Teaching material analysis:

"What is circumference" is the content of the first lesson in Unit 5, Grade Three, Primary School Mathematics, Beijing Normal University Press. This lesson breaks through the difficulties in students' observation and touch activities, and recognizes and perceives the significance of perimeter. On the basis of understanding the circumference, solve the problems about the circumference and cultivate students' inquiry consciousness.

Teaching objectives:

1, through observation and touch, correctly understand the meaning of perimeter.

2. On the basis of understanding the meaning of perimeter, we will use appropriate methods to measure the perimeter of an object or a plane figure.

3. Let students acquire rich perceptual knowledge through activities such as watching, drawing and touching, and let students sublimate perceptual knowledge into rational knowledge in experience and communication activities.

Student analysis:

1, the student is about 8 years old and is very interested in the course of operational mathematics.

2. Students like to participate in the process of knowledge generation and have a preliminary sense of inquiry.

Teaching methods:

1, let students discuss and summarize the meaning of perimeter in touch learning tools and observation pictures, and actively acquire new knowledge.

2. On the basis of perceiving the meaning of perimeter, complete the related knowledge of perimeter independently through screen prompts. Cultivate students' exploration and learning ability.

Teaching preparation:

1, PPT courseware, self-made pictures.

2. Students prepare leaves, trapezoid, rectangle, square, triangle, rope and colored pencils.

Teaching process:

First, introduce new lessons.

Students, what season is it? Autumn is the season of falling leaves and harvesting fruits. The teacher collected pictures of all kinds of leaves from the internet. Let's enjoy them together! (Play the courseware) Are these leaves nice? Do you want to describe their shapes?

Second, explore what is the perimeter.

1, feel the surroundings. (Describe and say)

Please take out a piece of paper, choose a favorite leaf, and draw its outline along the edge of the leaf with a colored pen. Let's start!

2, good! Who wants to show you how to draw? Students can draw a picture on the blackboard.

Please point with a pen and make it clear where to start and where to end.

Is it right? Well, it's clear.

3. Then name the students and say where they started and where they ended.

4. Summary: It seems that no matter where we start, everyone draws a week along the edge of the leaf. Please see (courseware demonstration), the length of this week, we call it the perimeter of this leaf. (Blackboard Title: Perimeter)

5. Let's take a look again. (The courseware is shown in the figure. Can you draw the edge of the picture below?

Please take out your paper, choose a figure you like and draw it with pen and ink. Communicate with each other in the same place after painting. (Note: When checking, pay attention to whether the students have drawn a week, and the courseware shows the wrong and correct drawing methods to deepen the students' correct understanding of the week. )

Just now, the students drew along the edge of the figure for a week. How long is this week? (Student answers) It is the circumference of this figure. How clever! )

Third, connect with reality and perceive the surroundings. (Complete the sublimation from sensibility to rationality)

1, find it.

Can you find an example from us to illustrate what circumference is? Now please work hard at the same table, find it and touch its sideline. (Guidance: floor circumference, desk circumference, textbook cover circumference, blackboard surface circumference, sole circumference. )

2. Who will talk about the result you are looking for? You can point when you speak.

Step 3 measure it.

(1), have you found a lot? It seems that perimeter is everywhere in our life and has a wide range of applications. For example, when we make pants, the tailor will measure your waistline, which is what we usually call waistline.

(2) Now, please estimate how many centimeters the teacher's waist is.

Is the estimate accurate? Who will measure it? (Pay attention to the guidance of measurement methods: how to measure waist circumference) Tell everyone the measurement results.

According to this result, please estimate how many centimeters your waist is.

Measure the cooperation at the same table. Who can tell me how many centimeters your waist is?

Fourth, consolidate practice and deepen understanding.

Summary: Through the previous study, the teacher found that students are good at observing and thinking. Now the teacher will test everyone.

1, please turn to page 45 of the textbook and do the third question.

Think about it, how can we know if they are the same length? (Courseware demonstration class)

2. Measure and calculate the perimeter of the picture below. Overall planning (Question 2 on page 45 of the textbook, courseware shows)

3. Draw a picture. Done independently. (Title 1 on page 45 of the textbook)

Class summary: What did you learn in this class? Please give an example.

Sixth, thinking expansion.

Courseware presentation: Find the perimeter of rectangle and square.