Reflections on the teaching of decimal addition and subtraction 1 I thought this was an easy course to explain, and children should be able to use integer calculation method step by step according to the steps I designed.
When I wrote the formula of 0.8+0.6 on the blackboard, the children told me that the answer was 0. 14. I was curious and asked her why she thought so. She said that integers add up to integers, and decimals add up to "0+0 = 0,8+6 =14, so it is 0. 14." That sounds reasonable. I am anxious to explain that it will be displayed vertically immediately and explain the alignment of numbers. Pay attention to decimal addition and subtraction immediately: integer and integer part are aligned, decimal point and decimal point are aligned, and decimal part and decimal part are aligned. So 0.8+0.6= 1.4 When I published this answer and wrote it on the blackboard, Tan Sitian's little hand held high. I knew she had something to say, so I told her to stand up and say it. She immediately said that 0.8+0.6 should not be equal to 1.4, but should be equal to 0. 14. The reason why the decimal part adds up to ten should be written in the decimal part. I was deeply impressed by the child's reasoning. I was really caught off guard, because I didn't presuppose such a question. I said half jokingly, "I usually test you." Today, Mr. Liu was tested by you. Let's answer together. " So I used integer addition to explain it, telling them that when the number of digits and ten are aligned, they all advance one place, and then they will not write. She seems confused about doing it.
After class, I reviewed my answers in class, feeling that I didn't really convince my children, and I didn't let them understand why the addition of decimal parts can't be written as decimal parts, but should be written as integers after ten. It can be seen that you haven't fully understood the textbook when preparing lessons. Don't think that simple content can be explained and absorbed by students. I am glad that their curiosity can arouse their interest in mathematics, and they are also willing to explore and analyze it. I need to protect their curiosity and interest and adjust my teaching mode.
Reflections on decimal addition and subtraction teaching II. Is decimal addition and subtraction a standard experimental textbook for compulsory education courses published by People's Education Press? The content of the first lesson of unit 6 in the second volume of mathematics in grade four. Before this, students systematically studied integer addition and subtraction, and more firmly mastered the calculation method of integer addition and subtraction. In the third grade, I also calculated the addition and subtraction of a decimal place. Although the addition and subtraction of decimals are calculated, no calculation rules are formed. At the same time, the fourth unit of this book systematically studies the meaning and nature of decimals. Therefore, students have a good foundation to learn decimal addition and subtraction. How to use knowledge transfer to let children learn independently and understand the arithmetic of decimal addition and subtraction is a problem that I have been thinking about when preparing lessons.
In order to better stimulate students' interest in learning, I creatively use teaching materials in teaching. After repeatedly studying the textbook, I boldly abandoned the original theme map and examples of the textbook and created a shopping situation. The reason for this is that the diving performance of the 2004 Athens Olympic Games, the material provided by the textbook, has been a long time for students, and they are not interested at all, and they are far from familiar with shopping. The difficulty of decimal addition and subtraction is the calculation of decimal addition and subtraction with different decimal places, which cannot be reflected if the situation in the textbook is selected. Based on the above reasons, I chose Commodity Price as the textbook of this course.
In order to better guide students to use the old knowledge of integer addition and subtraction to migrate to the new knowledge of decimal addition and subtraction, I emphasized the following two points in teaching:
First, stimulate students' desire to learn and find the connection between old and new knowledge.
At the beginning of the class, let the students talk about where they will meet decimals, feel the role of decimals in life, and know that learning decimal addition and subtraction is the need of daily life and further study and research, thus leading to the topic. Let the students recall what they have learned before. What should they pay attention to when calculating integer addition and subtraction? And encourage students to ask questions boldly according to the topic, and put forward the problems they want to solve, which is helpful to cultivate children's problem awareness and questioning ability. In class, the children raised many valuable questions, such as: how to calculate the addition and subtraction of decimals? Integer addition and subtraction calculation should be full ten into one, is decimal addition and subtraction valid? In fact, students pay attention to the connection between new knowledge and old knowledge they have learned before, which points out the direction for classroom inquiry learning and stimulates students' desire and interest in learning inquiry.
Second, the combination of question guidance, teacher support and release can guide students to understand arithmetic and algorithms.
Because students have the basis of integer addition and subtraction, they make full use of this knowledge and experience in teaching, create shopping situations, show three kinds of goods and prices, and let students ask questions and solve problems according to information. Among the questions raised by the students, the teacher chooses one of them to show (two decimal places plus two decimal places) and asks the students to list the formulas independently and try to calculate. Because the third-grade students have learned to add and subtract a decimal, they unconsciously align the decimal point. They don't involve arithmetic and algorithms here, just through the question "why do you use addition?" Let the students know that decimal addition and integer addition have the same meaning.
I put arithmetic and arithmetic in "Help the teacher figure out how much it costs to buy a box of watercolor pens and a book?" (Two decimal places plus one decimal place) Is 20 yuan rich enough? How much is left? (Integer minus two decimal places). Let students try to calculate and experience the learning process first. In the collective communication, I designed the following questions:
1. In the past, when calculating addition and subtraction problems, the last one was aligned. Why not align with the last one now?
2. What can decimal point alignment guarantee?
3. How to quickly align the same numbers when calculating decimal addition and subtraction?
4. What is the difference between decimal addition and subtraction and integer addition and subtraction when aligning the same number of digits?
5. Why do we have to align the same numbers? Talk about your understanding with specific figures.
6,20 has no decimal point, how to calculate it? According to what?
Through the guidance of these questions, guide students to understand the operation of decimal addition and subtraction. In this series of learning activities, the teacher did not give any hints to the students, reminding them to solve problems according to their existing experience, trying to write decimal addition and subtraction vertically, raising their initial understanding to a new height through teacher-student exchange activities, summarizing the general methods of decimal addition and subtraction, and further understanding the principle of decimal point alignment when columns are vertically arranged.
I thought I had thoroughly studied the textbook and made a lot of preparations before class, but there was still a certain gap between the actual teaching effect and the pre-class presupposition. For example:
1. When dealing with the question of why decimal points must be aligned, there is no time left for students to think and communicate, and students cannot express their understanding by combining the actual price or the meaning of decimal points.
2. The regulation of the whole class time is not good, and the previous links are loose, which leads to no time to deal with the later exercises.
For this lesson, there is still a little confusion: when creating a situation, I use price to present it, but I know that the price expressed by one decimal place is not standardized. Will using this non-standard price presentation give students an unreal feeling? What kind of situation can present all kinds of situations in decimal addition and subtraction?
Reflections on the Teaching of "Decimal Addition and Subtraction" 3 Decimal addition and subtraction begins with reviewing the calculation method of integer addition and subtraction. The simple calculation of decimal addition and subtraction comes from the knowledge transfer of integer calculation. It is not difficult for students to make a natural transition, but the range of numbers has expanded and students feel a little strange. However, in real life, many students already have the experience of decimal calculation and their own methods when shopping, so I began to create shopping situations in the classroom, which narrowed the distance between students and new knowledge from daily life and fully mobilized students' learning enthusiasm. At the same time, students ask questions, try to solve problems, and finally summarize the operation of decimal addition and subtraction to master the correct calculation method. Guide students to fully display their thinking and pay attention to cultivating students' ability of generalization, induction, analysis and application.
Vertical calculation is a common method in decimal addition and subtraction. It has many similarities with the addition and subtraction of integers, but there are also differences. I positioned the focus and difficulty of this lesson as "the column should be vertically aligned with the decimal point". The same numbers are well aligned, especially the integer can't find the decimal point, so there is no actual situation to rely on. At this time, I guide students to put the formula aside (meta) under specific circumstances. Money is a problem that people care about and often encounter. Here, I ask the students to discuss how to calculate vertically, why to do this, and how to align the numbers (that is, what is the significance of decimal point alignment) or not? Why? By discussing how to convert them into decimals with the same number of digits, it is easy to align and add and subtract. After the students are arranged vertically in this way, the correct rate is obviously improved.
In the process of practice, I show the difficulty of the exercise questions in a ladder shape, which reduces the difficulty from shallow to deep and improves students' interest in inquiry. When designing exercises, we also rely on students to write their own formulas according to their hobbies, follow the students' ideas, and take the students' thinking highlights as "excavation points". In this class, I try to affirm the advantages of children, such as clear thinking, orderly explanation, careful writing and calculation and other excellent learning qualities. At the same time, in teaching, I often let students use what they have learned to solve practical problems in life, so that students can grasp what they have learned in time in the process of practicing mathematics and realize the value of mathematics learning, thus enhancing their confidence in learning mathematics well, learning to look at things around them from a mathematical perspective, thinking about things around them and expanding the field of mathematics learning. Make students truly realize that "mathematics is useful, so use mathematics", thus stimulating students' interest in learning.
By teaching this course, I have a new understanding and improvement of teaching work. Classroom is the source of students' knowledge and the stage for students to show their personality. I will continue to improve my teaching quality and professional quality. It is precisely because of some shortcomings in practice that I deeply reflect on my classroom and make me go further and more practical on the road of professional growth.
Reflections on the teaching of decimal addition and subtraction 4 "Mathematics Curriculum Standard" clearly points out: "Mathematics is closely related to life, and mathematics comes from life and serves life." In real life, many students have had their own experience and methods of decimal calculation when shopping, so I designed a shopping scene to explore the calculation method of decimal addition and subtraction. Through shopping, let students find the math problems in their lives and find the ways to solve them through their own personal observation. By feeling life, let students know that mathematics is around, cultivate students' interest in learning mathematics, and fully mobilize their existing cognition.
In teaching, I help students understand the principle of decimal point alignment and pay attention to cultivating students' ability of generalization, induction, analysis and application. This lesson focuses on the instruction of learning method: (1) How much does it cost to calculate * * *? Learn how to calculate fractional addition. (2) By how to change, how much is one project more expensive (cheaper) than another? Learn decimal subtraction independently and summarize the calculation methods of decimal addition and subtraction. In this lesson, the exercises in the book are all decimal addition and subtraction of one digit. Considering other situations, I added the calculation problems in this class, including the calculation problems of integer simplification. Students are often influenced by integer subtraction and align numbers at the end. Therefore, it is found through discussion that "when the decimal places of the minuend are less than the decimal places of the minuend, you can first add 0 to the end of the minuend to make the decimal places of the minuend as much as the decimal places of the minuend, and then calculate according to the calculation method of integer subtraction." This makes it easier to align. After arranging students vertically in this way, the correct rate is obviously improved. (3) Finally, observe and compare the similarities and differences between integer addition and subtraction and decimal addition and subtraction, and summarize the calculation methods of decimal addition and subtraction. Make everyone master the calculation method of decimal addition and subtraction, and lay a solid foundation for future study.
In short, in the process of mathematics learning, we should actively guide students to actively participate in and experience, let students construct knowledge through their own experience, understanding, absorption, internalization and thinking, let students think and exercise their thinking through experience, and develop their practical ability and problem-solving ability through experience.
Reflections on the teaching of decimal addition and subtraction. 20xx national rural teacher training class, I will prepare a lesson recording. Our topic is simple decimal addition and subtraction. Because this class is the content of Unit 8 this semester, it is late. In order to record the class, I choose to talk about this unit two days before the start of school. I talked about this lesson today because I have talked about it many times before. Although I'm a little worried about students' acceptability, I think it should go well. As a result, this class not only delayed time, but also the students' participation in the whole class was not high, so I was a little at a loss. I don't think I can guide, so I have to say it myself. As a result, the effect of this class is not good, so calm down and seriously reflect as follows:
First, insufficient preparation before class.
As a teacher, I think I said before this class that I made an empirical mistake when preparing lessons. I simply considered the whole idea of this class, but I didn't specifically design how to create situations to introduce new lessons. The situation created during the lecture is that Xiyangyang breakfast shop recruits cashiers, provided that the sum of Chinese and math scores in the final exam of last semester is calculated first, and who can be a cashier is worked out? I want to review the addition of integers through this situation, and then lead to the example of breakfast in the breakfast shop in this lesson. Due to insufficient preparation, the decimal addition introduced in this situation is a bit far-fetched and not closely related.
Second, the classroom language needs to be refined.
A good class needs a refined language. Students will understand the meaning and know how to do it after listening. Teachers should design how to ask each question and how students will answer it. Because of overestimating one's ability and insufficient preparation, the questions designed in class are always wordy and students still can't understand them. Inspirational language always looks pale and powerless. For example, how much is a cup of soybean milk and a steamed bread? Inspire students to use integer addition to calculate, and then get the calculation method of decimal addition, so I didn't guide it well. How many times have I asked what 0.5 yuan is? What is 0.7 yuan? Seeing that my classmates were at a loss, I had to say that 0.5 yuan =5 and 0.7 yuan =7, which led to a long waste of time.
Third, group cooperation is a mere formality.
Our mathematics classroom pursues the mode of independent cooperation and inquiry. The success of a class depends on the participation of students. So we advocate group cooperation. In class today, I carefully observed the cooperative learning of several groups and found that students can't study independently, so let students think about how to calculate. Many students copy formulas from books and don't understand them. I don't know how to discuss and explore when I work in a group. If the group leader does not play a guiding role, students with poor foundation will not participate.
After thinking, I decided that in order to teach this course well, I must make the following changes:
First, further study the teaching materials, write a good teaching design, and take every link of teaching into account, including how teachers ask, how students answer and how students guide.
Second, continue to temper the classroom language. In view of the written teaching design, I will try to speak more after class, say it once in each link, and consider the students' answers, and formulate my own guiding language to inspire students.
Third, the independent cooperative inquiry mode has been effectively implemented. An excellent and efficient classroom must use the mode of independent cooperation and inquiry to highlight students' dominant position. Let students learn to study independently and help each other with their peers. The group leader plays a leading role, helping the group members to study together and improving the classroom efficiency.
Through today's class, I found my own shortcomings and learned that experience alone is not enough. I want to study my business and teaching materials seriously and strive for a good class.
Reflections on the Teaching of Decimal Addition and Decimal Addition and Decimal Addition and Decimal Addition and Decimal Addition in this lesson is the content of Unit 7 in the second volume of Grade Three. In teaching, the overall feeling is smooth and students' thinking is active.
First, mathematics in life will bring endless interest to students.
In the introduction, I use the vertical calculation of integer addition and subtraction to promote students to have a better understanding of the vertical calculation of integer addition and subtraction, so as to stimulate students' interest in learning and let students actively participate in learning. In the new class teaching, I also introduced the life situations that students often encounter, and let students observe in groups through pictures, and found math problems in the process of observation, showing students a lively teaching situation. Let students truly appreciate the value of mathematics, so as to be closer to mathematics. In order to let students learn and use mathematics in combination with their own life experience, fully tap the prototype of decimal addition and subtraction in life, select life materials that students are interested in from many life examples, and properly integrate mathematics knowledge with students' life experience through creative labor. So you can make different levels of decimal addition and subtraction answers.
Second, improve students' cognitive ability in teaching practice
In class, familiar "life" situations lead to problems, and students' accumulated competition experience is used to ask and solve problems. Students' exploration must be active. Facing the key and difficult point of "why decimal points should be arranged vertically", organize students to have group discussions and cooperative exchanges. Starting from the understanding and expression of individuality, the calculation method of "decimal addition and subtraction" is independently refined. These learning points, which need to be summarized by teachers in traditional teaching, are discovered independently on the basis of students' full experience and feelings, and become the result of students' "re-creation" of knowledge. I also mastered the decimal point alignment in decimal addition and subtraction calculation, that is, the same number of digits should be aligned and then calculated according to the calculation method of integer addition and subtraction. Through teaching, it is found that students have a good grasp of the calculation method and the correct rate of column sag calculation is also high.
Third, the problems in teaching are mainly reflected in the following aspects:
1. Students are often influenced by integer subtraction, and align numbers at the end of the calculation problem that the reduced decimal places are less than the reduced decimal places. To this end, students are guided to discuss through examples, and it is found that: "When the decimal places of the minuend are less than those of the minuend, you can first add 0 to the end of the minuend so that the decimal places of the minuend are as many as those of the minuend, and then calculate according to the calculation method of integer subtraction." This makes it easier to align. After arranging students vertically in this way, the correct rate is obviously improved; This method must be remembered when making mandatory demands on students.
2. At the same time, I also expanded the types of questions to strengthen students' adaptability, such as: 7.3+3.24=, 5. 1+3.35=, and so on. And through these topics, the calculation method of decimal point is highlighted. Make clear the key points and difficulties of this lesson.
Reflections on the teaching of decimal addition and subtraction 7 decimal addition and subtraction are taught on the basis of students' learning the meaning and nature of integer addition and subtraction and decimal. Decimal addition and subtraction and integer addition and subtraction are the same in meaning and calculation method, but the range of numbers has expanded, which is a bit strange to the students. The classroom begins to create situations, which are both real and attractive, making students feel that decimals are around us. Decimal addition and subtraction also exist in daily life, which brings students closer to new knowledge and fully mobilizes their learning enthusiasm. At the same time, the refined mathematical problems go straight to the center. Students ask questions, try to solve problems, exchange their own methods, summarize the operation of decimal addition and subtraction, and master the correct calculation method. The whole process embodies the interactive mode of "student-centered and teacher-led", which allows students to fully display their thinking and pay attention to their successful learning experience. In order to better consolidate the basic knowledge and skills, the practice should be arranged in a hierarchical and step-by-step manner, and expanded and extended appropriately.
The teaching of decimal addition and subtraction aims to make students experience the process of decimal addition and subtraction in writing, understand and master the writing methods, and understand the application value of decimal addition and subtraction in combination with life, thus improving students' thinking ability and learning ability. In teaching design, teachers should grasp the starting point of teaching according to students' life experience and existing knowledge, so that students can explore new knowledge in their own attempts. This lesson is based on students' learning about integer addition and subtraction, the meaning and nature of decimals and simple decimal addition and subtraction. Students have considerable basic knowledge and knowledge transfer ability. () Let children try, explore and acquire knowledge by themselves in the teaching process. Maximize students' participation in the process of exploring new knowledge and participating in the process of knowledge formation. In the inquiry algorithm, every student has a successful learning experience, exercised the will to overcome difficulties and established self-confidence. When teaching the key and difficult point of "column with decimal point vertically", the two writing methods are compared and demonstrated, and students are organized to discuss in groups and ask questions from each other. Making use of students' questions, keeping close to the teaching focus, guiding students to contact with existing knowledge and experience, conducting in-depth discussions and debates, inspiring and learning from each other, and independently refining the calculation method of decimal addition and subtraction are conducive to cultivating students' autonomous learning ability. The content of the exercise returns to life. "Shopping receipts in shopping malls", a familiar thing for students, allows students to discover the mathematical problems in life, let them know that mathematics is around them by feeling life, and cultivate their interest in learning mathematics. Understand the meaning of mathematics from life.
In teaching, teachers should often let students use what they have learned to solve practical problems in life, so that students can grasp what they have learned in time in the process of practicing mathematics and realize the value of mathematics learning, thus enhancing their confidence in learning mathematics well, learning to look at things around them with mathematical eyes, thinking about things around them and expanding the field of mathematics learning. Make students truly realize that "mathematics is useful and mathematics should be used", thus stimulating students' interest in learning. In short, in the process of mathematics learning, we should actively guide students to participate in and experience, let students construct knowledge through their own experience, understanding, absorption, internalization and thinking, let students think through experience, understand through thinking, and improve their ability to apply knowledge through understanding. Cultivate the ability to solve problems in practice.
Reflections on the teaching of decimal addition and subtraction 8 This part is based on the fact that students have learned the meaning of integer addition and subtraction, the meaning and nature of decimals. In real life, many students have had their own experience and methods of decimal calculation when shopping, so I designed a scene of collecting shopping receipts to explore the calculation method of decimal addition and subtraction. Through shopping receipts, students can find out the mathematical problems in their lives and look for solutions through their own personal observation. By feeling life, let students know that mathematics is around and cultivate students' interest in learning mathematics. Cultivate students' awareness and ability to cooperate with others in problem-solving activities. Through the addition and subtraction of decimals, we can cultivate students' rigorous, serious and meticulous scientific attitude.
In teaching, teachers help students understand the principle of decimal point alignment and pay attention to cultivating students' ability of generalization, induction, analysis and application.
This lesson focuses on the instruction of learning method: (1) How much does it cost to calculate * * *? Learn how to calculate fractional addition. (2) Encourage students to use various forms for calculation, and finally come to the conclusion that column and vertical calculation is more suitable. Because no one here has found other methods, it is not reflected. (3) Through how to change, they learn decimal subtraction independently and summarize the calculation method of decimal addition and subtraction. (4) Finally, observe and compare the similarities and differences between integer addition and subtraction and decimal addition and subtraction, and summarize the calculation methods of decimal addition and subtraction. Make everyone master the calculation method of decimal addition and subtraction, and lay a solid foundation for future study.
In addition, because shopping in the supermarket is limited, I also arranged the addition and subtraction of non-two decimal places at the back, for example: (1) The teacher was going to travel, and she bought a bag of French fries, 3.2 yuan, a bag of juice 1.95 yuan, and a kettle for 6.48 yuan. Has the teacher run out of money? How much money should I get back if I don't use it up? Xiaoming bought 0.853kg banana and 1.04kg strawberry. How many kilograms are bananas and strawberries? How many kilograms are bananas less than strawberries? Make up the defects of the topic and let students understand that there are other types of decimal addition and subtraction. This is also an extended problem, an attempt of addition and subtraction. However, due to time, I only did (1) questions, and I didn't have the opportunity to do (2) supplementary exercises. The reason is that I didn't fully estimate the time and the pace was slow. When learning addition, you should learn subtraction first, and then practice, which makes many students delay the calculation of addition.
Reflections on the teaching of decimal addition and subtraction 9 "Simple operation of decimal addition and subtraction" is based on the study of decimal addition and subtraction, and serves to solve the problem of decimal addition and subtraction in life and learn decimal elementary arithmetic in the future. Therefore, in teaching, we should first create situations for students to guess, and actively look for materials to verify, and then expand and reflect in further application, so that students can understand mathematics knowledge and make progress and development in thinking ability, emotional attitude and values.
In order to make the operation of the example "reasonable" and reflect the rigor of mathematics to a certain extent, students are mainly required to verify two laws themselves: the addition law of integers is also applicable to decimals, and the subtraction property of integers is also applicable to decimals, and then simple operations are carried out by using the operation law.
At the beginning of the class, I asked the students to review first, mainly about the comparison between calculation and addition and subtraction. Among these formulas, there are two formulas for exchanging the addend position and changing the operation order, the continuous subtraction formula and the continuous subtraction formula for the sum of two numbers. Then let the students observe the characteristics of these formulas, and give some similar examples to verify that some laws and properties in integers are also applicable to the addition and subtraction of decimals. This has laid a certain foundation for the simple calculation of decimals, and the past knowledge is slowly presented in the students' brains, one by one more complete.
Then, first take out the textbook examples for students to try (not to mention the requirement of "simple calculation"), and then ask questions after trying. What is the basis of your calculation? Then let the students "look at how to solve this problem in the textbook" to help them understand the necessity of explaining "the same application" in the textbook first. However, in actual teaching, students' speeches unexpectedly appear. At that time, his speech was not necessarily the result of careful consideration, but more to prove that "sequential calculation" was the right reason. I use this contract to grasp "can it be calculated like this?" This question causes students to discuss and exchange, and make a summary.
With addition, simple calculations can pave the way. Students naturally think of using the nature of subtraction to calculate the subtraction of decimals. Students try to find the calculation easier.
Then consolidation exercises. The first is "Find out which two decimal places are good friends". This exercise is mainly for students to practice rounding. Then there is "fill in the appropriate numbers in brackets so that the problem can be solved easily." Finally, it was used. It should be said that the level of the whole exercise is relatively clear, which makes the exercise achieve its goal.
The level of the whole class is clear and the teaching objectives are well achieved. In the teaching process, students are allowed to explore and verify independently, and the process from "passive learning" to "active learning" is completed, but there are some shortcomings in details. Because the simple calculation method of decimal addition and subtraction is actually based on the simple calculation of integers, the pace can be accelerated in the simple calculation method. What students tend to ignore is the observation and analysis of decimal data, so they can put forward rounding exercises when reviewing and introducing. They can round a decimal first, and then give a list of numbers to further consolidate the results. Give students an opportunity to communicate with teachers and students, and let him sum up the points for attention when rounding decimals: when rounding, you really can't just look at whether the last digit can make up an integer. It also depends on whether their decimal parts have the same number of digits.
In addition, as a teacher, we should establish the concept of dynamic generation, grasp the favorable opportunity and use effective strategies to fully transform random events in the classroom into teaching resources. Use the resources explored by students to show the process of knowledge generation.
Reflections on the teaching of decimal addition and subtraction 10 The simple calculation method of decimal addition and subtraction is actually based on the simple calculation of integers, so the pace of simple calculation can be accelerated. What students tend to ignore is the observation and analysis of decimal data, so they can put forward rounding exercises when reviewing and introducing. They can round a decimal first, and then give a list of numbers to further consolidate the results. Create opportunities for communication between students and teachers, and between students and students, so that they can sum up their own considerations about rounding decimals: when rounding, we really can't just look at whether the last person can make up an integer. It also depends on whether the digits of the whole decimal part are the same.
Success:
Students know in practice that the operation law of integer addition and the nature of subtraction are also applicable to decimals. Therefore, in this class, students consciously use simple calculation in calculation, and students have no difficulty in learning, learning new knowledge is very smooth, and the consolidation of exercises is also very smooth.
Disadvantages:
Using the operation law of addition to simply calculate decimals, students make fewer mistakes, but they make more mistakes in the nature of applying subtraction. For example: 7.3-4.8+ 1.2 and 12.89-(6.89+2.3). Therefore, in the teaching of new knowledge, it is necessary to design more exercises with subtraction and variation, so that students can solve problems flexibly.