概要写作 说明文 学案1.doc

Writing TaskTeaching Focuso Summarize the main idea through the title, topic sentences and key words.o Identify the important points to support the main ideao Use proper transitions to weave sentences or paragraphsWrite a summary of exposition in no more than 60 words.PrewritingPollution in Its Many FormsOne of the most serious problems facing the world today is pollution. That is the pollution of air, land and water by all kinds of chemicals such as poisonous gases, waste materials and insecticides. Pollution has upset the balance of nature, destroyed many forms of wildlife and caused a variety of illnesses. It occurs in every country on Earth but is most serious in industrial countries. Breathing polluted air is very common to most people, especially those living in cities. In heavily industrialized areas, fumes from car exhausts and thick smoke from factory chimneys can be seen darkening the atmosphere. This would reduce visibility and make the air unpleasant to breathe. Large scale burning of fossil fuels, such as coal, gas and oil, in homes and industries also produces a wide range of pollutants. This includes sulfur dioxide which damages plants, destroys buildings and affects health. Other known pollutants are carbon monoxide, nitrogen dioxide and dirt particles. The fumes produced by car exhausts and factories would normally spread in the air, but sometimes they are trapped by air layers of different temperatures. The result is a fog-like haze known as smog. Domestic rubbish is another very serious pollution problem. The average American citizen throws away nearly one ton of rubbish every year. Much of this consists of plastic, metal and glass packaging that cannot be broken down naturally. Instead, it lies with old refrigerators, broken washing machines and abandoned cars in huge piles for years without decaying. Each year the problem of rubbish disposal becomes more serious.Like rivers, oceans have been used as dumping grounds for waste of all kinds. One of the recent sources of sea pollution is oil and millions of tons of it spill into the sea each year. Oil not only pollutes beaches, it also kills fish and seabirds. Step 1: Read the following passage and complete the table.PartFunctionI. Para. _II. Paras. _ to _Title: _Topic sentence: _What is the passage mainly about? _ Step 2: Read the title and the first paragraph. Find out the topic sentence in the first paragraph and what the passage is mainly about. Step 3: Make a list of the three supporting points in the passage.1) _2) _3) _Drafting and Revising Step 4: Summarize each supporting point with one or more of the authors examples or illustrations.Breathing polluted air is very common to most people, especially those living in cities. In heavily industrialized areas, fumes from car exhausts and thick smoke from factory chimneys can be seen darkening the atmosphere. This would reduce visibility and make the air unpleasant to breathe. Large scale burning of fossil fuels, such as coal, gas and oil, in homes and industries also produces a wide range of pollutants. This includes sulfur dioxide which damages plants, destroys buildings and affects health. Other known pollutants are carbon monoxide, nitrogen dioxide and dirt particles. The fumes produced by car exhausts and factories would normally spread in the air, but sometimes they are trapped by air layers of different temperatures. The result is a fog-like haze known as smog. 1. Read the first sentence of the second paragraph and underline the key words which tell us about the causes and effects. 2. Summarize the supporting points of each paragraph in one well-organized sentence.Para. 2: _Para. 3: _Para. 4: _The first Draft:_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 60_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Step 5: Complete the first draft.Checklisto Does his/her summary begin with a sentence that states the main idea?o Do he/she use his/her own words?o Do he/she avoid adding his/her own comments?o Do he/she use restatement to emphasize the main idea and unify his/her writing?o Are there any mistakes in spelling, grammar and punctuation? If so, please underline and correct them. Step 6: Pair work - Read your partners draft and finish the checklist. Step 7: Revise the first draft and write an improved summary.The improved summary:_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _