Content: Graphics regular class hours: 1 Teaching preparation:

Teaching objective: 1. Find out the rules in the figure by placing them and express them in letters.

2. By placing graphics, find regular activities and develop the ability of abstract generalization.

Basic teaching process:

One,

First, create a situation

1、

Do you remember the problem of putting a triangle with a stick? Triangles can also be placed like this to display graphics.

Second, explore the law:

Please look at the picture and fill in the form:

Panel discussion:

The number of triangles is 1234 ... the number of rods is 3579. ...

Teaching reflection: it is strange for students to find out the laws in the graphics through placement. This part of the content is the difficulty of teaching. In the teaching process, let students place more, discuss and summarize the law of such a triangle in groups. It works better this way.

Number of triangles

The number of rods is1234 ... n3 =1+25 =1+2+2.

7= 1+2+2+2

9= 1+2+2+2+2

...（

)

Look at the pictures and watches: Look for the relationship between the number of triangles and the number of sticks.

Teachers encourage students to find relationships from various angles, such as figures and numbers, and guide students to find that for every triangle, two sticks are added. This relationship is expressed by formula. Finally, it is represented by letters.

Who can tell how many sticks are needed to put N triangles? what do you think?

Third, the application law:

If (1) put 26 triangles, how many sticks do you need? What should I think?

(2) There are 63 now. How many triangles can you put? What should I think?

Panel discussion:

Group Report: IV. Summary: