小学数学第八册教案

垂直

学科目标：

1、  结合生活实际，直观认识相交、交点、互相垂直、垂线、垂足等概念。

2、  能用语言、符号表达两条直线互相垂直。

3、  能根据图形特点或利用工具正确判断两条直线是否互相垂直。

语言目标：

1、能基本听懂教师的课堂用语，会用英语与老师交流。

2、能用英语表达什么与什么互相垂直。

3、会用英语表达一些数学术语：垂直、互相垂直、垂线和垂足等。

Main point：

能够理解互相垂直、垂线、垂足这些概念。

Aids: 多媒体课件、三角尺、练习纸。

Teaching procedures:

一、通过直角，感知垂直：

1、师：If you go to the Forest Park, you don’t  know the way, what can you do ?

   生：I can ask the way.

   生：I can look at the map.

2、Map

 师：Look at this map.What can you see?

生：I can see the Forest Park is near the zhongshan road.

生:：the forest park is near the yulan road.

师：ok,there are some roads intersected to make right angles.

For an example,the north senlin road intersected to zhongshan road.this?

Who can try?

生：yulan road intersects daxue road to make a right angle.

师：now then  how do we prove these roads intersect to make right angles?

生：triangle.

师：yes.now Do pair work.:

(1)    Look for right angles .

(2)    Add the right angles.

(3)    Say which road intersects which road to make a right angle.let’s begin.

师：who can try?

二、画出直角，建立垂直的表象 

1、  师：Please draw a right angle with things on the desk.生画

Which way did you draw?

生：Use triangle.first,draw a line .second, find right angle side,third, draw the other line.this is a right angle.

 生：Use a protractor. first, draw a line, second find 90 degrees, third, draw the other line.

 生：fold ,fold again.

2、  师：Let me draw a right angle with triangle.look.

What do you know about right angle?

 生：it has a vetex and two sides.

生：it is 90 degrees.

师：What’s relation between these two lines?

生：these two lines intersect to make a right angle.

3、  Summary：

师：Yes.When the red line intersects the blue line to make a right angle, the red line is perpendicular to the blue line, the blue line is perpendicular to the red line. So the red line and the blue line are perpendicular each other.

师：who can try?

4、  师：Let’s learn “The perpendicular” in this class.

三、理解“互相垂直”：

1、师：just now we saw some roads intersect to make right angles.now Discuss in small groups:

Who can say which roads are perpendicular each other ?

生：zhongshan road is perpendicular to daxue road.

生：

2、师：What will it change when we lengthen the red line ？the blue line? What will it change?

生：beeline.

师：Are the red line and the blue line still perpendicular after we lengthened the two lines?

生：yes.

师；we can prove.look!are they still perpendicular?

生：yes.

师：now lengthen your sides of righe angles.are they still perpendicular?

生：yes.

3、Summary:

师：When two beelines intersect to make a right angle, these two beelines are perpendicular each other.One is the other one’s the perpendicular.The point of these two beelines’ intersection is the foot of a perpendicular.

师：say by yourself.

4、师：we can use this sign      to  express perpendicular. With your finguer.

师：we can use small letters a and b to express the red line and the blue line .

We can write a   b  ,read a is perpendicular to b.

Or write b    a, read b is perpendicular to a..

师：we can use capital O to express the point of intersection.it means the foot of a perpendicular.

四、巩固练习：

1、    师： Let’s have a judge.yes or no ?

师：first one ,yes or no?why?

2、    师：Let’s do the following orally.

师：say by yourself. who can try?

3、    师：why point M isn’t a foot of a perpendicular?

生：they aren’t perpendicular each other.

师：we can prove with triangle.

五、总结：

 What did you learn this class?

六、拓展练习：