1 Cultivate interest in oral calculation
Interest is the best teacher, so cultivating interest is the key. According to the age characteristics and cognitive rules of primary school students, the oral arithmetic training for students should start from the lower grades of primary school and start with interest.
1. 1 Strengthen intuitive teaching, attach importance to operation demonstration, and stimulate interest in oral calculation.
Thinking is constantly developing in the process of forming representations and concepts on the basis of intuition and carrying out cognitive activities such as analysis, synthesis, judgment and reasoning. Students' hands-on operation of learning tools is an important measure to implement intuitive teaching. In teaching, teachers can use multimedia demonstration, stick operation, picture collage and other intuitive demonstration means to understand reasoning through observation and operation, and closely combine operation with language expression, thus developing students' thinking and making students interested in the process of oral calculation. For example, in the teaching of the first volume, 9 plus several, through intuitive operation, students can make full use of the number of disks in their hands, which can be counted one by one, can also be counted from 9, or can be counted from 10. Then the teacher can demonstrate with objects (or classes). First, make 9 cartons into 10 cartons and fill one carton. Then, add 10 boxes to the carton, and add 3 boxes to the carton. One * * * is 13 boxes of drinks. Make students have a clear impression of "adding 9 to 10", let students experience the process of "adding 10", think while doing, help thinking with calculation, guide calculation with thinking, and cultivate students' thinking ability.
1.2 Carry out interesting exercises, play games and competitions, and arouse interest in oral arithmetic.
Students in lower grades are more active. In oral arithmetic teaching, interesting exercises and games can be used to compete, and games can be introduced into the classroom, so that they can get spiritual pleasure from success and promote students to form calculation skills in the competition. Such as "finding friends", "relay race", "delivering letters", "winning the red flag", "driving the train" and "seeing who can calculate accurately and quickly" enliven the classroom atmosphere and make students easily accept knowledge.
2. Strengthen thinking training and make clear reasoning.
The outline points out: "Mathematics teaching in primary schools should enable students to increase their knowledge and wisdom." Mathematics is the gymnastics of thinking. To teach students to learn and promote learning, we should "pay attention to students' thinking process of acquiring knowledge". "Oral arithmetic teaching should also pay attention to cultivating students' thinking ability and attach importance to and strengthen thinking training. How to strengthen thinking training?
2. 1 Provide ideas and teach thinking methods.
2. 1. 1 image method can report the answer quickly and accurately according to the formula, which is conducive to training the agility of students' thinking. If you use the multiplication formula directly, you must report the product or quotient in one breath.
2. 1.2
Split method
This method has the characteristics of clear organization, which is conducive to cultivating the orderliness of thinking. For example, the thinking process of "8+5= 13" is as follows: ① Thinking about 8 adds up to 10(8 plus 2); (2) How many and how many are five? (2 and 3); (3) Take 8+2= 10 and add 3. The rule of "carry addition within 20" is: "Look at large numbers (addition), divide by decimals, do ten first, then add".
2. 1.3 Simple algorithm (skill method) Number addition, subtraction, multiplication and division can be based on the operation rules of addition, subtraction, multiplication and division, the operation properties of addition, subtraction, product and quotient. According to the principle of equivalent transformation and the characteristics of numbers, the operation order can be changed or the "rounding" method can be used for simple operation to improve the operation speed.
(1) grouping method. According to the operational nature of the operational law, first calculate the numbers that can be added to whole ten, whole hundred and whole thousand in the formula, and then calculate the following numbers. If 345+75+55, the formula can be changed to (345+55)+75.
(2) Complement grammar. For a number close to whole ten, whole hundred and whole thousand, you can first add a number to it to make it whole ten, whole hundred and whole thousand, and then subtract the added number. For example, 420+99 = 420+100-1; 40× 19=40×(20- 1)
(3) decomposition method. In some multiplication and division operations, the known number can be properly decomposed, and then the algorithm or properties can be applied to make the calculation simple and convenient, and then the oral calculation can be carried out. For example, 16×25 can be decomposed into 4×4, and the original formula becomes 4×(25×4).
Simple methods are more flexible. For all kinds of calculations encountered in practice, we should flexibly use various thinking methods of oral calculation according to the characteristics of formulas and numbers, convert the original formulas into simple formulas, and then do oral calculation.
2.2 Explore a reasonable and flexible algorithm to cultivate the flexibility of thinking.
Curriculum standards advocate the diversification of algorithms, emphasize the importance of oral calculation, and have certain requirements for the speed of oral calculation. In order to improve the speed of oral calculation, the algorithm must be optimized. Only by mastering efficient calculation methods can students have a certain speed of oral calculation, lay a good foundation for later written calculation, lay a solid foundation for subsequent study, and realize the sustainable development of students in mathematics learning. Therefore, when the algorithm is diversified, there should be comments and choices, and the best method should be chosen, so that students can learn to choose the best and use it well from an early age. For example, teaching oral arithmetic of integer ten and integer one hundred times one digit, aiming at the formula 10×2= (
), the teacher asked the students to use their favorite methods to calculate without guidance. Students have many algorithms, ①10+10 = 20; ②2+2+2+2+2+2+2+2+2+2=20; ③ 1 multiplied by 2 has two tens, which is 20; ④ Calculate 1×2=2 first, and then add1"0" after 2 to get 20. At this time, the teacher was in no hurry to optimize the algorithm immediately, and two more questions were raised, 10×9 and 30×8. Are you still willing to use your own method to calculate? Why? So as to consciously guide students to simply reflect, compare, classify and adjust methods, realize the gap and form domestic demand, and algorithm optimization is imminent. Most students will choose the most commonly used algorithm to calculate. This process itself is also a process of divergent thinking. By comparison, we can develop students' thinking, improve their self-awareness and cultivate their awareness of optimization. It has achieved the goal of "removing the false and retaining the true, removing the rough and selecting the fine". Moreover, once students master the best method in the process of reflection and comparison, the speed of oral calculation will be greatly improved. Therefore, the diversification and optimization of the algorithm are not contradictory, they are unified, and they are both the process of students' active exploration.
2.3 the use of knowledge transfer, to guide the discovery of laws, to cultivate agile thinking.
Once the law is discovered and mastered by people, it will become a huge material force. In the teaching of oral arithmetic, teachers should pay attention to the study of teaching materials, explore the regular contents in the teaching materials, provide students with a breakthrough in thinking in time, guide students to think actively, independently discover the laws of knowledge, explain the truth, master methods and acquire oral arithmetic skills. For example, when teaching the multiplication formula of 9, first guide students to see how the multiplication formula of 9 is arranged vertically. After students discover the rules, they are asked to think about them horizontally. Through observation, students soon find that when you multiply 9 by several numbers, the number on the tenth digit is less than several numbers 1, and the number on the single digit and the tenth digit adds up to 9. In the process of discovering laws, students' memory and thinking ability have been exercised.
In the teaching of oral calculation, teachers should not only guide students to discover the rules, but also guide students to explore new oral calculation methods through discussion and exchange, using the law of knowledge transfer. In addition and subtraction teaching within 10,000 yuan, analogy reasoning can be used to let students acquire knowledge actively. For example, on the basis of reviewing "40+30" and "70-30", guide students to conclude that the addition and subtraction of integer decimal is a verbal calculation of integer decimal. Then, gradually analogize to "400+300", "700-300", and even analogize to "4000+3000" and "7000-3000", from which to draw inferences, so as to master the general oral calculation methods of integer hundreds and thousands addition and subtraction. three
Strengthen oral arithmetic training and improve calculation ability
In the lower grades, oral arithmetic should not only be correct, but also have certain speed requirements, which requires teachers to do oral arithmetic training. Not only should the training form be diversified, but also it should be graded, from shallow to deep, from simple to complex, and the persistence of training should be maintained.
3. 1 Regular targeted training, enriching practice forms and improving oral calculation ability.
The formation of speech skills was not built in a day. Speech training should be regular, and the requirements for speech calculation should be gradual. Therefore, special efforts are needed for training. However, it is also necessary to arrange training regularly and set goals, and arrange teaching progress reasonably, so as to make oral arithmetic training persistent and achieve the purpose of improving computing ability. In every math class, teachers should organically infiltrate the teaching of oral arithmetic into all aspects of teaching, and the methods of oral arithmetic practice must be diversified and interesting, so that students will not feel monotonous and boring. Common oral arithmetic practice methods include visual arithmetic (oral arithmetic cards and tables), listening arithmetic (checking passwords), oral arithmetic games (winning red flags and driving trains) and so on. In oral arithmetic practice, teachers should flexibly use the above methods according to the teaching purpose and requirements, combine visual arithmetic with listening arithmetic, practice in various forms, and practice frequently in scattered concentration. For example, cards can be used to organize various practice methods, and relay races can be held. The teacher gives each row a number card with 7-8 questions printed on it (depending on the number of people in each group). After the first student finishes a problem, he quickly passes it on to the next student, and so on, to see which line the last student passed the number card to the teacher first, and the calculation result is correct, even if it is a victory. You can also count each other on the table and drive the train.
You can also organize students to hold oral arithmetic competitions, so that students can taste the joy of success and improve their oral arithmetic skills. In order to make children pay attention to themselves, I held a week, a month and a semester oral arithmetic competition. In order not to waste paper and improve the recycling rate of oral calculation training paper, I determine the content of oral calculation every month and give students a oral calculation training paper (5 minutes, 50 problems) for training twice a week. The specific operation is that when students do oral arithmetic training, the number of oral arithmetic is not written directly on the oral arithmetic training paper, but on another piece of white paper, so that the training paper can be recycled. After completion, the teacher tells each student the time to complete the training, and records each student's score and time by proofreading the score in groups of four and correcting it by the teacher. The top five students with the strongest comprehensive ability (speed+score) are selected for each training. At the same level, a quick calculation competition is held once a month, and the usual training methods are also adopted, and excellent certificates are issued. At the end of each semester, there is an oral test of the same level (5 minutes, 60 courses), and students can do as much as they can in the specified time. All students are not required to complete 60 questions in 5 minutes. That is, there is no hard and uniform requirement for the speed of oral calculation, but it basically reaches 7-8 questions per minute. Students who fail to meet the requirements in the test can be re-evaluated. Teachers can make and issue the Grade Certificate of Oral Computing Ability in the Third Grade of Primary School for students according to the following standards.
Get more than 55 correct answers in 5 minutes-"Super Word Count Expert"
More than 50 correct answers in 5 minutes-"oral calculation level 3"
Make more than 40 correct answers in 5 minutes-"oral calculation level 2"
Do 35-40 correctly in 5 minutes-"oral calculation level 1"
At the same time, teachers can also take some ways: for example, count the accuracy of students' calculations, (do a few questions in 5 minutes, do a few questions correctly, and evaluate them according to different situations. ) so that students have a sense of innovation, so that students gradually develop a serious and careful habit.
3.2 Classification and comparison training
When training with the same type of verbal arithmetic, it is easy to be confused. Pay attention to the analysis and comparison, such as 15-6 and 16-5, 28-2 and 28-20. This comparative exercise not only consolidates the verbal skills, but also cultivates students' observation and attention. Practice oral arithmetic problems that often make mistakes many times, combined with error correction exercises. You can write down the typical and representative error boards in the exercise, so that students can point out the mistakes, explain the reasons and correct them. For example, 80×5÷80×5= 1, 54-54÷6=0.
3.3 memorize some commonly used data, strengthen the connection between oral calculation and written calculation, and comprehensively improve the calculation ability.
Such as: 25×4= 100, 125×8= 1000.
3.4 Family-school education
If parents want their children to have quick reaction ability, it will get twice the result with half the effort if they spend a few minutes practicing oral arithmetic with their children before and after meals, and then cooperate with appropriate rewards. Encouraging children to participate in necessary social practice activities, for example, helping parents to calculate the amount of money spent when shopping with their parents, is also an effective way to cultivate students' ability of calculation and reaction, which can stimulate and cultivate children's interest in learning mathematics.
3.5 Cultivate students' earnest and diligent learning attitude and calculating habits of careful calculation and standardized writing.
Cultivating students' serious, strict and diligent learning attitude and good calculation habits is the requirement of teaching syllabus and the important content of strengthening quality education. A large number of facts show that the lack of serious study attitude and good study habits is one of the important reasons for students' calculation errors. Therefore, in order to improve students' computing ability, we must pay attention to the cultivation of good computing habits, especially for junior students, and we must strictly require students to carefully write Arabic numerals and operational symbols, write correctly, do not scribble, alter or paste, and keep their homework clean and beautiful. Make students develop a rigorous, serious and meticulous learning attitude and a spirit of perseverance and courage to overcome difficulties.
In a word, oral mathematics teaching is both a foundation and a difficulty for junior students. From the first grade of primary school, it is necessary to cultivate students' oral mathematics ability. Therefore, in the teaching process, teachers should strive to tap students' potential, stimulate students' interest in learning, persistently use various forms and methods, and strengthen training for a long time, so that students can calculate skillfully and quickly, with flexible methods and correct results, improve students' thinking ability and make them understand mathematics.