Knowledge points, lesson plans and teaching reflections of "Addition and Subtraction within 100" for first-grade primary school mathematics

#一级# Introduction Mathematics is a basic science that is worth learning by everyone, especially children, who must learn mathematics and use it to construct their own thinking system. Learning mathematics is learning a system of thinking, and we should also pay attention to this in the daily teaching of children. The following is a collection of knowledge points, lesson plans and teaching reflection materials for first-grade primary school mathematics "Addition and Subtraction within 100". I hope it will help you.

Article 1 First-grade primary school mathematics "Addition and subtraction within 100" knowledge points 1. Add and subtract tens digits, and add and subtract ones digits.

1. Addition without carry 230=5067+2=6968+30=98

2. Subtraction without carry 80-50=3069-2=6798-30 =68

2. Carry addition (to make up to ten)

1. To make up to ten songs: one makes up nine, two makes up eight, three makes up seven, four makes up six, five and five make up Just make it ten. (Note: The two numbers used to round up ten are complements of each other)

2. Carry and add within 20: Method of rounding up ten: 8+72=15 Add 1 to the tens digit, subtract the complement of the ones digit (2+ 8=10, 2 is the complement of 8)

3. Carry within 100 plus 362+8=44 Refining method: connect the ones digit with an arc, add 1 to the tens digit, and subtract the complement of the ones digit . (The method is the same as within 20)

3. Retreat and subtract

1. Retreat and subtract within 20: Ten-breaking method: 161-9 = 7 ones plus complement

Teaching content of the second grade primary school mathematics "Addition and Subtraction within 100" lesson plan:

Example 2 on page 68 of the textbook, questions 5, 6, and 8 of Exercise 12.

Teaching objectives:

1. Master the calculation method of subtracting two-digit numbers from one-digit subtraction, and be able to correctly perform the calculation of subtraction.

2. Experience the process of exploring the calculation method of subtracting a two-digit number from a one-digit number by subtraction.

3. Feel the close connection between abdicated subtraction and real life, and appreciate the role of abdicated subtraction in life

Key points and difficulties:

1. Master two-digit numbers Calculation method for subtracting one-digit subtraction.

2. Encourage students to use a variety of methods to calculate.

Preparation of teaching aids and learning aids:

1. Teachers prepare courseware of scenario diagrams.

2. Students prepare 3 bundles of 6 small sticks.

Teaching process:

1. Pre-school preparation

Oral arithmetic. (Produced by computer. Students practice driving a train)

　11-3=　13-8=　17-9=　14-5=

　15-7=　12-3=　16-8 =　13-7=

Teacher talk: What knowledge did we learn in the last class? Let’s take a few questions and tell us what you think?

38-6= 87-3= 96-6=

Teacher’s talk: Change them to 38-9=, 87-8=, 96-8=, you will Does it count? Look closely and what do you find?

The students found that the numbers in the single digits of two-digit numbers are smaller than the subtrahends. If they subtract directly, is it enough to subtract? (Not enough to subtract) Then how to calculate these three questions? (Abdication), in this lesson we will study the abdication subtraction of two-digit numbers minus one-digit numbers.

Blackboard writing topic: Two-digit subtraction of one-digit subtraction

2. Exploring new knowledge

(1) Teaching example 2.

1. Guide students to list subtraction formulas from problem situations.

Courseware demonstration: Toy shelf screen in a toy store.

Teacher: In the last class, we have learned to solve problems such as "If you have 35 yuan and buy an elephant toy, how many yuan will you have left" based on the unit price of the toys on the shelf. What other useful information does the picture tell us? (An image of two toy cars is highlighted on the screen on the lower half of the shelf).

Student: The picture tells us that the prices of the two toy cars are 15 yuan and 36 yuan.

The courseware continues to demonstrate: two children have a conversation.

The child on the left is asking: "I only have 8 yuan. I want to buy a racing toy. How many yuan do I need to save?"

Teacher: What are the two children in the picture saying and thinking?

Student: The child on the left said: I have 8 yuan. I want to buy a toy car with a unit price of 36 yuan. How many yuan do I need to save? The child on the right is thinking about how to calculate how much money to save?

Teacher: Do you know how to calculate the formula? Why are they listed like this?

Students answer teacher’s blackboard writing

36-8=

2. Guide students to explore calculation methods

(1) Teacher: Calculation 36 What is the difference between -8 and the 35-2, 76-4 and other calculation formulas learned previously?

Student: The number in the ones digit of the minuend of calculations such as 35-2 and 76-4 is enough to subtract; while the number in the ones digit of the minuend of 36-8 is not enough.

Teacher: What should I do if the reduction is not enough? Let's swing it with a small stick first.

Make small sticks and discuss in groups the calculation method of 36-8.

(2) Guide students to talk about how to place sticks.

Teacher: Who can tell me about the process and method of placing sticks in your group?

Student: 6 is not enough to subtract 8. We first open a bundle and combine the original 6 sticks to get 16 sticks, and then subtract 8 sticks from 16 sticks.

Teacher: 8 sticks are left after subtracting 8 sticks from 16 sticks, plus the remaining 2 bundles (20 sticks), there are 28 sticks left. Write the number "28" after the equation.

(3) Guide students to summarize calculation methods.

Teacher: What did you discover from the process of placing the stick just now? Can anyone tell me the method of 36-8 based on the process of placing the stick?

Student: From the process of placing the sticks just now, I found that to calculate 36-8, you can divide 36 into 20 and 16, then subtract 8 from 16, and finally add 8 and 20 to get 36-8 difference.

(4) Guide students to explore other algorithms.

Teacher: Are there any other algorithms?

Student: You can also divide 36 into 26 and 10. Subtract 8 from 10 to get 2, and then add 2 to 26 to get 28.

Teacher summary: Just now we used several methods to calculate the abdication subtraction of two-digit numbers minus one-digit numbers. In future calculations, we can do it as easily as possible.

3. Consolidation exercises

1. Complete question 2 of "Do it" on page 68.

First, let the students calculate independently (students can be designated to calculate on the blackboard, and the rest can be practiced below), and then revise collectively.

When revising the answers, assign questions 1 to 2 to ask students to talk about their calculation process. The key point is to ask them to talk about: What should I do when the number in the ones place cannot be reduced enough?

2. Complete question 5 of Exercise 12.

First students calculate independently and then revise collectively. Combined with the process of correcting answers, let students talk about the calculation process and methods of 81-4 and 60-3, so that they can further experience the process of abdication and subtraction.

3. Complete question 8 of Exercise 12.

First let students clarify the calculation tasks, then calculate independently, and finally revise.

IV. Class Summary

Teacher: Please recall, students, what knowledge did we learn in this class?

Student: In this lesson we learned the subtraction method of subtracting a two-digit number from a one-digit number.

Teacher: How to calculate the subtraction of a two-digit number minus a one-digit number?

5. Homework

Part 3 Reflection on the teaching of first-grade primary school mathematics "Addition and Subtraction within 100" After finishing this class, a teacher said that the questions arranged in this section were a little bit It is difficult, many students cannot reach the level, and only a few students can figure it out. Some teachers also said that the highlight of this class is the design of the questions, which can trigger students' thinking, especially the design of four interesting questions, which is very helpful to students' subsequent calculation learning. The range of calculation results can be determined through estimation and excessive deviation can be reduced. brought errors. The purpose of my teaching design is:

1. According to the learning situation of our class, many students are only willing to accept mechanically, but are not willing to use their brains to think. They find slightly complex questions difficult and are unwilling to accept challenges in learning. , Of course, I can’t realize the joy brought by learning.

2. Make computing teaching less monotonous, mechanical, and repetitive.

3. I want to cultivate students’ observation and thinking abilities, train students’ ability to think in an orderly manner, comparative analysis and divergent thinking, and improve the level of independent student learning.

4. Through the guidance and demonstration of some outstanding students, let other students imitate.

It is true that students with learning difficulties have difficulties in learning in the classroom, but there are also surprises brought by students with strong expressive skills and flexible thinking. Through the teaching and collective evaluation of this class, I feel that diverging students' thinking, improving students' thinking ability, and listening habits are not something that can be achieved in an open class. Teachers need to carefully prepare lessons during the usual teaching process and be able to learn from the students in the class. Make an objective evaluation of the situation and develop a teaching design suitable for the students in this class.