(biāo)1. Learn some Learn some new words and phrases: on earth, period, millions of, take away, rise, level, refer to2. Learn some useful sentences:(1) The headroom the sun cant escape (2) When it rains or when the wind blows, the earth is taken away.教學(xué)重、難點(diǎn)Learn to talk about the harm of pollution:(1) Forests have become deserts, so more and more sorts of animals and plants are disappearing.(2) As a result, many rivers and lakes are now dead. (3) Too much harmful radiation from the sun passes through the hole and reaches the earth directly.(4) It causes the level of the oceans to rise and the climate of the earth to change.教學(xué)準(zhǔn)備Tape recorder and some pictures.教學(xué)過程Step 1自學(xué)導(dǎo)綱通過檢查作業(yè)，引導(dǎo)學(xué)生開拓思維，提出保護(hù)環(huán)境和水資源的具體措施，復(fù)習(xí)不定代詞和副詞。為學(xué)習(xí)新詞匯作準(zhǔn)備。T:How do you protect our environment and save water?S1:Everyone should plant more trees.S2:We should do everything we can to save water.S3:Everybody should know the importance of forests.S4:Pass laws against water pollution.S5:Collect and reuse waste water.Step 2合作互動(dòng)1.教師由日常對話，引出本課話題，呈現(xiàn)部分新詞匯。T: Whats the weather like today?Ss: Its T: As we know, Beijing often has sandstorms in spring. What causes the bad weather?Ss: Cutting down too many trees. (展示1a第二幅圖畫。)T: Yes. All over the world, people have cut down millions of trees. And trees become fewer and fewer.T: Cutting down too many trees causes the bad weather. How can trees affect the weather?S1: They can keep water from running away. S2: They can stop S3: T: Yes. Trees can stop the wind and water from taking the earth away.T: Anything else?Ss:(允許學(xué)生用漢語回答。)樹能吸收二氧化碳并釋放氧氣。T: Thats right. Trees can breathe in carbon dioxide and breathe out oxygen.T: Where does CO2 come from?S4: Animals breathing.S5: Burning oil. For example, cars and buses.T: Yes. They have polluted the air. Carbon dioxide in the air has increased a lot. This has formed a “blanket” around the earth.T: The heat from the sun cant escape, so the temperature is rising.T: This is called “the greenhouse effect”.T: Because of the greenhouse effect, what happens to the icebergs(冰川)?Ss: Some parts of them change into water.T: So it causes the level of the oceans to rise.T:(展示1a第4幅圖。)Please look at this picture. Around the earth, theres a special kind of oxygen called “ozone”.T: But now air pollution is destroying it and that has made a very big hole in the ozone layer.T: Too much harmful radiation from the sun passes through the hole and reaches the earth.2.教師出示小黑板上的問題，讓學(xué)生再讀一遍課文后回答。(1) Have we changed our planet in many ways?(2) Have people done well to the earth?(3) Why are more and more sorts of animals and plants disappearing?(4) Are many rivers and lakes dead now?(5) Is ozone important to the earth? Why?(6) Has carbon dioxide in the air increased a lot?Step 3導(dǎo)學(xué)歸納使學(xué)生了解各種污染對地球環(huán)境的影響，培養(yǎng)他們的環(huán)保意識。(1)changein many ways(2)important, destroy, too much, harmful radiation, cause cancer(3)increase a lot, blanket, rise, change(4