2．Discussion to get the students to understand what they are 1earning better．

　　Teaching Aids：

　　1．acomputer

　　2．a courseware

　　3．a tape recorder

　　Teaching procedures:

　　Step I Greetings and Revision

　　Greet the whole class as usual．

　　T：In the last period。you were told to make sentences with the useful words and expressions in the text．Have you got prepared?(Ss：Yes．)Now read the sentences to us．Volunteer!One student，one sentence．

　　Sa：make attempt to do sth．

　　They made no attempt to escape．(at escaping)

　　Sb：classify

　　The books in our school library are classified according to subject．

　　Sc：group

　　Group together in two!

　　Sd：identification

　　He carries identification with him at all times when he is out．

　　Se：promote

　　He works to promote the friendship between the two countries．

　　Sf：privilege

　　They fight against privilege in order to create a fairer society．

　　Sg：cosy

　　He lives in a nice cosy little house．

　　Sh：have an appetite for

　　The enemy had no appetite for the fight．

　　Si：appoint

　　He was appointed minister to a foreign country.

　　Sj：calculate

　　The scientists caculated when the spaceship would reach the moon with a calculator． Sk：on a large scale

　　The work of reforming industry carried out in all provinces on a large scale．

　　Sl：involve

　　The case involved several leaders．

　　Sm：accumulate

　　He accumulated a fortune by investing wisely．

　　Sn：abandon

　　He found a baby abandoned by his parents.

　　Step II Preparation for Reading

　　T：So much for homework．Now open your books and turn to Page 169．Let’s read the new words and expressions of this period．Who will read them to us?

　　Sl：I’ll try．

　　(Teacher asks some students to read the new words and expressions．While reading，let other students correct the mistakes made by the students．Then play the tape to get the students to fol1ow．Teacher may give brief explanation

　　about their usages when necessary．)

　　StepⅢ Fast-reading

　　T：You’ve learnt something about Carl Linnaeus。Daniel Solander and Joseph Banks in the text we’ve just studied．And you’ve read about Michurin and Darwin．Today，we’ll learn about another two scientists Gregor Mendel and Gote Turesson．What did they do? What contribution did they make?After we’ve learnt the passage．I’II sure you’11 have a clear idea．

　　(Show the following on the screen．)

　　Now read the text fast and try to grasp the main idea of the text as much as possible. Then find answers to the questions on the sceen.

　　Answer the following questions:

　　1．What was Charles Darwin’s hobby when he was young?

　　2．What led Darwin to write his famaous book“On the Origin of Species”?

　　3．Who founded the science of genetics?

　　4．Who made contribution to the improvement of the output of crops according to the text? (Students begin to read the taxt. After a few minutes, teacher says the following) T：Have you finished?

　　Ss：Yes，we have．

　　T：Now give us the answers, please. One student，one question．

　　Sb：1．When he was young, Darwin enjoyed doing all kinds of experiments and studying physics, chemistry and later botany was his hobby.

　　Sc：2．When he was twenty-two years old，he was invited to take part in the scientific expedition on the five-year voyage led him to write his famous book：On the Origin of Species

　　Sd：It was the research work of Mendel that gave birth to the science of genetics.

　　Se：Mendel’s genetics and Turesson’s findings are both important to the output of crops． T：What you said is right. Thank you for giving us such good a

　　StepⅣReading and Comprehension:

　　T：(Show the following on the screen)

　　Now let’s read the text again and discuss the questions on the screen. Pairwork or group work．

　　1．The research of Charles Darwin, Gregor Mendel and Cote Turesson is like pieces in a puzzle that show a complete picture when put together.

　　(1)What did Darwin discover about bird species in Galapagos?

　　(2)What did Mendel observe in his experiments with peas?

　　(3)Looking at wild plant species in Sweden，what did Turesson discover?

　　2．Complete the following sentence．

　　Darwin’s discoveries in Galapagos were based on differences______wild species，while Turesson’s observations showed that there are stable varieties___wild species．

　　3．That soil conditions are important to the output of crops was known more than 2000 years ago．Why are Turesson’s discoveries still important to agriculture then? (Teacher goes among the students and joins the students in their discussion．)

　　T：(After some minutes’discussion．)Now give us your answers，please. Who will answer the first question?

　　Sf：He found 13 kinds of findes，related to each other in the structure of their beaks，tails，shape of body and colour of their feathers．The most curious fact was the differences in the size of the beaks．This could only be explained from the differences in habitat and source of food．The birds with broad beaks would eat hard seeds，while the birds with smaller beaks would eat soft seeds or insects．

　　T：Please give us the answers to the second question．

　　Se：He found that many characteristics were passed on from one generation to the next without influence by the environment．

　　Sh：I'll answer the last question of Part 1．He found evidence for the existence of stable varieties within species in nature．He showed that differences between plants of one species occurred as a result of the environmental conditions in their habitat．

　　Si：I think，in Part 2，for the first blank，we should fill in the words“of different，，and the second，“of the same’’．Am I right?

　　T: What do you think, Sj?

　　Sj：I think he is right．

　　T: For the last question, what are your opinions?

　　Sk：Soil conditions are important to the 0utput of crops．But that is one side of the question．The research by Darwin, Mendal and Turesson shows that both genetics and the environment are important to plants．If we don’t have good seeds，good soil conditions are not enough for us to improve the output of the crops．Am I right?

　　Ss：We agree with you．