Knowledge points, lesson plans and teaching reflections on "Division" in third grade primary school mathematics

#三级# Introduction Division is one of the four arithmetic operations. Given the product of two factors and one of the non-zero factors, the operation of finding the other factor is called division. The division of two numbers is also called the ratio of the two numbers. The following is a compilation of knowledge points, lesson plans and teaching reflection related materials for third-grade primary school mathematics "Division". I hope it will help you.

Article 1 Knowledge Points of "Division" in Mathematics for the Third Grade of Primary School (1) Oral Division

1. Oral calculation method of dividing whole thousand, whole hundred and whole tens by one digit.

(1) Calculate using table division: first divide the number before the dividend 0 by a single digit. After calculating the result, look at how many 0s are at the end of the dividend, and add after the calculated result. Several 0's.

(2) Use multiplication to calculate division: see how much a single number multiplied by is equal to the dividend, and the multiplied number is the quotient required.

2. Estimation method of dividing three-digit numbers by one-digit numbers.

(1) Keep the divisor unchanged, treat the three-digit number as a number of hundreds, tens or hundreds, and then use the basic method of oral division to calculate.

(2) Think of formulas to estimate: Think of the number of times a single digit is closest to or equal to the digit or first two digits of the dividend, then hundreds or tens is the quotient to be estimated.

(2) Written division methods

1. Firmly master the written calculation methods, steps and formats of dividing two-digit numbers by one-digit numbers and dividing three-digit numbers by one-digit numbers, especially How to write arithmetic formulas with 0 in the middle and at the end of the quotient.

(The calculation rule is that the divisor is a single digit. Starting from the high digit of the dividend, divide the previous digit of the dividend first. If it is not enough, divide the first two digits of the dividend. Whichever digit of the dividend is divided, the quotient is written above the digit of the dividend. If the digit of the dividend is less than 1, the remainder of each division must be smaller than the divisor.) < /p>

2. Can determine the number of quotients.

Compare the size of the divisor and the dividend digit. If the number in the dividend digit is smaller than the divisor, then the quotient must be one less than the dividend; if the number in the dividend digit is greater than or equal to the divisor, then the quotient and the dividend are digits are equal.

3. Calculation method for division:

(1) Division without remainder: quotient × divisor = dividend;

(2) Division with remainder: Quotient × divisor + remainder = dividend;

4. Some regulations about 0:

(1) 0 cannot be used as a divisor.

(2) The division quotient of two identical numbers is 1. (Since it can be divided, this number is not 0)

(3) 0 divided by any number other than 0 is 0; 0 multiplied by any number is 0.

5. Estimation of multiplication and division: 4 rounding to 5 method.

For example, multiplication estimation: 81×68≈5600, that is, 81 is estimated as 80, 68 is estimated as 70, and 80 is multiplied by 70 to get 5600.

Estimation by division: 493÷8≈60, which means estimating 493 as 480 (480 is a multiple of 8 and the closest to 492), and then calculate 480÷8 to get 60.

Teaching objectives of the Lesson Plan for Mathematics "Division" for the third grade of primary school:

1. In the process of solving practical problems, realize that the result of dividing 0 by any number other than 0 is equal to 0 .

2. Experience the process of exploring the calculation method of division with 0 in the middle and at the end of the quotient, and be able to calculate it correctly.

3. In the process of solving practical problems, feel the connection between mathematics and daily life, enhance the awareness of independent exploration, and improve the ability of cooperation and communication.

Teaching process:

1. Teaching example 1

1. Create a situation and ask questions

Show the situation diagram and ask: From What do you know about the picture? How many mushrooms can each rabbit pick on average? How to calculate it?

How many peaches can each monkey pick on average? How can we list them?

2. Combining old knowledge to solve problems

Three little monkeys picked peaches, but there were no peaches on the tree. How many peaches do you think each little monkey could pick? ?

If you can’t pick one, what is 03 equal to?

What will happen if 4 little monkeys pick peaches? What about 5? What about 9? How to list the calculation formula? The result?

Question: Looking carefully at these calculations, what did you find?

Guide: 0 divided by any number that is not 0 is 0.

2. Consolidation exercises

Think, do and do 1

Students will be named to answer after completing independently.

Summary: 0 divided or multiplied by any number other than 0 is equal to 0.

3. Teaching Example 2

1. Create situations and ask questions.

Show a sample picture and ask: What do you know from the picture?

Question: How to calculate the average number of kilograms of eggs produced per day in the first three days?

2. Explore independently and solve problems.

Conversation: What is 3063? Estimate first, then do the math.

Understand students’ methods and selectively ask students to write their methods on the blackboard.

Question: What is the approximate quotient of 3063? How did you estimate it?

Focus on learning pen calculation methods and writing formats.

Analysis guidance: Why is 0 written in the tens place of the quotient (because 0 divided by 3 is 0)? Can this 0 not be written? Why? Let students make it clear that 0 has a placeholder role.

Explain writing format.

Question: What do you think about comparing the calculated results with the estimated results? What if the 0 in the middle of the quotient is missing?

IV. Complete the test

1. Show the question and ask students to tell what the quotient is.

2. Students complete the work independently in the book and perform on the board by name.

3. Let the students in the boardroom talk about the calculation process.

4. If the vertical expression written by the students is not simple enough, guided analysis can be conducted: Can the vertical calculation in the last step be omitted? If omitted, should I write 0 in the ones position of the quotient? Where should I write 0 to indicate completion of division?

5. Summary: If the ones digit of the dividend is 0 and the division to the tens digit of the dividend is complete, you can directly write 0 in the ones digit of the quotient.

5. Summary of the whole lesson

Comparing the example questions and the trial questions, what do you think are the differences? What are the similarities? What conclusion can you draw?

Summary: If there is a 0 in the middle or at the end of the dividend, and the division is completed by the digit before 0, just align the 0 in the dividend directly and write 0 in the quotient.

6. Consolidation and improvement

1. Think about it, do it 2

Show the questions and let the students tell what the quotient of each question is.

Then complete it independently and perform it by name.

Choose two questions and let students talk about the calculation process.

2. Think and do 3

Independently find out the cause of the error in the 3 questions, correct them, and then answer them by name.

7. Homework

Think and do 4

Part 3 Reflection on the Teaching of Mathematics "Division" in the Third Grade of Primary Schools The initial understanding of division is the beginning of students' learning of division . The teaching suggestions mentioned: Let students set up learning tools, watch courseware to demonstrate the process of scoring, and other activities to fully understand the relationship between average scores and division, and truly implement the key points and breakthrough difficulties.

The teaching tasks of this part of the content are very heavy, and they are related to multiplication and average scores. Therefore, I give the power of learning to students in teaching. When designing lesson plans, I determine the focus of teaching to make students know the meaning of division through actual division of things. Use the average score to guide the operation. Let the students use 12 small items instead of bamboo shoots and divide them into 4 equal parts. Find the number of each part.

When I asked them to use the average score to introduce their works, they all raised their hands high, vying to come up and express themselves. The classroom has become a garden full of experience and fun. Maybe this kind of classroom lacks a lot of classroom routines of sitting upright, but I have been pleasantly surprised by the children's free thinking. After solving the average score, the teacher pointed out that dividing the 12 small items into 4 equal parts, each of which contains 3 pieces, can be represented by division, so he abstracted the division formula. Teach the pronunciation and meaning of division formulas based on division formulas.

String the math problems around the red panda like candied haws, please make a guest appearance. During the entire learning process, I arranged the following activities one day, including pandas dividing bamboo shoots, biscuits, apples, and watermelons. These activities all take place during the red panda treat, giving students a sense of wholeness and intimacy. In addition, stringing the situations together makes it easier for students to learn systematically, making students' thinking more active as the storyline develops. It is easier to understand mathematical problems and problem-solving abilities, enhance students' internal drive to learn, and stimulate a strong interest in learning mathematics.

Disadvantages:

1. The teacher did not fully understand the teaching material. Writing division equations is also a focus of this lesson, but the teacher only paid attention to oral presentation and did not allow students to practice. The formulas are listed above.

2. The meaning of the division equation can be passed over briefly. Instead, the teacher repeats it many times and asks students to follow it, which wastes a lot of time and results in a small classroom capacity.

3. The teacher’s language is not refined enough.

4. Teaching in lower grades should pay attention to the cultivation of students' learning habits. Teachers should require students to put away their learning tools in time when they are finished.