1, teaching content: what is the circumference, the textbook published by Beijing Normal University, page 45-46, Unit 5, Volume 1, Grade 3 Mathematics.

2. The position, function and significance of teaching content.

The content of this unit includes: the understanding of perimeter, the measurement and calculation of perimeter, the calculation method of rectangle and square perimeter, transportation and mathematics. What is perimeter is the first lesson in this unit. It is based on students' understanding of plane graphics such as triangle, parallelogram, rectangle and square, and learning the perimeter of plane graphics. Through this part of the teaching, students can initially perceive the meaning of perimeter, paving the way for understanding the perimeter and its calculation of various graphics in the future.

3. Teaching objectives

The new curriculum standard points out that through mathematics learning, students can acquire necessary and important mathematics knowledge, basic mathematical thinking methods and necessary application skills to adapt to future social life and further development. Combined with the characteristics of teaching materials and the actual level and psychological characteristics of junior three students, I have determined the following teaching objectives:

(1) Knowledge and skill objectives:

Know the meaning of perimeter and establish the concept of perimeter.

(2) Problem solving objectives:

Combined with specific objects, we can know the circumference through observation, operation and other activities. Can initially measure the perimeter of triangles, quadrangles and other graphics.

(3) Emotional attitude goal:

Through demonstration operation, students' interest in learning is stimulated, and the habit of observation and thinking is cultivated, so that students can achieve the purpose of autonomous learning, participation in learning and cooperative learning.

(4) Mathematical thinking goal:

On the basis of students' full participation in the learning process, cultivate and develop students' multi-directional thinking, and encourage students to measure and calculate the perimeter of graphics in various ways.

4. Teaching emphases and difficulties.

Because the third-grade students' correct understanding of this concept is the basis for future study, the teaching focus of this class is determined as: expressing the meaning of perimeter with concrete things or figures.

Because it is the first time for students to experience the method of calculating perimeter, it is a teaching difficulty to master the method of measuring perimeter.

Second, talk about teaching methods and learning methods.

The teaching of this lesson mainly follows two principles:

1, following the principle of teacher-student interaction. Teachers should be guides, commanders and collaborators in teaching. Teachers should create an active atmosphere in the classroom, ask questions to stimulate students' enthusiasm, be good at guiding and truly implement the new curriculum concept in practice.

2. Students' independent exploration is the main form of group cooperation, allowing students to express different opinions, giving full play to the role of mutual assistance among students, and cultivating students' ability to solve practical problems in various ways.

Third, talk about the teaching process:

(A) to stimulate interest in introduction, perception for a week.

The scenery in autumn is really beautiful! Autumn wind flies in the air with red leaves, and some fall to the ground to become a playground for small insects. Look! Yellow, red and bright colors will have a competition on the leaves. Let's read the rules of the game together! "Bypass the edge of the leaves"

(Design idea: At the beginning of the class, the beautiful autumn scenery was displayed by using multimedia courseware, which quickly attracted students' attention; The dynamic demonstration of interesting pictures of three small insects crawling on leaves greatly stimulated students' interest in studying the crawling route of small insects and effectively helped students perceive the "week" of leaves. )

Son, not only the surface of leaves has a week, but also the surface of many objects. Please find it by your side! Touch the week on your desk, the week on the cover of your math book, and the week on the surface of your pencil box. Touch your rubber surface for a week.

(2) Explore new knowledge and understand "perimeter"

Huang Huang and Hong Hong had a game. Who won in the end? Do you think it's fair? Why? Although it's all a week, the leaves are of different sizes. What is the result? The length of a week is different.

Design thinking: through activities such as "painting", "seeing" and "touching", the appearance of "one week" is further established; Deepen the understanding of "one week". ) blackboard writing week and length final summary:

Perimeter is the length of a circle on the surface of an object. Therefore, the length of the leaf surface is the perimeter of the leaf. The length of the blackboard surface is the circumference of the blackboard surface. The length of a week of the desktop is the circumference of the desktop. The length of a week on the cover of a math book is the circumference of the cover of a math book. The length of the surface of the pencil case is the circumference of the surface of the pencil case. Teacher Li heard a child say that the length of the pencil box is the circumference of the pencil box. Teacher, there are many things here. Can you find out the circumference of these things? You see, there are so many faces in the chalk box, and each face has a perimeter. Be sure to find out which face of the chalk box has a perimeter.

(Design thinking: Start with the familiar objects around students, touch and talk about the perimeter of various object surfaces, and deepen the understanding of the meaning that "the length of the object surface is the perimeter of the object surface". )

Smart children will record in class. Please write this sentence down. The length of the graph week is the circumference of the graph.

(3) Work in groups to explore how to get the perimeter of the figure.

Can you get the circumference of the picture below?

(1), reading activity requirements

Activity requirements:

have a discussion

1. What are the possible measurement methods? What kind are you going to use?

2. Which measuring tools are selected?

3. How to divide the work and cooperate within the group?

Do it.

Actual measurement.

Say it.

1. What measurement method is used?

2. What are the selected measuring tools? What should I pay attention to during the measurement?

3. What is the result of the measurement?

(2) Group activities

(3), the whole class exchange summary

The methods for obtaining the perimeter are:

Count;

Measure a quantity;

Circle first and then measure;

Do math;

(4), consolidate the exercise

1, trace a trace

2. Measure and calculate the perimeter of the picture below.

3. Are the perimeters of the two figures in each question the same? The first network of new curriculum standards

4. compare the perimeters of part a and part b in the picture below.

Design thinking: diversified exercises help students to further clarify the meaning of perimeter, explore ways to compare the length of perimeter, and cultivate the flexibility of students' thinking. )

(5), class summary

Son, what did you gain from today's study? Some children said, I know what the circumference is. Some children said that I learned to measure and calculate the circumference. Some children said that I learned to measure my waistline. You really gained a lot!

Design thinking: talk about the harvest and experience the happiness of success. )

Fourth, write on the blackboard