Through practical activities, we can deepen our understanding of the meaning of rectangle, square and figure perimeter, and further master the calculation method of rectangle and square perimeter.

2. In the process of operation practice, exchange and discussion, and total solution, cultivate innovative consciousness, and develop the ability of mathematical thinking and cooperative communication.

3. Cultivate students' love for mathematics.

Teaching emphasis: master the calculation method of rectangle and square perimeter.

Teaching difficulty: master the calculation method of rectangle and square perimeter.

Teaching preparation: wall charts, learning tools and multimedia courseware.

Teaching process:

First, create a situation to stimulate interest introduction. ?

Dialogue: Students, before class, each group is assigned a learning tool basket. Please look at what's in this learning tool basket. Can you tell the teacher? Today, the teacher and his classmates will use these learning tools to further explore the perimeter of some plane graphics. Show me the topic: What is the circumference?

Second, practice solving problems?

1. Spell it?

(1) Please take out six squares with a side length of 1 cm and put them together to see which shapes you can spell. Students operate and teachers patrol. Students interact and communicate. Think about the circumference of your puzzle. Students operate, report and communicate.

2. comparison?

(1) Talk: Students worked out the perimeters of different rectangles and squares by themselves. The teacher has two pictures here (the last two pictures in the multimedia display textbook). Have the students seen such figures? Let's estimate first: which picture has a longer week? Please confirm your guess. Students try to measure and calculate, and communicate in groups. The teacher wrote the roll call report on the blackboard. ?

(2) What is this figure (rectangle) and what is its circumference? Is its perimeter equal to the perimeter of the two numbers just now? Compare these three numbers and tell me what you find.

3. Draw a picture. Dialogue: What is the circumference of a rectangle? Do you know the length and width of this rectangle in centimeters? Let's discuss in groups and see what kinds of situations there are. Can you draw these rectangles? If the circumference of a square is 20 cm? Can you draw this square? ?

Measure and show two pictures in the textbook. What are these two pictures? Can you point out their boundaries? Talk to your deskmate. (In the second picture, please make sure that the circumference is the circumference of a circle, which has nothing to do with the pattern inside. ) Can you estimate the perimeter of these two figures? Can you check it? How are you going to verify it? Work together at the same table to measure the perimeter of two figures. (In the second picture, let the students measure with a soft cord. Pay attention to let students talk about measurement methods. )?

Third, the class summarizes. What do you know about the perimeter through the four activities just now?