Second, the analysis of test questions

The main teaching process and blackboard writing design of axisymmetric graphic properties in junior middle school mathematics

teaching process

(A) setting questions and introducing new courses

Fold a piece of paper in half, make a hole and lay it flat.

Teacher-student summary: If two figures are symmetrical about a straight line, then the symmetry axis is the middle perpendicular of the line segment connected by any pair of corresponding points. Similarly, the symmetry axis of an axisymmetric figure is the median vertical line of a line segment connected by any pair of corresponding points.

(C) examples of consolidating and deepening the principles

For example: Are the following figures axisymmetric? If it is to point out their symmetry axis.

Teacher-student activities: Students complete the examples independently first, and the teacher explains the examples.

(4) Summarize the homework

Teachers guide students to review the main contents of this lesson and share their views through mutual communication:

What is the concept of (1) median vertical line?

(2) What is the essence of graphic symmetry?

Teacher-student activities: Teachers summarize on the basis of students' communication.

Homework: Do homework after class, find the symmetrical figures around you, mark the symmetry axis and find a pair of symmetrical points.

blackboard-writing design

Special analysis of national defense

1. What is the difference and connection between an axisymmetric figure and an axisymmetric figure composed of two figures? Mathematical professional problems

Reference answer

When two symmetrical figures are regarded as a whole, it is an axisymmetric figure. Divide an axisymmetric figure into two figures along the axis of symmetry, and the two figures are symmetrical about this axis.

That is, an axisymmetric figure refers to a figure; Axisymmetric figure refers to two figures.

2. Please list more than five common axisymmetric figures. What is their symmetry axis? Mathematical professional problems

Reference answer

Circle: countless; Equilateral triangle: 3; Diamond: 2 strips; Square: 4 squares; Rectangular: 2 strips; Regular pentagon: 5; Regular hexagon: 6 bars.