必修4Unit-2-Chemical-or-Organic-Farming公开课优质获奖课件

1、Unit 2 Chemical or Organic Farming?Warming upWarming upWhat do farmers need to grow food?They need+Warming upFertilizers?Warming upChemical fertilizersNatural fertilizers_ farming_ farmingchemicalorganicChemical or Organic Farming?Pre-readingChemical or Organic Farming?Predict what we will know from

2、 the passage. Well know. Chemical or Organic Farming?Read for the structureTask 1 Underline the topic sentence of each paragraph.A What are some of the problems caused by chemical fertilizers? First, they damage the land by killing the helpful bacteria and pests as well as the harmful ones. Chemical

3、s also stay in the ground and underground water for a long time. This affects crops and, therefore, animals and humans, since chemicals get inside the crops and cannot just be washed off. These chemicals in the food supply build up in peoples bodies over time. Many of these chemicals can lead to can

4、cer or other illnesses. In addition, fruit, vegetables and other food grown with chemical fertilizers usually grow too fast to be full of much nutrition. They may look beautiful, but inside there is usually more water than vitamins and minerals. Read for the structureTask 1 Underline the topic sente

5、nce of each paragraph.A. What are some of the problems caused by chemical fertilizers?B. ._C. ._D. ._Read for the structureTask 1 Underline the topic sentence of each paragraph.B With these discoveries, some farmers and many customers are beginning to turn to organic farming. Organic farming is simp

6、ly farming without using any chemicals. They focus on keeping their soil rich and free of disease. A healthy soil reduces disease and helps crops grow strong and healthy. Organic farmers, therefore, often prefer using natural waste from animals as fertilizer. They feel that this makes the soil in th

7、eir fields richer in minerals and so more fertile. This also keeps the air, soil, water and crops free from chemicals. Read for the structureTask 1 Underline the topic sentence of each paragraph.C Organic farming also use many other methods to keep the soil fertile. They often change the kind of cro

8、p in each field every few years, for example, growing corn or wheat and then the next year peas or soybeans. Crops such as peas or soybeans put important minerals back into the soil, making it ready for crops such as wheat or corn that need rich and fertile soil. Organic farmers also plant crops to

9、use different levels of soil, for example, planting peanuts that use the grounds surface followed by vegetables that put down deep roots. Some organic farmers prefer planting grass between crops to prevent wind or water from carrying away the soil, and then leaving it in the ground to become a natur

10、al fertilizer for the next years crop. These many different organic farming methods have the same goal: to grow good food and avoid damaging the environment or peoples health. Read for the structureTask 1 Underline the topic sentence of each paragraph.D Over the past half century, using chemical fer

11、tilizers has become very common in farming. Many farmers welcomed them as a great way to stop crop disease and increase production. Recently, however, scientists have been finding that long-term use of these fertilizers can cause damage to the land and, even more dangerous, to peoples health. Read f

12、or the structureThe topic sentences of each paragraph:A. What are some of the problems caused by chemical fertilizers?B. With these discoveries, some farmers and many customers are beginning to turn to organic farming.C. Organic farmers also use many other methods to keep the soil fertile.D. Recentl

13、y, however, scientists have been finding that long-term use of these fertilizers can cause damage to the land and even more dangerous, to peoples health.Task 2 Put the four paragraphs in order. ABCD_ _ _ _ Read for the structureThe topic sentences of each paragraph:A. What are some of the problems c

14、aused by chemical fertilizers?B. With these discoveries, some farmers and many customers are beginning to turn to organic farming.C. Organic farmers also use many other methods to keep the soil fertile.D. Recently, however, scientists have been finding that long-term use of these fertilizers can cau

15、se damage to the land and even more dangerous, to peoples health.Task 2 Put the four paragraphs in order. ABCD_ _ _ _ Read for the structureTask 2 Find the structure of the passage1.Whats the function(功能) of the first paragraph? A. to explain the topic B. to analyse the topic C. to introduce the top

16、ic2. Which two paragraphs can be grouped together?Para 2 problems Para 3 organic farming Para 4 organic farming methods3. Whats the relationship between Paragraph 2 and Paragraph 3&4?Para 2 Chemical farming causes the problems.Para 3&4 Organic farming _ the problems.solvesPara 1 Topic Why are chemic

17、al fertilizers so popular in farming? .a great way to stop crop disease and increase production.Read for UnderstandingPara 2 Problems How many problems are listed in this paragraph?1.2.3.Problems caused by chemical fertilizersFirstAlsoIn additionDamage _Watercropsanimals, humans the landFruit, veget

18、ables, other foodRead for UnderstandingPara 3&4 SolutionTask 1 What do organic farmers focus on ? They focus on keeping their soil rich and free of disease.Read for UnderstandingRead for UnderstandingPara 3&4 SolutionTask 2 Underline the organic farming methods and their advantages in Para 3&4.Read

19、for UnderstandingTask 3 Retell the organic farming methods with the help of the key information on the blackboard and picturesOrganic farmers prefer using _ as _.natural wastefertilizerRead for Understandingdifferent levels of soilsurfaceundergroundsoilOrganic farmers plant crops to use_.Some crops use the _of soil, followed by other crops that put down _.surfacedeep rootsRead for Understandingcropsgrasssoilplant. between.prevent. from.become a natural. change .put . back into .make it ready for.Read for Thinking1. W