Find the number that is more or less than a number

Teaching content: 33 pages of example questions and 34 pages of Thinking and Doing in the second volume of Jiangsu Education Edition for Grade 2 students.

Teaching objectives:

1. Knowledge and skills: enable students to connect the meaning of addition and subtraction operations with their own life experience, explore and understand "finding more (less) than a number" Quantitative relationships in simple practical problems such as "What is the number of a few?" and be able to use addition and subtraction operations to correctly answer them.

2. Process and method: In the process of solving problems, students can further deepen their understanding of the meaning of addition and subtraction operations, cultivate the ability to think based on the basis, and initially learn to reflect on the rationality of answers based on the meaning of the question. nature, and constantly accumulate experience in solving simple practical problems.

3. Emotional attitudes and values: enable students to further feel the close connection between mathematics and real life, experience the fun of cooperation and communication with classmates, and enhance their confidence in learning mathematics well.

Teaching focus: Explore and understand the quantitative relationship in simple practical problems such as "finding how many more (less) numbers are there than a number", and be able to use addition and subtraction operations to answer them correctly.

Teaching difficulties: explore and understand the quantitative relationship in the simple practical problem of "finding how many more (less) numbers than a number"

Teaching preparation: self-made courseware, magnetism There are 33 flower pieces, and some flower pieces for students.

Teaching process:

1. Review old knowledge and pave the way for new lessons.

1. Do children like playing games? Today let's play a game of catching flower pieces. The teacher has a bunch of flower pieces here. You can only grab a handful to see who can catch more. (Invite two students to catch them)

2. Teacher: Guess who caught the most? (Students can guess whatever they want)

Teacher: Who has more, and how many more? Just arrange the flower pieces in a row and you will know.

Teacher: First, arrange the girls’ flowers in a row (girls). Board post: OO…OOO

Teacher: Pay attention to how the teacher arranges the boys’ flowers… ? Board post: OO...O

Student: One against the other.

Teacher: What’s the use of putting them one against the other? (You can tell who has more and who has less at a glance) Yes, in this way we can say that girls catch more than boys, how many? On the other hand, there are fewer boys than girls. How many less?

3. Problem reveal: In this lesson, we will learn together the simple practical problem of finding the number that is more (less) than a number. (Board post topic)

4. Yesterday, Sunday, Xiaoying also played the flower-catching game with her good friends Xiaohua and Xiaoping! Let’s take a look at their results!

2. Explore new knowledge and teach examples.

1. Display the sample question scenario picture (courseware display: click to display the information of three people arranging flowers).

2. Guide students to talk about what information you know? Nominate students to answer and write on the blackboard:

Xiaoying: There are 11 flower pieces

Xiaohua: There are 3 more than Xiaoying

Xiaoping: Than Xiaoping Ying Shao puts 3 pieces

3. After reading this information, can you ask some mathematical questions?

(1) Guide students to ask: ①How many should Xiaohua place? ②How many Xiaoping should be placed?

(2) Let’s look at the first question first:

①According to Xiaohua’s words, we can use flower pieces to arrange them in a row, and then we can know how many flowers Xiaohua wants to place. Alright, do you want to give it a try? Think about how to place it so that you can clearly see that Xiaohua has 3 more places than Xiaoying? Tip: Place them one behind the other under the first row. (Open the small box of learning tools)

②Students open the small box of learning tools and operate them by hand.

③Tell me how you put it? The students answer and the teacher acts out the answer.

--" Question: When placing Xiaohua, why do we have to place the 11th one first?

--"Thinking: When the second row is the same as the first row, why do we need 3 more?

--》Feedback: How many flower pieces did we place? How to calculate by column? Writing on the blackboard: 11+3 = 14 (pieces)

--》Discussion: Is the calculated number the same as the displayed result? Why use 11 plus 3? What does 11 represent? What does 3 mean? Is the number more than 11? (Guide students to substitute the calculated numbers into the conditions to reflect on the rationality of the answers.)

4. Transition: Name the student: Now who can tell how many flower pieces Xiaohua has placed?

(1) How many should Xiaoping place? Can you first place it yourself and then calculate how many pieces Xiao Ping placed?

(2) Students do hands-on operations and calculations and fill in P33 in the book.

(3) Discussion: How many are in the first row? How to arrange the second row so that it can be clearly seen that Xiaoping has 3 fewer rows than Xiaoying? Why use subtraction? What does 11 mean? What does 3 mean? Are the calculation results the same as the flower pieces laid out? Answer by name.

5. Teacher’s summary: We found the number of flower pieces that Xiaohua and Xiaoping wanted to place by placing them first and then calculating. After calculating the answer, we also needed to use the known Condition, see if this result meets the condition of "more (less) than...".

3. Provide guidance to complete “think, do, and do”.

1. Do the first question of “Think about it, do it”.

(1) Students look at the picture and explain what the known conditions are and what the required questions are. And talk about it completely, (2) students’ solution to the equation. (If some students have difficulties, they can use learning tools to lay out the formulas first and then list the formulas.)

(3) Feedback: Talk about the formulas and answer sentences.

(4) Guide reflection: Will the number be less than 32 squares? Why?

2. Think, do, and do 2

(1) Students answer the questions independently, naming the formulas and answers.

(2) Guide reflection: Will the number be more than 36 pots?

3. Think and do 3.

(1) Students answer the questions independently, naming the formulas and answers.

(2) Transition: The students have learned so well, the teacher can’t help but applaud you, please listen:

4. Clapping game

Teacher After 3 shots, the teacher said: Can you take 2 more shots than me? (Named shot)

The teacher took 5 shots, and the teacher said: Can you take 2 less shots than me? (Named shot)

The teacher took 4 shots, and the teacher said: Can you take 2 more shots than me? (shoot together)

4. Class extension

Teacher: I didn’t expect that mathematical knowledge is also used in a relaxing game! The teacher has some interesting questions here. Do you want to challenge them? .

1. According to the conditions shown in the picture: □□□□□□□□□

○○○……

(1) Teacher: O here There is a... at the back, do you know what it means? Let me give you an example first! Teacher demonstration: ○ is 2 less than □, how many ○ are there? (Nominate answers: 9-2=7 (number)

(2) Anyone can tell a condition and let everyone calculate it.

2. Is it interesting? Xiao Ying, Xiaohua and Xiaoping saw that everyone was studying well, and wanted to test everyone.

(Courseware provided: Conditions: Xiaoying placed 15 flower pieces, Xiaohua placed better than Xiaoying Few, Xiaoping has more than Xiaoying.

(Requirement: Arrange it in your mind first, and then discuss:)

(1) Who has more flower pieces, Xiaohua or Xiaoping?

(2) Among the three of them, who does it the most and who does it the least?

(3) How many may Xiaohua have placed? What do you think?

(4) How many of them might Xiaoping have placed? What do you think?

3. Do you still want to challenge? Think about it, do you know how many black rabbits there are?

(1) There are 30 white rabbits, and there are 10 more black rabbits than gray rabbits. How many black rabbits are there?

(2) There are 30 white rabbits. There are 20 fewer white rabbits than black rabbits. How many black rabbits are there?

--》Students think independently, tell me what you think?

--》Summary: Through these two questions, what do you have to tell everyone? (When we are calculating the simple practical problem of finding how many numbers are more (less) than a number, we must read the question carefully. We cannot add when we see more or subtract when we see less.)

5. Class Summary

What did you gain from studying this class? Use the skills you learned today to solve some problems in life. I believe you will become smarter and smarter!

6. Classwork:

Complete question 4 of "Think, Do, Do" in your math homework book.

7. Blackboard writing design: