高一英語(yǔ)（下）必修四Unit 2課時(shí)教案Period 4

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1、 Period 4 Using language-----Organic farming GOALS: 1. To learn what is organic food. 2. To express freely with the language the students have learned. 3. The students will become more aware of the quality of the food they are eating & buy more green food.. TEACHING PROCEDURES: Step 1 First r

2、eading Read the passage, then find out the topic sentence of each paragraph Para 1: What is organic farming? Para 2: The fertilizer that organic farmers prefer is natural waste from animals. Para 3: Organic farmers insist on changing crops every two or three years. Step 2 Second reading Read

3、the text again and answer the following questions: 1. What is organic farming? 2. What problems are caused by using chemical fertilizers? 3. Why do organic farmers grow peas or soybeans after corn or wheat? Possible answers: Organic farming means growing crops without chemical fertilizers.----g

4、reen food There are three problems. Firstly, chemical fertilizers affect the soil and the water supply badly. Secondly, they allow farmers to grow the same crop year after year and exhaust the soil. Thirdly, they kill both helpful and harmful pests. Farmers grow peas or soybeans after corn

5、or wheat so that peas and beans can put minerals back into the soil, making it rich and healthy and ready to grow more wheat or corn. Step 3 Third reading Read the text again, and fill in the following forms. Advantages of organic farming Reasons 1.Farmers use natural waste from animals. 1.

6、This makes the soil richer in minerals and so more fertile. 2.The soil is not exhausted. 2.Peas and soybeans renew the minerals in the soil becomes rich and healthy. 3.They use the soil to best advantage. 3.They plant crops that need surface soil and next crops that grow at a deeper level. So th

7、e wind and water doesn’t carry away the soil. All the richness of the soil is used. What are the disadvantages of using chemical fertilizers? 1. Leaving chemicals in the ground for a long time is not good for the soil or the water supply. 2. Farmer often grow the same crop year after year. As a r

8、esult, the soil gets exhausted. 3. Chemical fertilizers kill both helpful and harmful bacteria and pests. Step 4 Retelling Retell the text according to the chart: Organic farming I. Organic farming…natural / chemical fertilizers II. Farmers prefer natural waste from animals. Natural fertilize

9、r 1. make…richer and more fertile 2. reduce…and help…grow… 3. air, soil, water, food supply…free from chemicals Chemical fertilizer 1. leaving…is not good 2. grow…year after year 3. kill … bacteria & pests III. Farmers change crops every two or three years. …to make sure what is left … Ste

10、p 5 Discussion What is “Genetically Modified Food”? GM Food is most commonly used to refer to crop plants created for human or animal consumption using the latest molecular(分子的) biology techniques. These plants have been modified in the laboratory to enhance desired traits(特點(diǎn)) such as increased re

11、sistance to herbicides(除草劑) or improved nutritional content. Through GM it is possible to change fruits, vegetables & even animals. We can change the way they grow, where they can grow, how they will taste, what color & what shape they will have. For example: watermelon onion wheel Discussi

12、on：Do you think it is good or not to eat GM Food? Benefits Crops ? Enhanced taste and quality ? Reduced maturation(成熟) time ? Increased nutrients, and stress tolerance(抗藥力) ? Improved resistance(抵抗) to disease, pests, and herbicides ? New products and growing techniques Animals ? In

13、creased resistance, productivity, hardiness, and feed efficiency ? Better yields of meat, eggs, and milk ? Improved animal health and diagnostic methods Environment ? "Friendly" bioherbicides and bioinsecticides ? Conservation(維護(hù)) of soil, water, and energy ? Better natural waste managem

14、ent ? More efficient processing Society ? Increased food security for growing populations Controversies Environmental hazards ? Unintended harm to other organisms ? Reduced effectiveness of pesticides (殺蟲劑) ? Gene transfer to non-target species Human health risks ? allergens(過(guò)敏)

15、? Unknown effects on human health Economic concerns ? Bringing a GM food to market is a lengthy and costly process Step6 Assignment Find some useful information on the Internet by searching : http://www.spcpweb.org/yards/?gclid=CJGP4daptYoCFRhCTAodfXhyOg http://www.rain.org/~sals/my.html 單位：湖北省荊門　姓名：李國(guó)　E_mail：liguo619@