Teaching content: Examples 2 and 3 on page 99- 100 and the corresponding "do-do" questions, with 23 exercises 4-8.

Teaching purpose:

1. Make students learn the calculation method of fractional division with divisor as integer.

2. Understand the relationship between the calculation rules of fractional division with integer divisor and integer division, and promote the transfer of learning.

Teaching process:

First, review.

The teacher showed the review questions:

The teacher asked first: divisor is a fractional division of integers. What should we pay attention to when calculating? After the independence, let the students talk about how to deal with the zero in the middle of the quotient when doing the second question. What are the similarities and differences between the calculation method and integer division?

Second, learn new knowledge.

The teacher first asked the students to list the formulas according to the meaning of the questions, and then calculated them vertically. When the students calculated that 36 divided by 9 was not enough quotient L, the teacher asked what to do. Group discussion.

Guide the students to answer: 36 divided by 9 is not enough quotient 1, you can add it according to the decimal point. To the right of 9, the attribute that the decimal size will remain unchanged in the future is added. Divide it into ninety tenths. 90 over ten divided by 36 quotient 0.2. Since the dividend 1 17 is an integer and the decimal point is not written, it is necessary to write the quotient 2 digits after the decimal point on the right side of quotient 3.

After finding the quotient in the tenth place, there is still one tenth of 18, and one tenth of 18 divided by 36 is not enough. What should I do? (Not enough quotient 1 is one tenth. Take one tenth of 18 as the number of the next unit, add 0, it is 180%, and then continue to divide. )

After the calculation, let the students talk about the calculation process. Teachers also wrote on the blackboard:

The teacher explained that there is no remainder at the end of fractional division, which is called division.

2. Do the following questions on page 99.

Let the students finish these two questions independently, and the teacher will help the students with difficulties individually.

3. Summarize the calculation rules of fractional division with integer divisor.

The teacher asked questions. Last class, I studied the example 1 and summarized the calculation law of fractional division with divisor as integer. (The divider is a fractional division of integers, which is removed according to the law of integer division. The decimal point of quotient should be aligned with the decimal point of dividend. )

The teacher pointed to the blackboard and asked, Look at the calculation process of Example 2. What else do you have to add? (If there is a remainder at the end of the dividend, add 0 after the remainder and continue the division. )

The teacher asked a student to repeat the two parts together and explained that this is the calculation rule of fractional division with divisor as integer. Ask students to read the calculation rules of the textbook 100 page silently.

4. Study Example 3.

Teacher's blackboard example 3. What are the characteristics of dividend and divisor?

The vertical question of example 3 on the teacher's blackboard asks, what will happen to the chamber of commerce when the integer part of the dividend is less than the divisor?

Not enough quotient 1, how to write quotient vertically? Think about it. What should we do when the quotient is not 1 in integer division? (Write 0 on the divisor, that is, the quotient bit, and use 0 to occupy the position. )

We combine the digits of the integer part of the dividend with the decimals into 16 decimals. Is it enough? How to write business? (One tenth of the quotient 1 is still not enough, so you should add a decimal point to the right of the unit quotient 0, and then write 0 in the decimal place. )

Imagine the dividend as 169% and then divide it by 26, which is very similar to the previous example. Do it yourself. After the students finished speaking, the teacher asked: under what circumstances is the highest bit of quotient in fractional division 0? (When the dividend is less than the divisor, the integer part is not enough to quotient 1. You should first write 0 in the quotient unit, and then divide it after the decimal point. In the future, except for the one that is not quotient 1, you should write a zero placeholder on that one. )

The teacher asked the students to check whether the calculation of the problem was correct by multiplication.

5. Do the problem on page 100.

Question 1, let the students finish it independently, and the second question should be checked by multiplication. When revising collectively, we should write down the vertical mistakes.

Question 2. Ask the students to discuss in groups after reading the questions. After the discussion, please ask the representatives of several groups to tell the results of the discussion. Teacher guidance. Students complement each other and express the following meaning: as long as the dividend is less than the divisor, the unit of quotient is not enough, and the quotient obtained by this division is less than 1.

Question 3, let the students carefully examine the questions and correct their mistakes. When correcting collectively, let the students talk about the reasons for making mistakes and the reasons for correcting them. You can also show the mistakes in doing the problem 1 for students to discuss and correct.

Third, consolidate the practice.

1. Do Exercise 23, Question 4.

Let the students finish it independently and then revise it collectively.

2. practice three small questions in the first line of question 5 on the 23rd.

Let the students finish it independently. When revising, typical mistakes should be analyzed to find out the reasons.

3. Do Exercise 23, Question 7.

Fourth, summary.

The teacher asked the students to repeat the calculation rules of fractional division with divisor as integer according to the calculation process of Example 3. Then ask the students to say what dividend is smaller than divisor. What should I pay attention to when calculating? (The unit of quotient is not enough quotient 1, so you should write 0 on the unit of quotient first, and then divide it after the decimal point. )

Verb (short for verb) homework

The second line of question 23 exercises 3 questions 6 questions 8 questions.