Teacher: Students, please look at the pictures carefully. The teacher made an animation of an elephant and an ant playing wrist wrestling. At the beginning of the game, the ants were defeated and the whole class laughed. )

Teacher: After laughing, you should think it over. Is this competition fair?

Health: unfair.

Teacher: Why?

Health: Their strengths are too different. One belongs to the heavyweight and the other belongs to the lightweight.

Teacher: How do you know who is lighter and who is heavier?

Health: I can see it with my eyes.

Teacher: You are very observant. Anything else?

Health: You can use weighing scale to measure their weight and compare them.

Teacher: Your method is very original. Have you ever seen a scale? The teacher deduced the unit of weight-kilogram with the help of the students' existing experience. )

2. Questioning teaching cases-in the teaching of "Understanding Circle"

The teacher demonstrated the picture of "Bear Race". Let the students guess whose car makes people feel comfortable.

Health 1: Of course it belongs to the puppy, because its cart wheels are round.

Health 2: The wheels of the bear's cart are square, so people will feel very bumpy and uncomfortable sitting on it.

The question is: Why are all the wheels round? What are the characteristics of a circle?

3. Problem-solving case: peach removal-divisor is a pen division of one digit.

(1) Demonstration example: Calculate 48÷4

(2) Teacher's question: What would you do if you were asked to work out this problem with a pen?

(3) Students' autonomous activities. After a few minutes, no students found the basic method.

(4) Teachers don't interfere, but organize students to have group discussions. After a few minutes, no students found the basic method.

(5) Teachers should teach themselves the basic calculation methods.