Teaching objectives:
1, let the students divide the quotient of single digits by integers of ten, hundred and thousand, and divide the single digits by hundreds (or thousands).
2. Make students go through the process of dividing one digit by multiple digits, master the general writing, and use multiplication to check the division.
3. Let students estimate by division in specific situations, express the idea of estimation, and form the habit of estimation.
4. Make students feel the connection between mathematics and life, and be able to use what they have learned to solve simple problems in daily life.
Teaching emphasis: brush division.
The first class is divided by oral calculation (divided into two classes)
Teaching content: 13- 15 pages of drawings and examples 1.
Teaching objectives:
1. Understand and master the oral calculation method of one-digit division (the number on each digit of the dividend can be divisible by the dividend) in practical operation activities.
2. The simple divisor that can be calculated correctly and skillfully is the division of one digit.
3. Learn to listen and reflect in the process of communicating with others.
Teaching emphasis and difficulty: Let students understand and master the oral calculation method of tens of decimal digits through the practice of dividing sticks.
Teaching process:
I. Teaching examples 1
1. Show me 60 sticks. Observation: How many sticks are there? (Number of students, answer in parallel. )
If you want to divide these small pieces of wood into three parts equally, how are you going to divide them? How to form? How many are there in each serving? Students practice the operation and come to a conclusion. )
3. After breaking up, discuss your breaking up method in the group and dissolve.
4. If you don't divide sticks, how can you count as 60÷3?
Combined with the students' reports, the teacher wrote on the blackboard:
This makes 6÷3=2.
60÷3=20
6. Give it a try. (Students finish independently)
80÷4
60÷2
(1) Write the result by oral calculation. (2) talk about the oral calculation method.
Two. Teaching examples 1
the second question
1. Show the second question (2)
Can you work out the result orally?
Think independently first, and then exchange oral arithmetic methods in the group.
2. Combined with the students' reports, draw a picture to verify and compile a book: this is 6÷3=2 600÷3=200.
3. Give it a try.
360÷6 640÷8
Three. Teaching examples 1 question 3
1. Show me the third question. Can you work out the result orally?
Think independently first, and then exchange oral arithmetic methods in the group.
2. Combined with the students' reports, draw a picture to verify and compile a book: this is 24÷3=8 240÷3=80.
Fourth, consolidate practice.
1, orally calculate the following questions, and talk about the method of oral calculation.
40÷5 640÷8
2. Course summary
What did you learn in this class? What did you get?
Verb (abbreviation of verb) Homework: 17 Page 1.2
The second class is writing division.
Teaching content: 19 page example 1
Teaching objectives:
1. Understand and master the calculation order of dividing one digit by two digits and the positioning method of quotient through the process of dividing rods.
2. Learn the calculation method of one-digit division (every quotient of the dividend can be divisible by the dividend) and calculate it correctly.
3. Learn to think and solve problems in practice.
Teaching emphases and difficulties:
Based on the pen calculation of division in the table and the oral calculation of dividing one digit by two or three digits, the pen calculation division of one digit and two digits (the number on each digit of dividend can be divisible by dividend) is carried out. The difficulty is to help students understand where the dividend is and where to write the quotient.
Teaching process:
First, review the introduction.
Open the third page of the textbook and fill in the correct numbers in the boxes. 60÷3= 9÷3=
——————— 69÷3= 80÷2= 6÷2=
——————— 86÷2=
Second, new funding.
1. Give an example of 1. How many trees are planted in each class in grade three? Can you calculate continuously?
Tell me how you worked it out.
3. Can you calculate vertically? (Teachers' patrol guidance)
Ask the students on the blackboard to explain the reasons. According to his answer, students use sticks instead of books and get one point. See how he calculates and thinks, right?
5. Is there a problem? Students can't ask questions, but teachers can. )
6. Give it a try.
Third, consolidate the practice.
2 1 Page Question 2. The first two questions
Four. abstract
What did we learn today? What should I pay attention to when calculating?
The teaching plan of "Divider is the division of a single digit" in the second volume of the third grade mathematics (2) teaching objectives;
1. Through specific calculation, review and sort out the knowledge learned in this unit, so that students can form the knowledge structure of division with divisor as single digit and master the basic methods of oral calculation, estimation and written calculation.
2. According to the needs of practical problems, choose the calculation method flexibly.
3. Improve the flexibility, correctness and proficiency of calculation.
Teaching emphases and difficulties:
1. Teaching focus: build a knowledge network of division with divisor as one digit, and master the basic methods of oral calculation, estimation and written calculation.
2. Teaching difficulties: flexible selection of calculation methods to improve calculation accuracy.
First, create a situation and introduce review.
Teacher: Through the understanding before class, the teacher knows that the students in our class have strong computing ability, so today we are going to have a class related to computing. Please look at the big screen (presented courseware):
80÷2 238÷6
87÷3 832÷4
760÷4 720÷9
Observe these six formulas. What are their similarities?
Student: Dividers are all single digits.
Teacher: Yes, that's what we just learned in Unit 2. Divider is the division of a number (blackboard writing).
Second, review, organize and establish networks.
Please observe these six formulas carefully, which ones can be seen at a glance?
Health: 80÷2=40 720÷9=80.
Teacher: Do you agree? He also directly said the number, tell me how you got the result!
Health: I use my mouth to calculate.
Teacher: Give me a detailed introduction!
Health 1: 80 ÷ 2 = 40, because 24 gets 8, and then add a 0 after 4.
Teacher: Oh, he thought of the multiplication formula. Is that all right? (yes! )
What else can you think of
Birth at 2: 80 can be regarded as eight tens. Divide by 2 to get four tens, which is 40.
Teacher: Is it ok to think so? You go on to say what 720÷9 thinks!
Student: Think of 720 as 72 tens, and divide it by 9 to get 8 tens, which is 80.
Teacher: Well, does he speak well?
Health: OK.
Teacher: This is what we learned at the beginning of this unit-verbal calculation. (blackboard writing)
Let's look at the other four formulas. What is their quotient?
760÷4 87÷3
832÷4 238÷6
Health: 760÷4≈200
Teacher: Tell me what you think!
Health: It is estimated that 760 is 800,800 ÷ 4 = 200, so 760÷4≈200.
Teacher: Do you agree with him? That's great. Please sit down! Let's continue to watch 87÷3. What is the quotient? Health: The quotient is about 30.
Teacher: What do you think?
Health: It is estimated that 87 is 90,87 ÷ 3 ≈ 30.
Teacher: Is that what everyone thinks? The last two questions, just say it!
Health: 832 ÷ 4 ≈ 200 238 ≈ 6 ≈ 40
Teacher: Well, the students are really good! When finding their quotient, we use estimation. (Writing on the blackboard) Huh? Can you describe in your own words how you estimated it? Who will try to talk about it? The teacher asked someone not to raise his hand this time. Give it a try! Come on, the teacher thinks you can!
Student: The divisor is a constant. Think of the divisor as an integer close to it, and then calculate it by mouth.
Teacher: Look how well you speak! Why don't you raise your hand? Go for it!
He just said that the final solution is to use word calculation, but in fact the method used for estimation is word calculation, which means that estimation is actually part of word calculation.
Teacher: Just now we just estimated the approximate number of quotient. In order to get accurate results, we still need column vertical calculation. (Writing on the blackboard: a pen calculator) The pen calculator is definitely the "hard bone" of this unit, because it is easy to make calculation mistakes. In order to reduce errors, you can judge the number of digits of quotient first, and then do a written calculation. Remember how to judge the number of digits of quotient?
Student: Yes.
Teacher: Let me think. How many is the first quotient?
Student: Double digits.
Teacher: How many people is the second quotient? Student: Three digits.
Teacher: The third one? Student: Double digits.
Teacher: The fourth one? Student: Three digits.
Teacher: Alas, pay attention to the following three formulas, all of which are one digit divided by three digits. Why are some quotients with two digits and others with three digits?
Health: It depends on whether the highest digit of dividend is quotient 1.
Teacher: What do the students think?
Health: Well, that's right!
Teacher: Let's look at this formula again. We don't know the number of these hundreds, so how many chambers of commerce are there?
Health: It may be two digits or three digits.
Teacher: Look! (ppt)
Health: If the quotient is two digits, you can put 1, 2,3,4,5 in □.
If the quotient is three digits, you can put 6, 7, 8 and 9 in □.
Teacher: Do you think so?
Health: Yes.
Teacher: It seems that everyone has a thorough understanding of this problem. Let's work out their exact results quickly. Let's start!
Ask two students to act out two formulas: 760÷4 832÷4.
afterwards ...
Teacher: Have all the students finished their calculations?
Health: It's over!
Teacher: Oh? Is it over? So is the result calculated by everyone correct?
Health: Oh! You can check it!
Teacher: Choose 1 from these four formulas to check whether your calculation result is correct!
Have you finished the inspection? Who can tell me which formula you chose and how to check it?
Health: I chose the first one and used 29×3=87.
Teacher: That is to say, multiply the quotient and divide it to see if the result is equal to the dividend. Do you agree?
Health: I agree!
Teacher: Alas? What if there is a remainder?
Health: If there is a remainder, you have to multiply the quotient by the remainder to see if the result is equal to the dividend.
Teacher: Is that how you check? (yes! )
Who can tell me the answers to these four questions?
Health: 760÷4= 190
Teacher: Is that right?
All students: Yes!
Teacher: Go on!
Student: 87÷3=29 All students: Yes!
Student: 832÷4= 208 All students: Yes!
Life value: 238 ÷ 6 = 39...4 All students: Yes!
Teacher: If you have the same answer, please raise your hand! Students' computing ability is really strong!
Let's look at the blackboard writing of these two students again. Come on, please welcome two students to the stage!
Let me explain to you how you calculate step by step.
Health: 760÷4, divided from the highest point, quotient 1, one-four gets four, remainder 3, drop 6, quotient 9 36 ÷ 4 ÷ 5 ÷ 5 ÷ 6 ÷ 6 ÷ 5 ÷ 5.
Teacher: Does she (he) speak well? It's wonderful!
Let's move on to the next question. How did you work it out step by step?
Health: 832÷4, also from the highest punishment. Quotient 2, 24 gets 8, and there is no remainder. Remove the third from the tenth place. 3 divided by 4 is not enough quotient 1, and then 4 in the unit is removed. Divide 32 by 4 to get 8,4832.
Teacher: Is he right? Not only is the thinking clear, but the writing style is also very neat and standardized! But the teacher still has some questions? The quotient of these two questions is zero. How did these two zeros come from? Can you explain it? )
Health 1: 760 ÷ 4, divide by several digits of 0 to get 0, so you don't need to divide it, just divide it directly!
Teacher: Is that right? (yes! Let's look at the next question, how did you get the 0 in the middle of the quotient?
Health 2: 832 ÷ 4, the tenth 3 divided by 4 is not enough quotient 1, only quotient 0.
Teacher: Are you satisfied with their answers? (satisfied! )
The teacher is also very satisfied, thank you two little teachers, please come back!
Teacher: OK, class, what do you think we should pay attention to in the writing process just now? (Pause) Tell your friends quickly!
When the students are discussing, the teacher writes on the blackboard: one digit divided by two digits, one digit divided by three digits.
Teacher: Who will say something?
Several students tried to say methods or precautions: from the highest place, one is not enough to see the first two, except quotient, the remainder is less than divisor. ...
(Refine the four-word method in time: look, do, calculate and check)
Teacher: these are the calculation methods and skills of division with divisor as single digit. You will learn how to divide divisors into two digits and three digits in the future. Their calculation method is the same!
Teacher: First of all, we have combed and reviewed all the knowledge of Unit 2, which also involves the calculation of division and the calculation of quotient with 0 in the middle or at the end. The teacher believes that everyone's computing ability has improved again. Let's have a try, shall we? (all right! )
Third, pay attention to review, strengthen and improve.
Teacher: Come on! Just say it! Answer together! (Courseware presented one by one)
40÷4= 808÷9≈
900÷3= 14 1÷2≈
300÷5= 7 18÷8≈
2700÷9= 449÷5≈
Teacher: Well, the students are really amazing! Let's compete to win the red flag! (ppt presentation exercise)
Can you understand its meaning? Oh, don't worry, let's divide the work first! Students are divided into two parts. The students here are from the right and the students here are from the left. Let's see which side reaches the top first to win the red flag! You got it? Let's go (Raise your hand to signal the teacher when you are finished) (Show courseware)
(later)
Teacher: Here 1 the classmate won, and here's a classmate finished!
Are you all finished? (finished! )
It's not enough to do it quickly, you have to make sure you can do it right! Hurry up and check the answer with your friends!
(Later) Is that all right?
Health: No problem.
Teacher: Which student won? In fact, the teacher felt that the students on both sides were evenly matched and performed well. You are all winners!
Fourth, expand and extend.
The teacher is going to buy some notebooks, which happens to be a special sale in the supermarket. Do you know what "buy 8 get free 1" means?
Student: Buy 8 notebooks and send them to 1 set!
Teacher: Is that right? How many notebooks can 5 yuan and 80 yuan buy at most?
Students think ...
Teacher: Some students think they can buy 16 copies, but alas, it seems that they can buy 18 copies! I'm not sure. It seems that this problem deserves further study. Can we leave it until after class?
Teacher: All right, class, through the study of this class, the teacher hopes that everyone can gain something.
That's all for this class. Goodbye, class!
Grade Three (3) New Knowledge Point Mathematics Volume II "Divider is the division of single digits" teaching plan
1, oral English teacher.
(1) oral calculation.
(2) estimation.
2, the pen master.
(1) basic pen division.
(2) Calculation of division.
Emphasis and difficulty: division of 0.
Teaching requirements:
1, let the students divide the quotient of single digits by integers of ten, hundred and thousand, and divide the single digits by hundreds (or thousands).
2. Make students go through the process of dividing one digit by multiple digits, master the general writing, and use multiplication to check the division.
3. Let students estimate by division in specific situations, express the idea of estimation, and form the habit of estimation.
4. Make students feel the connection between mathematics and life, and be able to use what they have learned to solve simple problems in daily life.
Teaching suggestions:
1, strengthen students' independent inquiry activities and attach importance to the exploration of arithmetic and calculation rules.
In order to prevent students from mechanically memorizing the process of oral calculation and applying calculation rules without knowing arithmetic, this textbook does not indicate the general idea of oral calculation, nor does it show the division rules of divisor by written calculation. But fully mobilize the existing computing knowledge and experience, and actively explore computing theories and algorithms.
(1) Activate students' existing oral calculation experience and make them migrate to oral calculation division with divisor of one digit.
Students' existing oral calculation experience related to the division of divisor into single digits includes: division in table and oral calculation of multiplying single digits by whole ten or whole hundred. These oral calculation experiences are the basis to help students solve the oral calculation division with divisor of single digits. Therefore, active measures should be taken in teaching to activate students' stored related oral calculation experience, arouse students' memory of existing knowledge, and use it flexibly under the new situation that divisor is single digit.
(2) Guide students to explore the arithmetic and calculation rules of pen division and learn the orderly thinking method of "what to do first-what to do next-what to do last". In teaching, we should make full use of students' oral calculation experience and combine some intuitive operation activities to make students develop orderly thinking and operation habits, so as to independently sum up the calculation rules of written division.
(3) Guide students to express their thinking process in concise language.
The process of guiding students to express oral calculation and written calculation in mathematical language is actually the process of guiding students to summarize and sort out operation procedures and laws, and it is the refinement and sublimation of calculation activities. In this process, teachers should create conditions and give students a relaxed speaking environment. First of all, let the students talk to themselves and whisper their thinking process when thinking about each example. Secondly, let the students talk about their own thinking process in the group (or at the same table). Finally, provide examples of speeches. Let the students who speak well communicate in the class, or the teacher can summarize the different problem-solving strategies of the students in the class according to the expressions of several students. Through hierarchical process and reasoning, students can independently summarize the basic methods of derivation calculation or pen calculation division. At the same time, learn to express your thinking process in concise language.
2. Broaden the situational horizon of the theme map.
In order to let students learn how to divide into single digits in problem-solving situations, the textbook has designed colorful life scenes that students are familiar with, from which some problems need to be solved by division. However, these materials can't meet the requirements of teachers and students. Therefore, in actual teaching, teachers should adjust measures to local conditions, and link division learning with people's living environment, healthy growth, transportation, sports, entertainment, diet and popular science knowledge according to students' needs, so that boring division calculation can be rooted in all human activities and students' learning interest and exploration can be improved.
3. Put the estimation in the same important position as oral calculation and written calculation.
"Being able to estimate according to the specific situation and explain the process of estimation" is the learning goal of the Mathematics Curriculum Standard for students. To achieve this goal, teachers' teaching behavior should have the following changes:
(1) It is of great significance for the cultivation of students' sense of numbers to fully understand the extensive role of estimation in daily life and work.
(2) Combining the teaching of estimation, oral calculation and written calculation. In teaching, we should pay attention to guiding students to combine estimation algorithms in specific problem situations, so that students can truly feel the role of different calculation methods and the application value of estimation.
(3) appropriately supplement some estimation contents closely related to students' life, strengthen the application of estimation, and cultivate students' estimation consciousness.
4. Strengthen the connection of multiplication and division to improve students' simple reasoning ability.
There is a close relationship between multiplication and division. In teaching, we should pay attention to guiding students to start with the relationship between multiplication and division and transfer the thinking method of multiplication to division. For example, teaching 60÷3= () can guide students to think 3×( )=60. For another example, when checking teaching division, we can deduce the test method of checking division by multiplication according to the reciprocal relationship of multiplication and division. In this way, by starting from the opposite cube of contradiction, students are guided to reveal the relationship between knowledge, so that students can not only master the division calculation of divisor into single digits, but also cultivate their dialectical materialism view.