The textbook arranges an example and a question to try. This part is a two-digit division based on students' mastery of integer decimal division, which rounds the number on the divisor to the integer decimal quotient close to him (without quotient adjustment). This part of the content is easy for students to master because there is no need to adjust the quotient in the process of division. Basic knowledge of commercial law is conducive to breaking through difficulties. Therefore, learning the content of this lesson well is the basis of learning division in which divisor is a two-digit number.

According to the concept of "Primary School Mathematics Curriculum Standard", combined with the teaching content, students' knowledge and students' reality, the following objectives are formulated.

1, through learning, enable students to master the quotient of the quartering method in division with divisor of two digits, further consolidate the written calculation method of division, and enable students to correctly calculate this part of the test questions;

2. Cultivate students' knowledge transfer ability and application ability in the process of experiencing rounding method, and cultivate students' observation and comparison ability and induction ability in comparative summary method;

3, combined with activities, let students feel that learning is more important than thinking, and encourage students to form a good habit of thinking seriously. The focus of this lesson is to enable students to flexibly use the rounding trial-and-error method, be proficient in trial-and-error, and make written calculations smoothly and correctly. In the teaching of this course, teachers organize students to carry out activities, so that students can speak, think, discuss, practice and evaluate. In practice, students can learn independently, master knowledge and develop their abilities.

In order to achieve the goal, I mainly arrange the following activities.

First, teach by example and prepare for knowledge.

1, say it. Tell me which integer the following figures are closest to. Say this, let the students find the nearest integer accurately, and prepare for the rounding method. Tell me how many dozens a number has at most (for example, 92 has at most () 30 and so on. ). Let the deskmates communicate with each other first, and then answer orally. Through this lecture, training students' thinking method of trying to do business is helpful for students to try to do business quickly and accurately.

2. Do it. Column vertical calculation (97÷30, 3800÷60), let students talk about the method and results of trial quotient after doing the problems independently. Let students review the calculation method of division in which the divisor is an integer ten, which is helpful for students to use their existing knowledge to migrate. Through this part of knowledge preparation, students can build strong support for learning new knowledge independently. Let students feel the thinking direction of learning new knowledge.

Second, the exploration of Example 4.

The teacher gave an example of 4: 97 ÷ 32 by changing the review question 97÷30, and encouraged the students to try it themselves. Tell the students next to you what you think of computing, and then tell the whole class. In practice and communication, let the students find that it is better to try business when 32 is 30. Encourage students to try the newly discovered quotient method: 209 1÷5 1. After solving the problem, the students will talk about the method of quotient and the calculation results.

By changing numbers and giving examples, let students try to do it, let them know the connection point between old and new knowledge, try to solve problems purposefully and directionally, and use the existing knowledge to migrate, so as to find the trial-and-error method in solving problems: the divisor can be used as a close integer to try the quotient. Feel the joy of learning in trying to succeed. Encourage students to try the business test method immediately, extend their interest in learning, and let students understand and master the rounding business test method. Then organize students to compare the topics they have just learned with those they have already learned, and let them talk about similarities and differences. By comparison, we can find the' growing point' of new knowledge, and students can further realize that divisor is the division of two digits, and they can try to quotient divisor into an integer close to it. Cultivate students' ability of observation, comparison and expression.

Third, use knowledge.

1, tell me that the divisors of the following questions are dozens of test quotients. After the teacher shows the questions, let the students talk at the same table first, and then answer them orally. Through this exercise, the whole class can talk about it, so that students can further master the test method of four rooms.

2, combined with the situation to calculate: the teacher shows the three problems related to this part of the calculation in one step, so that students can solve the calculation. Through this kind of exercises with examples, let students use the method of "four skills" in calculation, let students realize that calculation problems are everywhere in our lives when solving problems, let students feel that mathematics is everywhere in our lives, and let students establish the idea of learning mathematics well.

3. The teacher creates a situation: Teacher Wang takes 500 yuan money to buy toys, each robot is 2 1 yuan, and each bear is 32 yuan. What questions can you ask and do the math? Let students discuss and answer in groups, let students answer questions with knowledge, encourage students to have various results, cultivate students' divergent thinking, cultivate students' interest in learning, and let students realize the usefulness of mathematics.

In this lesson, after building a knowledge base for students to explore new knowledge, students are allowed to try independently, and it is found that rounding is the trial business method, which shows that students are the main body of learning and teachers are the organizers and guides of learning, so that students can learn knowledge and develop their abilities in a relaxed teaching environment.

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