冀教版九年级下册英语《Lesson 10: What is DNA?》精品教案

桂馥兰香

Lesson 10: What is DNA?
Teaching Content:
Mastery words and expressions: generally, twin, clone, not only…but also
Oral words and expressions: blueprint, identical, egg, identify
Teaching Aims:
1.Know how to write a passage on science.
2.Learn something about DNA.
3.Know more about our body.
1.掌握的词汇及短语
generally, twin, clone, not only…but also
2.识别的词汇短语
blueprint, identical, egg, identify
Teaching Important Point:
1.Master the words and expressions of this lesson.
2.The ability and inability.
3.The use of coordinating conjunctions.
Teaching Difficult Point:
The use of DNA.   
Teaching Preparation: pictures
Teaching Aids: flashcards, audiotape, pictures   
Type of lesson: new lesson
Teaching Procedure:
Step1.Lead in the text by discussing what DNA is. Divide the class into several groups. Then talk about the subject for several minutes. Then one of the groups presents their opinions in front of the class.
Step2. Listening task:
Listen to the tape and fill in the blanks with the correct words you hear.
1.Generally speaking, a ______ is a drawing.
2.______ for identical twins, each living thing has its own unique DNA.
Play the tape once. Then let the students try to finish the task in class in oral.
Step3. Reading task:
Read the text quickly and answer the following questions:
1.Where does your DNA come from?
2.Is your DNA in every part of your body?
Finish the reading task in class in oral. Try to get more information about the text at the same time.
Step4. Read the text again. Find the sentences with the new words. Try to create situation about the new words. Then make sentences with the new words. If someone can make a whole story with the new words that we learn in this lesson, the teacher must encourage her.
The sentences with the new words:
Generally speaking, a blueprint is a drawing.
Identical twins are two children that grew from the same egg.
They are clones.
From your DNA, scientists can identify not only you, but also people related to you.
Step5.Let some students tell some details about the text.
What is DNA?
Where is your DNA from?
What is DNA used for?
二、重点语句分析：
1. Are there differences between you and them? 你和他们之间有什么不同吗?
【辨析】：between与among
between常用于两者之间，among一般指三者或三者以上，如果指三个以上的人或物的每两个之间时，仍然要用between。
Switzerland lies between France, Italy, Australia and Germany. 瑞士位于法国，意大利，奥地利及德国之间。
They live among the mountains. 他们住在群山之中。
I was among the crowd. 我处在人群中
2. You use it to build a house.你用它来建造房子。
use的用法
use…to do sth. 用……做某事
He is using a knife to cut bread. =He is using a knife for cutting bread. 他正用小刀切面包。
Use your eyes to look and don’t use your hands to touch. 用眼睛看而不用手摸。
It is no use doing (to do). 做……是无用的（无益的）
It is no use crying over spilt milk. 不要为打翻的牛奶哭泣。（覆水难收）
【注意】
use的名词和动词同形，但要注意两者的读音/ju:z/是动词的读音，而/ju:s/是名词的读音。useful是形容词，它是由名词use加后缀-ful构成的。如：
What’s the use of this? 这个有什么用途？
Is the fridge very useful? 这台冰箱很有用吗？
3. DNA is a pattern, too. DNA也是一种模型。
too也
too表示“也”时通常置于句末，其前用逗号，其后用句号。如：
I have seen the film, too. 我也看过那部电影。
【辨析】：too与either
too与either都表示“也”，其区别是too用于肯定句，表示“也”；either用于否定句，表示“也不”。他们通常都位于句末，其前用逗号隔开。如：
He has a sister, too. 他也有个小妹妹。
He doesn’t have a knife, either. 他也没有小刀。
4. Except for identical twins, each living thing has its own unique DAN. 除了每个双胞胎之外，每个生物都有他唯一的DNA。
1)except for除……以外，只是
He is a good ma except for hot temper. 除了脾气暴躁外，他是个好人。
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)【辨析】：every与each
every与each都可与单数名词连用，且意义相近，表示“每个”，然而every与each并不完全一样，every强调整体概念，each则表示个体概念。如：
Each day is better than the one before. 一天比一天好。
Every player was in good conditions. 每个运动员都处于很好的状态。
如果不特别强调某一意义时，every和each可以互换。如：
We want every child to succeed. 我们希望每个孩子都成功。
Each child will find his own road to success. 每个孩子都会找到他个人的成功之路。
each可以指两个或两个以上的人或东西，every却不能指两个，只能指三个以上的数量。如：
Each sex has its own physical psychological characteristics. 男女各有其身体上和心理上的特点。（不能说every sex）
另外，如有其它限定词同时修饰中心词，each可作代词用each of的形式，而every则只能用限定词。如：
Each of my parents gave me presents for Christmas. 过圣诞节是我父母每人都给了我礼物。
3)own的用法
adj. 自己的（用在所有格后面，加强语气）
Now ask the same question about your own teachers. 现在请向你自己的老师问同样的问题。
She makes all her own clothes. 他所有的衣服都是自己做的。
vt. 有；拥有
Who owns the bike? 这辆自行车是谁的？
【友情提示】：
owner n. 所有人；物主
He is the owner of the house. 它是这座房子的主人。
The owner of the shop came to see what was the matter. 店主人走过来看看发生了什么事情。
5. From your DNA, scientists can identify not only you but also people related to you. 在你的DNA中，科学家们不但能鉴别你，而且也能鉴别和你有关系的人。
1)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。not only …but also…连接两个并列主语时，谓语动词和后面助于保持一致；not only …but also…连列两个并列分句，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提到主语前面。
He likes not only English but also math. 他不仅喜欢英语，而且喜欢数学。
Not only you but also I am a teacher. 不仅你而且我也是一名老师。
Not only does he work hard, but also he is very clever. 他不仅工作认真，而且很聪明。
2)relate to涉及，有关
The story related to the Second World War. 故事讲的是第二次世界大战的事情。
I have a book relating to the Autumn Harvest Uprising. 我有一本关于秋收起义的书。

Step6. Come to “LET’S DO IT”.
Finish the task with a partner. Find the things about you that show your parents’ DNA. Talk about if for a while. Then let some volunteers come to the front to talk about the subject.
Step7.Homework
1.Finish off the exercises in the activity book.
2.Go on the next reading in the student book.
Summary:
You look like your father or your mother. That identifies the DNA of your body from your parents. DNA is very fascinating. Each living thing has its own unique DNA. Try to find more ways to use the DNA in many fields. Discuss the use of DNA in this class. Make full use of it to help more people in the world in more fields.
练习
Ⅰ. Fill in the blanks with proper prepositions or conjunctions:
1.Do you know the answers ________ the questions?
2.DNA is ________ a blueprint.
3.You composition is quite good except ________ a few spelling mistakes.
4.Are you friends related ________ you?
5.Are your arms long ________ short?
6.Your bones have the same DNA _______ your skin.
7.ou have your own DNA, but it repeats the patterns ________ your parents’ DNA.
8.Some health problems come ________ your family’s DNA. Scientists can look _______ these problems in your DNA.
Ⅱ.Fill in each blank with the proper word from the brackets:
1. This is the __________(identify) hotel that we stayed in
      last year.
2. The two babies are __________(twin).
3. June first is ___________(child) Day.
4. Your brothers are people _________(relate) to you.
5. We should eat _________(health) food.
6. Do you know who is the _________(own) of the house?
7. A blueprint is a ____________(draw).
8. Your body uses this pattern to build __________(it).
9. You have your own DNA, but it repeats the patterns   
     from your __________(parent) DNA.
10. Some health problems come from your family’s DNA.   
      _________(science) can look for these problems in your DNA.
Ⅲ.同义句转换，每空一词：
1. Both he and she are coming to the party.
     ____ ____ he ____ _____ she _____ coming to the party.
2. Tom draws well. Linda draws well, too.
    Tom draws well. _____ ________ _______.
3.Dad’s eyes are not very big. Mine are not very big, either.
    Dad’s eyes are not very big. ________ _________ ______.
4. Sometimes they can help you before you fall ill.
    Sometimes they can help you before you _________ ill.
5. Lucy is as old as Lily.
    Lucy has _______ _________ age as Lily.
6. We all went to the park, but Jenny didn’t go.
    We all went to the park ___________ Jenny.
7. John is from Canada.     John ______ from Canada.
Ⅳ.根据汉语意思完成句子，每空一词：
1.你穿多大号的鞋？
  ______ _______ shoes do you wear?
2.我们用蓝图建造房子。
We _______ a blueprint ______ _______ a house.
3.除了窗子小外这座房子很漂亮。
The house is beautiful ______ _____ the small windows.
4.你的头发和皮肤有同样的DNA。
Your hair has ______ _______ _______ _____ your skin.
5.她不但会唱歌，而且会跳舞。
She can _____ ______ sing ______ ________ dance.
6.每一个生物都有自己独特的DNA。
  ______ _______ ______  _______ its own unique DNA.
7.昨晚他去看电影了，我也去了。
He went to see a film yesterday evening. ____ ____ ____.