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教学课题 Lesson 29　DNA—The Story of You 备注
教学目标 【知识目标】 Important words: DNA,blueprint,general,complex,twin,repeat,pattern,identify,related,grandson,granddaughter,instruction Important phrases:in general,except for,be related to,billions of Important sentences: (1)In general,a blueprint is a drawing that shows how to put a house together with many different parts. (2)But building a living thing is far more complex than building a house. (3)Except for some twins,every living thing has its own unique DNA. (4)From your DNA,scientists can identify not only you,but also people who are related to you. (5)Your DNA has billions of instructions that explain why you are the way you are. 【能力目标】 能够用英语向他人介绍自己所知道的有关DNA的知识。 【情感目标】 了解有关DNA的奥秘。
教学 重难点 重点:本课重点单词及短语。 难点:except,except for 与 besides 的用法辨析。
教学过程
◆Step 1　Lead in Show students the picture on PPT. T:Do they look the same S:Yes,they do. T:They're twins.Do you know why they are the same S:Because they have the same DNA. T:Do you look like your mother or your father S:My mother/father. T:Do you know the reason Because your DNA comes from your parents.This is the shape of DNA.What is DNA DNA is short for deoxyribonucleic acid(脱氧核糖核酸).The function of DNA is to store genetic information. 设计意图:通过询问本节课相关问题,引出本课话题——DNA,为下面的学习奠定基础。 与学生进行一个简短的对话,进入本课主题。
◆Step 2　Think about it. What can scientists do with DNA
◆Step 3　Show learning aims. Let the students read the learning aims together.(见课件) ◆Step 4　Learn the new words and expressions. 设计意图:让学生在学习本课时之前,了解本节课的学习目标以及需掌握的单词短语。
◆Step 5　Listening Listen to the lesson and finish the exercises. 1.Where does your DNA come from 2.Is your DNA in every part of your body 3.Generally speaking,a 　　　 is a drawing. 4.　　　 for identical twins,each living thing has its own unique DNA. 【Keys】1.My parents.　2.Yes,it is.　3.blueprint　4.Except 设计意图:通过听听力做练习,提高听力水平,并大体了解课文内容。
◆Step 6　Reading Read the lesson and answer the questions.(见课本P75 Let's do it!1) 1.What is a blueprint 2.Which is more complex,building a living thing or building a house 3.Do some twins have the same DNA 4.Is it possible to change your DNA 5.Whose DNA do you have 【Keys】 1.A blueprint is a drawing that shows how to put a house together with many different parts. 2.Building a living thing is far more complex than building a house. 3.Yes,they do. 4.Yes,it is.In the future,scientists might be able to change our DNA. 5.The DNA of my parents and grandparents. 设计意图:要求学生认真阅读课文,把握课文信息,回答问题,对文章内容有更深层次的理解。
◆Step 7　Language points 1.in general意为“一般而言,概括说来”,通常置于句首,也可以用generally speaking来表示。 2.different为形容词,意为“不同的”,常用于以下结构中:be different from与……不同;be different in...在……上不同。 3.比较级前可以用much,even,still,far,a bit,a little,a lot等词加以修饰。 4.(1)except for“除……以外,只是”,排除的不是同类,表示对主要部分的肯定和对局部的否定。 如:Your article is quite good except for several spelling mistakes. 你的文章很好,只是有几处拼写错误。 (2)except“除……之外”,排除后面的人或物,而且排除的内容和主语往往是同一类。 如:We all went to see our teacher yesterday except Li Ming. 昨天除了李明以外我们都去看我们的老师了。(李明没去) (3)besides“除……之外(还)”,包括该词后面的人或物。 如:We all went to see a film besides Li Ming. 除李明以外我们也都去看电影了。(李明去了) 5.health为不可数名词,意为“健康”,常构成短语in good/bad health,意为“健康/不健康”。 【拓展】(1)healthy为形容词,意为“健康的”,unhealthy意为“不健康的”;keep/stay healthy意为“保持健康”。 (2)healthily为副词,意为“健康地”,eat healthily意为“吃得健康”。 6.not only...but also...“不但……而且……”连接两个相同的成分,也可连接两个分句。连接两个并列主语时,谓语动词和临近主语保持一致;连列两个并列分句时,not only置于句首,通常用倒装结构,也就是说,把not only引导的分句中的助动词或be动词提到主语前面。 设计意图:让学生掌握本课重要知识点。
7.be related to意为“和……有联系,和……有关,与……有亲属关系”。relate为动词,意为“把……联系起来”,常与to搭配。 8.one of the most amazing things意为“最令人惊奇的事情之一”,为“one of the+形容词的最高级+复数名词”结构。其中定冠词the也可使用形容词性物主代词来代替。
◆Step 8　Practice 1.Fill in the blanks with the phrases in the box.(见课本P75 Let's do it!2) in general,except for,not only...but also,related to,even if,the same...as (1)Your homework is quite good 　　　 a few spelling mistakes. (2)　　　 the young 　　　 the old like pop music. (3)Kate's hair is 　　　 colour 　　　 her sister's. (4)　　　,women live longer than men. (5)　　　 many difficulties remain,we can overcome them. (6)Is wealth 　　　 happiness 【Keys】(1)except for　(2)Not only;but also　(3)the same;as　(4)In general (5)Even if　(6)related to 2.Complete the passage with the sentences in the box.(见课本P75 Let's do it!3) Changing DNA Do you know DNA can be changed Have you ever seen a pig with a dog's body Of course not!Pigs and dogs can't have babies together.(1)　　　 But now,scientists can do it.Scientists can take DNA from one kind of animal and put it into another kind of animal.They can design new plants by combining the DNA of other plants.(2)　　　 Some scientists are worried.They say we need to know more about DNA before we start changing it.(3)　　　 But what if the plants are bad for humans,too A.Their DNA can't combine. B.We can make plants that are bad for pests. C.They can even combine the DNA of a plant and an animal. 【Keys】 (1)A (2)C (3)B 设计意图:在掌握了课文中的重点句子和短语之后,做词汇、句子、短文练习,能有效巩固本课所学知识点。
◆Blackboard design Lesson 29 重点单词: DNA,blueprint,general,complex,twin,repeat,pattern,identify,related,grandson,granddaughter,instruction 重点词组:in general,except for,be related to,billions of 重点句式: (1)In general,a blueprint is a drawing that shows how to put a house together with many different parts. (2)But building a living thing is far more complex than building a house. (3)Except for some twins,every living thing has its own unique DNA. (4)From your DNA,scientists can identify not only you,but also people who are related to you. (5)Your DNA has billions of instructions that explain why you are the way you are.
◆Step 9　Exercises Ⅰ.用括号内所给单词的适当形式填空 1.This is the 　　　(identify) hotel that we stayed in last year. 2.Your brothers are people 　　　(relate) to you.
3.Do you know who is the 　　　(own) of the house 4.Your body uses this pattern 　　　(build) itself. 5.You have your own DNA,but it repeats the patterns from your 　　　(parent) DNA. 6.Some health problems come from your family's DNA.　　　(science) can look for these problems in your DNA. Ⅱ.同义句转换 1.Both you and Linda give us a big surprise. 　　　 　　　 you 　　　 　　　 Linda 　　　 us a big surprise. 2.It takes me half an hour to clean up my room. I 　　　 half an hour 　　　 up my room. 3.My book isn't the same as his. My book is 　　　 　　　 his. 4.What do you do with this problem 　　　 do you 　　　 with this problem 5.He can speak Chinese. He is 　　　 　　　 speak Chinese. 6.I don't know how I can build a house. I don't know how 　　　 　　　 a house. 【Keys】Ⅰ.1.identical　2.related　3.owner　4.to build　5.parents'　6.Scientists Ⅱ.1.Not only;but also;gives　2.spend;cleaning　3.different from 4.How;deal　5.able to　6.to build 设计意图:通过练习,让学生巩固本课时知识点。
◆Step 10　Homework 1.Preview the words and expressions in Lesson 30. 2.Write a passage about DNA.Try to tell what it is,where it is from and how you show your parents' DNA.

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