英语教案－Senior 3 unit4 lesson15

高三 Unit 4 Lesson 14

Step 1 Revision

1 Revise the dialogue in Lesson 13, paying special attention to intonation.

2 Check the Ss‘ dialogues.

Step 2 Discussion and presentation

SB Page 20, Part 1. Get Ss to talk about the picture and describe what they can see; Read aloud the questions, then put Ss into groups of four and get them to discuss these questions briefly. Ask different groups for their answers and write these on the Bb. Then say Now read the passage and find out. Allow the Ss enough time to read the text, then put them in pairs and get them to compare their answers. Collect the answers from the class. Answers:

1 It is being built on; it is being lost by the actions of the wind and the rain; land is becoming too salty.

2 You can increase the area of farmland by irrigation; you can build dams and water your fields; you can pump water from low-lying areas; you can develop new plants which produce heavier crops; you can develop new plants which grow in poor soil; you can develop new plants that are less likely to be attacked by pests and diseases.

Step 3 Reading

Ask the Ss more questions about the passage. Let them read the whole passage carefully and answer the questions, working in pairs or small groups. Check the answers with the whole class. This is a good time to deal with any language problems. See if the Ss can guess the meaning of salty, ruin, storage, day by day, etc.

Notes:

a Feed the world: In 1994, Professor Pimentel of Comell University warned of the following problems in providing enough food for the world’s growing population:

* By 2100 the population will be 12-15 billion, or seven times its sustainable level.

* Farmers are abandoning 25 million acres each year because of soil loss or waterlogging.

* The declining fertility of the soil will lower food production by 20% in the next 25 years.

* Topsoil is being lost 40 times faster than it can be replaced.

* Crop losses destroyed by pests have increased four times in the last 50 years.

b It is thought that: Note the use of the passive for introducing an idea.

c For one thing: This phrase is linked to The problem is... in the previous sentence. = One reason why it is difficult to feed the world‘s population is that...

d suitable for growing crops: Point out the structure: suitable +for + -ing