Oral notes of integer ten and integer hundred divided by one

Talking about teaching content: the textbook is on 48-49 pages, including example 1, example 2, "Try it" and "Think about it and do it". Example 1 Divide the bishop's integer 100 by one, and Example 2 divides the bishop by hundreds and tens.

Say teaching material analysis: This part teaches integers (including hundreds) and integers divided by one digit (expansion of division in the table). When two digits are divided by one digit, the first step is to divide the number on the tens of digits by one digit, and now it is to calculate the integer ten divided by one digit; When three digits are divided by one digit, the first step is to divide the number on the hundred digits by one digit, that is, divide the whole hundred digits by one digit; If the number on the 100-digit divisor is less than the divisor, divide the divisor by the number on the 100-digit and 10-digit divisor, that is, divide the 100-digit and 10-digit by one digit. Therefore, the logical basis of oral arithmetic of integer ten (including hundreds and dozens) and integer hundred divided by one digit (the extension of division in the table) should be the teaching of writing two or three digits divided by one digit.

Learning situation analysis: In the first teaching example, considering that students already have the experience of addition, subtraction, multiplication and division of an integer decimal digit and the relevant intuitive support in the scene diagram, no specific calculation method is presented, but students are guided to communicate on the basis of independent exploration, showing the diversity of algorithms in communication, and choosing the appropriate algorithm in the comparison of various algorithms. The follow-up attempt is to ask students to calculate the problem of dividing the whole hundred by one digit orally and guide them. In the second example, the pencil ratio is still chosen as the learning material for the oral calculation problem of dividing 100 and 10 into one digit, but the conditions and problems are presented in the form of text narration, which leads students to break away from intuition and think on a relatively abstract level by combining the division in the table and the existing oral calculation experience of dividing 100 and 100 into one digit. This arrangement not only reflects the teaching requirements of different levels, but also helps students to understand the basic principles and processes of oral calculation more thoroughly and gradually improve their thinking level.

Tell the teaching objectives:

1. After exploring the oral calculation method of integer ten and integer hundred into one digit, I can actively understand and obtain the oral calculation method of integer ten and integer hundred into one digit, and I can calculate the number correctly.

2. In the process of exploring the algorithm, we can use the existing knowledge to elaborate ideas and exchange algorithms, develop simple thinking skills such as analysis and reasoning, and accumulate experience in exploring new knowledge and related calculations by using the existing knowledge.

3. Experience the successful experience of the exploration algorithm, establish self-confidence in learning mathematics, and further feel the application of mathematics in solving practical problems.

On the key points and difficulties in teaching;

1. The oral calculation method of integer divided by one digit. 2. Understand the oral calculation of integer divided by one digit.

Teaching method: The new lesson is introduced by multiplying two or three digits in the review table by one digit and multiplication and division, which has strong knowledge transfer, and then the new lesson is taught through three levels. For example, 1, students should look at pictures and think of various algorithms. Pay attention to let students know their own thinking process, remind them to listen actively and consider understanding ideas different from themselves, but don't rush to let them compare the advantages and disadvantages of different algorithms, because letting students choose their own algorithms in communication is conducive to deepening their understanding of basic algorithms. The second level is to give it a try, so that students can finish it independently with their understanding of the example 1 and talk about the thinking process. The third level is the teaching of Example 2, which is the oral calculation of dividing hundreds of tens by a number. Through communication, the idea and method of oral calculation are highlighted: 120 is regarded as 120 divided by 3 to get four tens, which is 40, or 12÷3=4, and so on to 120 ÷ 3 =

Oral arithmetic learning method: after understanding various algorithms at three levels, let students sum up a relatively simple oral arithmetic method of dividing whole ten (including hundred) and whole hundred into one digit, that is, as the corresponding in-table division, adding one or two zeros at the end of this quotient and dividing whole ten into one digit by in-table division has at least four advantages: first, it is easy to think and calculate, which reduces the difficulty; Second, it is similar to the previous oral arithmetic methods of adding and subtracting integers (100) and multiplying integers (100) by one digit, which facilitates the internalization of knowledge and forms a good cognitive structure with students; Third, there is room for further migration after this method; Fourth, this method is conducive to the pen calculation of dividing two or three digits by one digit. Generally, the number on the tenth digit (hundred digits) of the dividend is divided by one digit first, that is, the tenth digit (hundred digits) is divided by a few, that is, the tenth digit (hundred digits) is divided by a few, so the final calculation is the corresponding intra-table division.

Talking about the teaching process:

First, review old knowledge and introduce new lessons.

2x3=？ 20X3=？ 200x3= 40×3=

Tell me how you calculate by mouth. Let's look at another group. Will you shut up? If yes, tell me about your thinking process.

6÷3=? 60÷3=? 600÷3= 120÷3=

This is what we are going to learn today, written on the blackboard: whole ten (including hundreds and dozens) and whole hundred divided by one digit.

(Design intention: It involves the oral calculation of integer ten and integer hundred and one digit and the review of multiplication and division in the table, and further migrates to the oral calculation of integer ten (including hundred) and integer hundred divided by one digit.

Second, explore the algorithm and summarize the algorithm.

(a) to explore the whole ten, the whole hundred divided by one digit.

1. Analyze the conditions and ask questions.

(1) Show the situation map. Let the students talk about the conditions and problems in the picture in an orderly way. What mathematical information do you get from the picture? Students report the observed information: give 60 pencils to 3 good friends. (2) Can you ask a math problem? Student: How many cigarettes does everyone have? (3) Can you make a formula?

(4) The teacher answers the blackboard formula according to the students: 60÷3=

2. Explore independently and try to calculate

(1) Question: Can you calculate 60÷3=? Really?

(2) Independent inquiry: ① You can draw a picture with the help of a stick; (2) you can write your own ideas on the homework paper; (3) It can also be calculated by formula on the worksheet.

(3) Students try to calculate and teachers patrol for guidance.

3 Interactive communication

Method 1: According to the addition, because the sum of three twenties is 60, 60 divided by 3 equals 20.

Method 2: Splitting: Divide 6 bundles of sticks into 3 parts, each with 2 bundles, and the quotient is 20.

Method 3: According to the composition of numbers, imagine 60 as six tens, and these six tenths are in threes, each of which is two tens, which is 20.

Method 4: analogy by division in the table: because 6÷3=2, 60÷3=20.

(3) Summary: Children are so smart that they all have their own different algorithms. No matter whether it is divided into sticks or formulas, six tens are divided into three parts equally, and each part gets two tens, which is 20. Please look at the blackboard and talk about this algorithm.

(4) Remind students to complete the numbers and unit names behind the formula and write a sentence.

? 4. Try to migrate and form an algorithm.

(1) Try it: If 60÷3=20, then 600÷3=? ? Can you calculate?

(2) Named student communication algorithm: ① 600 divided by three gets 200,200. ②6÷3=2,600÷3=200。

(3) Comparing 6 ÷ 3 = 2,60 ÷ 3 = 20,600 ÷ 3 = 200, what do you find? How to calculate integer and integer divided by one digit? Summary: the calculation of integer ten digits and integer divided by one digit can be calculated according to the division in the table, and then one or two zeros are added at the end of the quotient.

5. Practice consolidation and improve the algorithm.

(1) According to this algorithm, please finish it quickly. Would you like to do 1 problem?

(2) Independent calculation and collective correction.

(b) Explore hundreds of dozens divided by single digits.

1. Question dialogue: 60 pencils were successfully solved and distributed to three good friends, each with 20 pencils. Tu Tu children also thought, if there were 120 pencils, how many pencils would each person get if they were distributed to three good friends on average?

2. deskmate communication algorithm: requirements: please ask one child to speak first and the other child to listen carefully; Then let the children judge and supplement the communication algorithm; Two people at the same table have finished communicating. Please say "sit up straight".

3. Collective communication ① 12÷3=4, 120÷3=40. ② 12 Divide ten by three to get four tens, which is 40. Note: Here we calculate 120 as120. Follow-up: Is the calculation method of dividing hundreds and tens by one digit the same as that of dividing tens and hundreds by one digit just now? (Summary: If you divide hundreds of tens by one digit, you can regard the dividend as dozens of tens, which can be calculated as the corresponding division in the table, and then add a 0 after the calculated quotient. )

4. Show what you have learned (1)? 27÷3= 45÷5= ? 30÷6=? 270÷3=? 450÷5= ? 300÷6=? (It is emphasized here that 300 is to divide 30 tens by 6 to get 5 tens, which is 50. )

Third, consolidate practice (think about it and do it)

1. Question 2: Students can finish it independently first, and then organize communication. When communicating, you can choose a few questions, let them talk about the process of oral calculation, and further highlight the basic calculation methods.

? 2. Question 3: Students independently complete and collectively revise, pay attention to finding the corresponding numbers of each formula, and connect them accurately.

3. Question 4: Students do it independently. What do you think of the column formula? How many times one number is another has nothing to do with how many other numbers are in one number, which further enriches the understanding of the meaning of division operation.

Question 5: There are 40 children playing table tennis, all of whom take part in singles. How many groups can they be divided into? Are they all double? Pay attention to singles, every two, doubles every four.

5. Question 6: I will calculate the rectangle on the right to represent 120. How much does the colored part represent? ? Inspiration: What does the colored part have to do with this rectangle? Is this rectangle divided into several such rectangles?

? Fourth, the whole class reviews and summarizes exchanges.

1. Communication: Today we learned integer ten, integer hundred, and hundred divided by one digit. What new skills have you learned through this class?

5. Homework: Exercise 1 and 2 questions.

Blackboard design:

Oral calculation of whole ten (including hundred and ten) and whole hundred divided by one digit.

60÷3=20

① Three twenties are 60, so 60÷3=20.

(2) Six tens divided by three is two tens, which is 20.

③ 6÷3=2,60÷3=20

? 600÷3=200

(1) The sum of three 200 s is 600,600 ÷ 3 = 200.

Divide 600 by 3 to get 200, which is 200.

③ 6÷3=2,600÷3=200

120÷3=40

① The sum of three 40s is 120, 120÷3=40.

② 12 Divide ten by three to get four tens, which is 40.

③ 12÷3=4, 120÷3=40

Reflection after teaching: