The abdication subtraction within 20 is taught on the basis of learning addition and subtraction within 10 and addition within 20. In the previous study, most students have a learning foundation. Some of them have received this kind of training in kindergarten, and some parents are teaching their children to use spanner fingers. Therefore, the difference between children learning this part of knowledge is only the difference in calculation speed. Most children can work out the numbers by themselves. \x0d\ \x0d\20 Teaching of abdication subtraction When teaching "ten minus nine", I asked the children to discuss and communicate, and got two calculation methods, one is "doing subtraction and adding" and the other is "breaking ten". After class, I learned that only a few children have mastered the algorithm. What I can't stand most is that some students are still using wrenches to calculate. There is communication in teaching. Why do only a few people know arithmetic? I reflect on my classroom: I think from the students' listening habits and the implementation of communication. Although there is a new curriculum concept of cooperative learning and independent communication, I only pay attention to those children who can learn actively in class. Those children who sit in the classroom and have no consciousness of listening to the class can't learn anything at all in one class. Tell them to get up and reason. What did they say? And those timid children who dare not answer questions. Do I care about them? I thought it over and felt the seriousness of the problem. Under such a learning situation, how can I carry out the following teaching? At present, the most important thing is how to mobilize children's enthusiasm for classroom learning and how to cultivate children's awareness of attending classes. \ x0d \ x0d \ In the next teaching, I want to train students to speak arithmetic (mainly to master the arithmetic of "breaking ten methods"). I wrote the oral arithmetic process of "breaking ten methods" on the blackboard, and the group selected the most fluent children as the primary teachers to take other students to read. The four groups saw that there were more little teachers in that big group, so they added red flags to that group. In the training of reading algorithm, the form of winning the red flag competition has improved students' enthusiasm, and children all want to be primary school teachers. Through reading and oral training in a class, most students can say the arithmetic of "breaking ten" and subtracting nine from ten. The teaching of the third class made me feel much more relaxed. In class, I first practice the oral calculation of subtracting nine from ten, and then ask: We have learned more than ten subtracting nine from abdication within 20, have we finished the abdication subtraction within 20? The children thought for a moment and said, "No". That child can be a little teacher to test everyone? Children are interested in being primary school teachers. Many children actively participate in learning and experience the joy of success. \x0d\ \x0d\ Junior Mathematics Teaching Practice My conclusion is that we teachers need to try our best to cultivate their learning ability, especially to cultivate a good sense of attending classes. I will continue to work hard in the future teaching. \x0d\\x0d\ Reflection II: Reflection on the teaching of abdication subtraction within 20 years \ x0d \ x0d \ 20. The abdication subtraction within 20 is taught on the basis of students' knowledge of carry addition, addition and subtraction and 10 subtraction. There are three calculation methods for abdication subtraction within 20. The flat ten method and the broken ten method are one class hour, so I want to add and subtract them into one class hour. After two classes of teaching, students have not mastered the calculation method of abdication subtraction within 20. \ x0d \ x0d \ The textbook adopts the situation of "forest restaurant", which turns the problem of 13-6 into the problem of how to get six cups, which is closer to students' lives, and most students have their own methods. Different ways of taking cups correspond to different calculation methods. It is not difficult for students to hold cups, and students can express their ideas clearly. The key is to transform the idea of holding a cup into a calculation method, and students experience a mathematical process in this process. With the help of the situation, let the students understand the calculation principles of "breaking ten methods" and "leveling ten methods", and then let them practice choosing one of them to calculate. After the calculation, let the students say the method first, then demonstrate the calculation method with a stick to help the children understand it, and then let the students say the calculation method, which number to divide first and how to divide it. What about after division? When talking about the calculation process, it is often the time when the discipline is the worst, and many students are unwilling to listen. At this time, giving a "math star" to the students who listen carefully and giving oral praise loudly can set an example for other students, but it can't last long. Teachers should listen in all directions, keep an eye on all directions and seize available resources at any time. Mathematical knowledge has its inherent logic. Students have gone through the process from image to abstraction, from life to mathematics, and built their own knowledge system, so that every child can understand the arithmetic of abdication and subtraction within 20 years. Because each child's knowledge reserve and experience accumulation are different, different children will have different ways to solve the problem of 13-6. On the basis of various algorithms, combined with their own judgment, understanding and internalization, different children may be promoted differently on the original basis. Therefore, in practice, students also show different requirements in the choice of methods. Children with strong ability can choose to calculate directly, while children with weak ability need to use learning tools such as sticks to calculate. \ x0d \ x0d \ Addition and subtraction method is easy for students to find, and it is also used more in usual calculations, because addition is a positive operation, which conforms to students' cognitive law. However, students are required not only to have such a perception of numbers, but also to gradually realize that there is such an addition and subtraction relationship between numbers through certain training. This is the addition and subtraction relationship to be learned later this semester, which is infiltrated and nurtured in this class. In practical teaching, the method of "addition and subtraction" is based on students' special proficiency in carry addition within 20 years. If students are particularly skilled in the calculation of carry addition within 20, they will find the method of "addition and subtraction" very simple. However, after a winter vacation, all the children had a happy New Year, and all the oral arithmetic exercises were forgotten. The addition and subtraction within 10 and the carry addition within 20 I learned last semester are almost forgotten. Therefore, it is particularly difficult for such children to learn to use the method of "adding if they want, and reducing if they want". \x0d\\x0d\ According to these characteristics of students, after learning these three calculation methods, I asked students to choose one of them for calculation. In fact, the purpose of advocating algorithm diversification is to promote students' individualized thinking, carry out mathematical communication, encourage the exploration of different calculation methods and promote students' development, rather than requiring students to master multiple calculation methods. In addition, I pay attention to let students practice oral arithmetic every day. Based on the addition and subtraction within 10, they can calculate the result quickly and accurately, and then practice the carry addition within 20. After the carry addition within 20 is very skilled, try to calculate the abdication subtraction within 20 by addition and subtraction. \x0d\\x0d\ Reflection on the teaching of abdication subtraction within 3: 20 Reflection on abdication subtraction within 20 \ x0d \ x0d \ 20 is based on learning 10 addition and subtraction and addition within 20. In the previous study, most students had a learning foundation. Some of them have received this kind of training in kindergarten, and some parents are teaching their children to use spanner fingers. Therefore, the difference between children learning this part of knowledge is only the difference in calculation speed. Most children can work out the numbers by themselves. \ x0d \ x0d \ In teaching this unit, I emphasized the following points: \ x0d \ x0d \ 1. Introduce the old into the new, "add up after calculation." \x0d\\x0d\ Students need to apply the carry addition within 20 when calculating the abdication subtraction within 20, which is the so-called "subtraction but addition". Therefore, in the new teaching class, I always do the corresponding oral calculation of carry addition to awaken children's memory of carry addition and show the formula for finding unknown addend, paving the way for students to explore the bridge of abdication and subtraction within 20 years. Such as: 9 +( )= 13, 13-9 =\x0d\\x0d\ 2. Cooperative inquiry to strengthen the learning process. \x0d\\x0d\ 1, hands-on operation. I added a link for students to operate in class. Every two people have a set of sticks, and the teacher gives the specified formula, such as: 13-9= student operation; Interoperability between deskmates. Then discuss column calculation. In this way, students not only consolidate the new knowledge they have learned in class, but also further understand the significance of subtraction in the process of cooperative learning, and initially infiltrate the structure and solving methods of subtraction application problems, laying the foundation for subsequent learning. \x0d\\x0d\2。 Learn to break ten methods. When students learn to break the ten laws, I first let them know what the ten laws are. The minuend is greater than 10, and the number in the unit is not reduced enough. For example, 13-9= at this time, the minuend is broken (disassembled), one of which must be 10 and the other must be 3. It is enough to subtract 9 from 10, and it will soon be 1, and then add 1 back to another part, 3, 1+3 = 4, so 13-9=4. Let students know the benefits of learning ten methods, so as to make the calculation more convenient, easier and more accurate. \x0d\\x0d\ Third, encourage diversity of algorithms. \ x0d \ x0d \ Some students can actually make up a formula: 1, 3+ 1 = 4 when they see 9. Some use a little method. Some experts have suggested that because children have different intellectual backgrounds and life experiences, the method suitable for them is the best. When learning to subtract more than nine from ten, students mainly master the method of breaking ten and want to add and subtract. Then students can easily learn to subtract eight, seven, six, five, four, three and two from more than ten. Teachers can let students learn independently, and some students can demonstrate the process. \x0d\\x0d\ IV。 What I can't do \ x0d \ x0d \ pays too much attention to class time and deprives students of the right to seek knowledge independently, which is also my most common mistake. If children are given enough time to experience, dress, speak, communicate, feel and really express their thoughts and processes, I think this is the process of students' internalization. Every time I read new content, I feel that I have less time to pay attention to students with learning difficulties. \x0d\\x0d\ Reflections on the teaching of abdication subtraction within 4: 20 \ x0d \ x0d \ The teaching content of this unit is abdication subtraction within 20, one is subtraction that needs abdication after more than ten subtractions, which is referred to as abdication subtraction within 20 for short; The second is to solve a simple practical problem, that is, "using mathematics", with abdication subtraction within 20 and carry addition learned before. Therefore, when learning this part of the content, students must learn the calculation method on the basis of understanding arithmetic, and achieve a certain proficiency through reasonable practice, so as to lay a solid foundation for future study. \x0d\\x0d\ 1。 Hands-on operation enriches perception \ x0d \ x0d \ People think with sensory materials. Students should also make full use of sensory organs and learn materials through intuitive image perception when accepting the knowledge summarized by predecessors. In the teaching process, every time students learn a new knowledge, I pay great attention to making full use of intuitive means to enrich students' perceptual materials. Let their eyes, ears, mouth, hands and brain participate in teaching activities. The characteristics of first-grade pupils are concrete thinking in images, short attention time, love to talk and love to move. In teaching, I should fully consider the age characteristics of students, guide students to do more work, use more brains and talk more, and mobilize all kinds of senses to participate in learning activities.