Step 1.Greetings.

设计意图：让学生做好上课的准备。

Step 2. Think about it.

1. What do you know about DNA?

2. What can scientists do with DNA?

设计意图：与学生进行一个简短的对话，进入本课主题。

Step 3. Show students some pictures to let them know something about DNA and the new words in this lesson.

设计意图：通过展示图片让学生了解本课重点单词及DNA的知识。

Step 4. Read the lesson and answer the questions.

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 is related to yours?

设计意图：让学生带着任务读课文。

Step 5. Language Points

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.

Jack sits between Lin Tao and Bob.

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. 他正用小刀切面包。

【注意】 use的形容词是useful，它是由use加后缀-ful构成的。如：

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表示“也”时,通常置于句末，其前用逗号隔开。

【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”。它们通常都位于句末，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 DNA.

除了每对双胞胎之外，每个生物都有它唯一的DNA。

1)except for除……以外，只是

He is a good man except for hot temper.