Three teaching designs of "multiplication formula of 9" in the first volume of the second grade mathematics in the new curriculum standard primary school

Master the method of finding quotient by multiplication formula of 9.

Cultivate students' transfer ability, thinking ability and oral expression ability.

Cultivate students' ability to calculate correctly.

Teaching focus:

Guide students to master the method of finding business premises with 9 multiplication formula in self-inquiry.

Teaching difficulties:

Correctly use the multiplication formula of 9 to find the quotient.

Teaching preparation:

Multimedia courseware, etc.

Teaching process:

First, the introduction of new courses.

fill up a vacancy

() 9278 () 72

Four () thirty-six five () forty-five

() 9666 () 54

Answer first and tell me what you think.

24÷8 2 1÷7 40÷5 28÷4

Guide students to say the idea of seeking business.

Second, explore new knowledge.

1, teaching example 2

During the festival, children not only made flags but also made many heart-shaped balloons. Students, what mathematical information can be found by careful observation?

Default: There are 27 balloons, 9 in each row and 3 in * *.

(1) If we know that there are 27 balloons, how can we find out how many rows a * * * can hold?

(Formula 27÷9)

How to calculate? Which formula should I use?

(3927)

(2) If you know that there are 27 balloons and there are three rows, how can you find out how many balloons are in each row?

(Equation 27÷3, according to Equation 3927, the result can be calculated as 9)

Third, consolidate the practice.

1, complete the "do" 1-3 questions.

(1) Let all students participate and write the scores directly in the textbook.

(2) See who is right at the same time.

(3) As far as possible in the form of group competition, through the game to stimulate students' enthusiasm for participation, while strengthening students' mastery of knowledge.

2. Complete Exercise 8, Question 6.

Guide students to understand the meaning of the question. After students think independently, say the answers and then correct them collectively.

Complete Exercise 8, Question 7.

(1) Guide students to examine questions and get useful information from pictures. Whether the team wins or loses, there are eight people.

(2) After independent thinking, find out how many books each winning player can get.

(3) Divergent thinking, using the information collected in the pictures to ask mathematical questions, and the answer is no.

Fourth, class summary.

What have you gained from studying this course? What are the problems? Talk about your thoughts.

Blackboard design:

In the second class, use the multiplication formula of 9 to find the quotient.

27÷9=3

27÷3=9

How many books does the winning player get on average?

48÷8=6 (Ben)

extreme

First, the teaching objectives

Knowledge and skills

1. Let students experience the compilation process of multiplication formula of 9 and the source of multiplication formula of 9 through independent inquiry.

2. Understand the meaning of each multiplication formula, memorize the multiplication formula of 9 preliminarily, and make a simple calculation by using the multiplication formula.

(2) Process and method

By compiling the formula, I initially learned to draw inferences and explore new knowledge.

(3) Emotional attitudes and values

Feel the traditional culture of China and the team spirit in mathematics learning.

Second, the target analysis

The teaching content of this course is based on students' preliminary understanding of the meaning of multiplication and their study of the multiplication formula of 2-8. Students can completely summarize and memorize the multiplication formula of 9 through knowledge transfer, comparison and reasoning. At the same time, with the help of the number axis in teaching, the idea of one-to-one correspondence is preliminarily infiltrated, so that students can further understand the source of the multiplication formula.

Third, teaching focuses on difficulties.

Teaching emphasis: let students independently write the multiplication formula of 9 and use it to calculate.

Teaching difficulties: explore the laws in the multiplication formula of 9 and recite the formula.

Fourth, the preparation of teaching AIDS.

Courseware and homework paper

Teaching process of verbs (abbreviation of verb)

(A) Situation introduction, wonderful topics

1. Create a situation

(1) Show the picture in the courseware: Table tennis is China's national game, which is divided into singles and doubles, among which doubles need two people to cooperate. Please look at the situation map.

(2) Number of people: Do you know how many athletes are there in the picture? How did you ask for it? 4×3= 12 (name)

(3) Talking about ideas: We know that there are four people in a picture, and there are several four people here. Which multiplication formula do you use?

(4) Review formulas: What multiplication formulas have we learned? (2-8 multiplication formula)

Reveal the topic

Today, we will continue to learn the multiplication formula of 9 together. (blackboard writing topic)

The design intention is to create a table tennis doubles situation, which can not only review the application of multiplication formula, but also pave the way for the dragon boat competition situation. Let students use the existing knowledge and methods to explore the multiplication formula of 9 easily. At the same time, students can feel patriotism education and teamwork spirit in the situation.

(B) independent inquiry, building new knowledge

1. Actively explore

(1) Provide context: In China, there is a traditional sport-dragon boat race (the context map of the dragon boat race is shown one by one in the courseware).

(2) Collecting information: What information can be obtained by observing the situation map? There are 9 dragon boats, each with 9 people.

(3) Ask questions freely: Ask questions independently in groups and try to formulate. How many people are there on two dragon boats? How many people are there on three dragon boats? ...

(4) Communication report: Students may have two formulas: addition or multiplication. If there is a continuous addition formula, students can be guided to write a multiplication formula. (Write down each multiplication formula on the blackboard)

Make your own recipe

(1) Discuss the product of multiplication formula.

Show the number of axes and let the students fill in.

② Let the students talk about the meaning of multiplication. For example, 2×9 can represent the addition of several 9s.

(2) Self-made multiplication formula of 9.

(3) Write another multiplication formula according to the multiplication formula of 9.

3. Various forms, back formula.

(1) Find the pattern:

① What is the difference between two adjacent multiplication formulas?

② Look at the picture to find the rule: 10 square has 9 five-pointed stars, 1 space.

Student summary: 9 times a few equals dozens MINUS a few.

③ Finger memory method.

A. The courseware shows the finger exercises at the bottom of the textbook 8 1.

B. The teacher demonstrates the expression of multiplication formula of 9 with his fingers while introducing it.

C. students practice finger memory.

(Note: Leave enough time for students to explore the rules in the multiplication formula of 9 and encourage them to memorize the formula in their favorite way. )

(2) Password matching: Play password matching games between deskmates.

(3) Recite formula: recite formula at the same table.

The design intention is to explore the link of multiplication formula of 9, fully let students exchange and discuss, make their own formulas after solving problems, and reflect the students' dominant position. Because there are many multiplication formulas of 9, in memory, the teacher fully inspires students to find the law from different angles and guides students to remember faster and better through different forms.

(3) Apply what you have learned and consolidate the formula.

1. Apply base fertilizer

(1) Complete "Doing" on page 80 of the textbook. Consolidate students' application of formulas.

(2) calculation.

9×6 = 2×9= 5×9= ( )×7= 9×( )=72 ( )×( )=36

Improve exercise

(1) fill it in.

9+9+9=( )×( )=( )

9×8-9=( )×( )=( )

5×9+9=( )×( )=( )

(2) form a circle. Circle the formula with the answer of 18 in red and the formula with the answer of 45 in green.

9×2-9 9+9 4×9+9 9×7-9-9 9+9+9+9+9 9×3-9 6×9-9

Design Intention This lesson practices two levels of design. The basic application aims to further consolidate the multiplication formula of 9; The promotion exercise aims to make students use the multiplication formula of 9 flexibly through understanding the meaning of multiplication.

(4) Summarize the class and talk about the gains.

Tisso

Teaching objectives

1. Let students go through the compilation process of multiplication formula of 9, let students feel the interest of mathematics through the compilation process, and can use the formula to calculate accurately.

2. Cultivate students' preliminary knowledge transfer ability; Guide students to observe purposefully and make a preliminary summary.

3. Summarize various methods of memorizing formulas and infiltrate mathematics learning methods.

Emphasis and difficulty in teaching

1. Teaching emphasis: memorize the multiplication formula of 9 and apply it to calculation.

2. Teaching difficulties: explore the law of multiplication formula of 9.

teaching process

First, start listening to the song "One Master and Three Apprentices" to stimulate students' interest in learning.

Teacher: Students, do you like listening to music? Today, we listen to a song together. Please look and listen carefully. Find the numbers in the lyrics.

Teacher: Did you find the numbers in the lyrics?

Health: eighty-one, seventy-two, three, first class.

Teacher: You are so careful. The teacher told the students a secret: eighty-one and seventy-two have something to do with the multiplication formula of nine learned today. Today, let's learn the multiplication formula of 9!

Second, students * * * 9 multiplication formula (courseware demonstration)

1. Teach "Nine out of Nine".

Show pictures (* boat, 9 people rowing). Question: Look at this picture. 1 How many people are on board, that is 1?

The students observed that there were 9 people on board 1, that is 1 9.

List the multiplication formulas: 1× 9 = 9 or 9× 1 = 9.

Teacher: According to the multiplication formula, can you make up a formula?

Health: Nine out of nine.

2. Teach "298".

Show the pictures (two dragon boats) Q: How many people are there on the two boats? What does this mean?

Teacher: How should I add two 9s?

Students: 9+9 = 18, and the multiplication formula is: 2× 9 = 18 or 9× 2 = 18.

Teacher: Do you know what the formula is?

Health: 298.

3. Teach "3927,4936".

Question: What about three boats and four boats? How to form?

Health: When there are three 9,3× 9 = 27 or three boats, 9× 3 = 27. When there are four ships, there are four 9,4× 9 = 36 or 9× 4 = 36.

Teacher: The formula is ...

Health: three nine twenty-seven, four nine thirty-six.

4. Teach the corresponding formulas from 5 to 8.

Teacher: There are five nine companies on five ships. Do you know how many? How did you work it out?

Health 1: five nines are 9+9+9+9+9, two nines are 18, 18 and nine are 27, 27+9 = 36, 36+9 = 45.

Teacher: Is there any other way?

Student 2: I just learned 4936, that is, four nines add up to 36, plus 1 nine, that is, 36 plus 9 equals 45.

Teacher: Who do you think is the best of these two calculation methods and why?

Health: The second one is simple and convenient.

Observe three pictures of ships from six to eight in groups, and use the method of compiling formulas just now to explore and learn the corresponding formulas from six to eight independently.

5. Teach "998 1".

Teacher: By studying the first eight formulas, do you know how the formula "998 1" came from?

Health: Eight 9' s are 72, one more 9 is nine 9' s, and 72 plus one 9 is 8 1, so 998 1.

Teacher: 998 1, that is, nine 9+ companies. How much! It can be seen that it is really hard for Tang Priest and his disciples to experience the "81 difficulty"!

Third, remember the formula.

Teacher: Now give half a minute to see if you can remember all the formulas you have learned.

Question 1: Do you have any difficulty remembering the formula?

(The teacher recorded the formulas that the students had doubts about and checked them out with white chalk. )

Transition: See if the following study can help you solve it.

Question 2: Students who haven't encountered any problems, I think you must have some tips! Talk to your deskmate first.

(Teachers pay attention to the relevant contents of key laws and choose students to answer questions)

Question 3: What laws have you found? Tell us about them. (Teachers conduct guidance and inductive guidance according to students' random findings)

1. mnemonic method1-find the law.

Teachers guide students to discover the multiplication formula of 9.

Teacher: If you find the rules, you won't have any difficulty in remembering them. What is the law of multiplication formula of 9? Students don't have to look for these laws one by one. Students in different classes find different rules. Teachers should guide students to learn and master rules)

The multiplication formula of 9 * * has nine sentences: 199, 298, 3927, 4936, 594 15, 6954, 796 13, * 72, 998 1.

Their laws are as follows: the first number of each sentence is arranged in the order of 1 ~ 9; The product of every two adjacent sentences differs by 9.

Question: I remember the formula "796 13" and forgot the next sentence. What should I do?

The ten digits of the product are less than the first digit of the formula 1, and the sum of the ten digits and the single digits of the product is 9.

Teacher: 3× 9 = 28, am I right? Check it your way.

Compared with the previous formula, the digits of the latter formula are 1 and 1.

The formula of 9 seems to be inseparable from the numbers 1, 8, 2, 7, 3, 6, 4 and 5, so we can divide the formula into four categories: two, nine, three, eight, four, seven, five and six.

The formula of nine, the product of nine times several, take several as dozens, and then subtract a few.

Reason: Because 1 9 is 11minus1,two 9s should be like this, and two1minus 2 is 18, so three 9s should be 30 minus 3, is it 27, and those four 9s? (40 minus 4 equals 36) What about five 9s? (50 minus 5) Go on, so the product of 9 times several is dozens minus several. (Courseware demonstration)

9× 1= 10- 1 9×6=□-□

9×2=20-2 9×7=□-□

9×3=30-□ 9×8=□-□

9×4=□-□ 9×9=□-□

9×5=□-□

Teacher's summary: From different angles, we can find many rules about the multiplication formula of 9. Because of the time, I won't say them one by one. If you have anything else to say, you can tell me after class.

Teacher: Besides memorizing formulas by laws, what else can we memorize formulas by?

2. Memory method 2- Calculator on your body.

Hold out two hands, from left to right, in the order of 1 to 10, and calculate a number multiplied by 9. As long as you bend the corresponding finger, the hand index on the left of this finger is the number on the tenth place, and the hand index on the right is the number on the tenth place. For example, to calculate 3×9, bend the third finger from the left of the left hand, two fingers on the left represent 20, and seven fingers on the right represent 7, so the product of 3×9 is 27. Do not believe, you try.

3. Memory method 3-association method.

Today, when we watched The Journey to the West's cartoon, we knew that Tang Priest and his disciples had experienced the "81 difficulty" to obtain the true scriptures, which made us remember the formula of "eighty-one difficult". This is an associative memory method. At ordinary times, we have memorized some formulas in a similar way, for example, 36 plans are the best policy, regardless of the willy-nilly. Many things in life can help us remember formulas, so you should be a conscientious person.

Check the memory formula:

1. Teacher: There are so many ways to recite formulas. Those students who have just encountered difficulties should try again this time to see if your problem has been solved.

2. Teacher: Who wants to perform for you?

3. Sit at the same table and listen to each other.

Fourth, practice

1. Fill in the formula

49 () 5 () 45

() 9639 () 8 1

() 9723 () 27

() 986 () 54

2. Look at the formula and say two multiplication formulas.

Nine out of nine.

Seven nine six thirteen

Sanjiu phase 2

998 1

3. Look at the formula and say the formula

5×9=45

2×9= 18

4×9=36

7×9=63

Step 4 fill in the blanks

9×7= ( )×9=72 9×( )=27

7×( )=63 5×( )=45 9×8=

9×5= 9×6= 9×9=

Verb (abbreviation of verb) abstract

You learned the multiplication formula of 9 today. What have you gained?