First, use your hands and brains to establish a visual demonstration to help with oral calculation.
The transition from direct perception of physical objects to representation operation is an important form of oral arithmetic in lower grades. So since students know the number within 10, I have been paying attention to intuitive teaching. Before class, teachers and students prepared many pictures and sticks that students liked. In class, let students count pictures and sticks, and then count their little fingers to strengthen the training of number sense. Then, through the intuitive operation activities of division and merger, I can establish the representation, master the composition and decomposition of numbers within 10, skillfully add and subtract numbers within 10, and then establish the representation of carry addition 9+2. Here's what I did: first, I showed nine balls in the box and two balls outside, and then I thought about it. How can you tell at a glance how many * * *? The students quickly came up with an idea and said, "I'll take out the 1 in these two and put it in the box, so that there is 10 in the box, 1 outside and a * * *1." I fully affirmed and praised the students' answers and explained to them that this method is called "add up to ten". When I saw 9, I thought that the sum of 9 and several was 10. On this basis, I immediately said a few: 8+3=? ,9+4=? ..... The students answered questions like water, and accurately spoke the method of rounding off ten, which not only established the representation but also improved the accuracy of oral calculation.
Second, pay attention to arithmetic teaching and speed up oral calculation.
The basic teaching of oral calculation lies not in the simple pursuit of oral calculation speed, but in students' reasoning. Only by clarifying reasoning can we effectively master the basic methods of oral calculation. Therefore, we should attach importance to the teaching of mathematical theory. For example, when teaching 8+4= 12, we should start with the actual operation to make students understand: "4 can be divided into 2 and 2, 8 and 2 constitute 10, 10 plus 2 constitute 12." And draw a thought process diagram of 8+4= 12. On the basis of students' full understanding, simplify the thinking process and abstract the law of carry addition: "Look at a large number, divide it into decimals, make it 10, and add a few more." Finally, guide students to think about how to calculate "4+8", so that students can understand arithmetic and master the basic methods of oral calculation. Another example is the teaching of Zen subtraction within 20. At the beginning of class, display 16-9= () and ask, "How much is 16 minus 9?" The students scrambled to answer: "it is equal to 7." I asked again, "How did you come up with it?" Some students said: "Because 9+7= 16, so 16-9=7", I immediately praised: "That's great, this method is called" doing subtraction and adding ". I further led out: "Can you think of other ways to do this problem?" At this time, the students immediately became interested, and everyone was actively thinking. A student said, "I think so. Let's calculate 10-9= 1, and then 1+6=7. " Another student said, "I think so." Let's count 16-6= 10, then 10-3=7. " At this time, the students' ideas come alive and they all want to show their talents. After the students finished speaking, I showed different abdication subtraction methods in time, and asked the students to talk about the oral calculation process of different ideas. Through reasoning training, the method comes alive and the speed of oral calculation is accelerated.
Third, scientifically design training methods to consolidate and improve the ability of oral calculation.
Primary school students have strong thinking images, and it is difficult to form skills without reasonable training. I took the following measures in oral arithmetic training:
1, combining visual, listening and arithmetic training; Sighting and listening are two basic forms of oral arithmetic practice. It is regarded as the number of words spoken by seeing the topic; Listening and calculating need listening, memorizing and calculating, so numbers are difficult to calculate. In oral arithmetic, the forms of oral arithmetic often change. The combination of visual arithmetic and listening arithmetic can improve students' interest in oral arithmetic and keep their learning psychology in a positive state.
2. Contrast training between old and new knowledge. Although it is not difficult to do oral arithmetic in the lower grades, it is really not easy for all students to meet the requirements stipulated in the mathematics curriculum standards. Junior students accept new knowledge quickly, but soon forget it. In view of this feature, I often use the method of cross-practice of old and new knowledge in oral calculation to help them firmly master knowledge and improve their oral calculation ability. Practice the content in class first, and then review the old knowledge when the students basically master the new knowledge, so as to achieve the mutual connection and promotion of the old and new knowledge and form a complete knowledge system.
3. Diversified forms of training (1) Answering oral arithmetic questions The teacher wrote the oral arithmetic questions on the card in advance, and asked the students to answer the questions quickly by showing the card. Answering first can improve the speed of oral calculation and train the agility of students' thinking. (2) Cards help to find friends. Everyone prepares a set of digital cards within 20. In class, they will use these cards to play a game of finding friends according to the space they have learned. Everyone will take one. If the first two students show 8+4 with cards, who are their friends? (3) The game is oral. In training, we often use the form of "helping small animals find homes, finding friends hand in hand, and small postmen" to carry out oral arithmetic training to stimulate students' interest in learning and improve the speed of oral arithmetic. (4) The group oral contest won the red flag. This kind of practice can improve the sense of collective honor while cultivating the ability of verbal calculation. During training, the whole class is divided into four groups on average. The teacher shows three groups of formulas prepared, with ten questions in each group and ten players in each group. The teacher ordered to start at the same time. Only one piece of chalk is used in each group. The first person in each group is allowed to finish the first one, and the second student can win one. No matter which group is correct, it will win the prize soon, little red flag.
4. Decentralize power and concentrate on regular training. Improving students' oral expression ability is not a one-off event, but the result of long-term training. When teaching carry addition in 20 minutes, we should first concentrate on understanding the principle of carry, then practice 9 plus several, 8 plus several, 7 plus several ... Finally, we should concentrate on training and find out how to add 9 plus several and 8 plus several ... and arrange them regularly. In 20 years, students can concentrate on addition and subtraction, ask them to come up with two subtraction formulas according to an addition formula, and write two addition formulas and two subtraction formulas quickly according to the related three numbers 9, 6 and 15. In this way, through centralized-decentralized-centralized routine training, students can reach the degree of blurting out.
5. Evaluation mechanism is indispensable. In primary school mathematics classroom teaching, teaching feedback is a way to convey the teaching effect in time. No matter what kind of competition or game, teachers should carefully organize and evaluate it properly, so that all students can actively participate, pay attention to each student and let everyone have the opportunity to participate in practice. Every progress and encouragement of students is also the motivation for students to learn. The evaluation of speech ability is mainly carried out in different forms, such as classroom work, mathematics competition, speech competition and so on. For students who have a good command of oral expression skills, they should be praised and rewarded in time, and for students who still need to improve, they should be encouraged in time. For example, I will give a red flower to the classmate who completes his homework and competitions correctly and quickly every day, and a little star or a smiling face to the classmate who makes progress for the last time, accumulating enough ten flowers. I will give him an eraser or a pencil, and I will also give honorary certificates to the winners of the school oral arithmetic competition, and I will also give different rewards to the students who are making progress. I will also post some excellent homework on the honor roll regularly, so that students can get the joy of success in the atmosphere of teacher's encouragement and appreciation every day, so that students at different levels can feel the joy of success.
Oral arithmetic is a long-term teaching task. To really improve students' computing ability and verbal skills, we need to go through a process of understanding, knowing how to calculate, being skilled and dexterous. According to the age characteristics of students, flexible and diverse training forms should be formulated to stimulate students' interest in learning and entertain and educate. Only in this way can we truly achieve the goal of cultivating junior high school students' excellent oral expression ability. It is not an easy task to cultivate students' oral expression ability. It is important to practice every day, so as to gradually cultivate students' good oral expression habits and comprehensively cultivate students' oral expression ability.