There are many classifications of symmetric figures.

One:

Symmetric figure: If a figure is folded in half along a straight line and the two parts completely overlap, such a figure is called an axisymmetric figure.

Two:

If a graph rotates 180 degrees around a certain point, and the rotated graph can completely coincide with the original graph, then this graph is called a centrosymmetric graph. And this center point is called the center symmetry point.

Three:

Rotationally symmetric figure: a figure rotates an angle around a fixed point and then coincides with the original figure. This figure is called rotational symmetry figure, the fixed point is called rotational symmetry center and the rotation angle is called rotation angle. (The rotation angle is 0 degrees.

How to explain symmetrical graphics to kindergarten children

Teaching goal of beautiful lace: 1. Cognitive lace is the repetition of graphics; 2. Cultivate students' hands-on abilities such as folding, cutting, pasting, drawing and printing, and master production techniques; 3. Cultivate students to dare to think and speak, boldly create consciousness and experience the beauty of lace patterns; 4. Cultivate students' modeling design ability and problem-solving ability; Teaching emphasis: understanding lace patterns.

Which plane figure is axisymmetric?

Rectangular square

isosceles triangle

equilateral triangle

Isosceles trapezoid rhombus

All circles are axisymmetric figures.

Which figures are axisymmetric, not centrally symmetric?

Axisymmetric graphics are: after folding along a straight line, the parts on both sides of the straight line overlap with each other.

A centrally symmetric figure is a figure that rotates180 around a certain point and then coincides with the original figure.

There are straight lines, line segments, two intersecting straight lines, rectangles, diamonds, squares, circles and so on.

Only axisymmetric figures are: ray, angle? Isosceles triangle, equilateral triangle, isosceles trapezoid, etc.

Only the figures with central symmetry are: parallelogram, etc.

Figures that are neither axisymmetric nor centrosymmetric include equilateral triangles, isosceles trapezoid, etc.

Kindergarten space and plane teaching plan

Teaching objectives:

1. Knowledge and skills: Through observation, operation, discussion, appreciation and other activities, students can initially understand the basic characteristics of axisymmetric graphics and understand the axisymmetric phenomenon in life.

2. Process and method: To enable students to understand the meaning of symmetry and axis of symmetry, and to judge the symmetrical figure and draw the axis of symmetry.

3. Emotion, attitude and values: By appreciating the living things and corresponding graphics, we can feel the connection between mathematics and life, so that students can fully perceive the beauty of mathematics and stimulate their love for mathematics.

Teaching Emphasis: Understanding Axisymmetric Graphics

Teaching Difficulties: Understanding the Meaning of Symmetry Axis

Teaching process:

First, create a scenario and import a new lesson:

Do the students still know these plane figures?

Rectangular, square, triangle, circle, parallelogram, (you remember it clearly! )

Today, the teacher led the students to know a new plane figure. (blackboard writing: graphics) Before knowing the new graphics, the teacher asked the students to appreciate a set of paper-cuts: courseware (paper-cuts).

Paper-cutting is an ancient traditional folk art in China and one of the most popular folk arts in China. It has a long history and unique style, and is deeply loved by people at home and abroad.

Do you have anything to say after reading this group of paper-cut patterns?

Let's applaud the great people of China!

Do students like paper cutting?

That teacher will give you some time to cut out your favorite patterns with small scissors and your favorite colored paper to see who can build them quickly and well.

Display: (folding, random, carefully drawn)

Report: Who can tell me how you cut it?

Note: Some of these paper-cut patterns were cut after being folded in half, and some were cut without being folded in half. Can you sort the patterns on the blackboard?

Please observe this set of patterns and see what they have in common.

Both sides are the same size and shape, with a crease in the middle.

The teacher randomly takes a design demonstration and then folds it in half. What can he see? (Only half of the pattern can be seen)

What about the other half?

With the help of the picture in your hand, you can only see half of the pattern, which means that the edges of the pattern are completely coincident.

Let's take another look. (The teacher demonstrates the process of folding and overlapping) Are the edges completely overlapping?

Reveal the theme

A figure whose edges are completely coincident after being folded in half from left to right or folded up and down like this is called a symmetrical figure. Blackboard writing: symmetry

Today, in this class, we will learn symmetrical graphics.

This crease in the middle of the symmetrical figure is called the symmetry axis blackboard: symmetry axis.

We can also draw a line along this crease to represent the symmetry axis of the figure. certificate

Can you find the symmetry axis of these symmetrical figures? The teacher helps draw.

Do you think the symmetry axis has any function?

Ask these students (cut at will, cut after painting) to check whether the patterns they cut are symmetrical.

It's amazing that the students cut out so many symmetrical figures.

Second, practice:

1. Look at the picture and judge:

2. Judge whether the figure in your hand is symmetrical.

Does the teacher also bring some symmetrical figures to the students?

Courseware:

The first category: natural beauty (many animals and plants have their own symmetrical forms)

Animals and plants

The second category: artistic beauty (symmetry is also an important criterion for artists' creation)

Paper cutting, facial makeup, architecture

The third category: balanced beauty: (symmetry is not only beautiful, but also keeps the balance of objects)

Cars, planes

Let's talk about your feelings about symmetrical graphics.

The words on the blackboard: beauty

Three. abstract

Can you tell me which objects around you are symmetrical figures?

Children, can you give full play to your creativity and design beautiful symmetrical figures?

Students, what have you learned in this class? ...

What are the figures that are both central symmetry and axial symmetry?

The figures with central symmetry and axial symmetry are:

Round; circular

A regular polygon with uniform sides.