Mining in Kunming, Yunnan
Publish: 2021-03-29 07:24:42
1. First, I must do more questions.
I must do more thinking questions.
Second, I must react quickly.
I must use a variety of formulas to calculate in my mind.
(this may be a little abnormal)
this is my own way to do calculation problems
I must do more thinking questions.
Second, I must react quickly.
I must use a variety of formulas to calculate in my mind.
(this may be a little abnormal)
this is my own way to do calculation problems
2.
Price list of Maotai North Cordyceps sinensis wine:
serial number proct name specification capacity market price (yuan / box)
1 Maotai North Cordyceps sinensis wine · blue diamond (new proct) 1 * 6 500ml 1280
2 Maotai North Cordyceps sinensis wine · golden diamond (new proct) 1 * 4 500ml 1580
3 Maotai North Cordyceps sinensis wine · golden diamond (new proct) The prices of the above Maotai liquors are retail prices in the market, for reference only, Subject to the actual store price and activity price
3.
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4. Computational ability is the basic ability for students to learn mathematics. It is the basis of learning mathematics. One of the main tasks of primary school mathematics is to cultivate and improve students' computational ability. The accuracy and speed of calculation will directly affect the quality of students' learning, Therefore, the teaching of calculation can not be ignored. How to improve students' calculation ability and make them calculate correctly, quickly, flexibly and reasonably? In the teaching work, I have made some discussions and research, and achieved some good results. I have summarized the following experiences:
first, to find problems and change students' understanding.
in order to make students realize the importance of calculation, I first carried out an activity among students: let students collect the mistakes they often make in calculation, and take two weeks as the standard, Each student can do it by himself or by working together in a group. After two weeks, record the staggered questions, including the reasons for the mistakes, who should look for them carefully and accurately. When the enthusiasm of the students is aroused, the problems will be shaken out:
(1) reading mistakes, ing mistakes and scribbling. 6 and 0, 1 and 7 are ambiguous
(2) when the column is vertical, the digits are not aligned
(3) no draft is made ring calculation
(4) one digit addition and subtraction calculation errors lead to errors in the whole question< There are two reasons for carelessness: one is that children's physical and psychological development is not mature enough; the other is that they have not formed good learning habits. The first is a natural growth process; the second is that corresponding methods can be adopted for training, Therefore, while guiding students to analyze the reasons, we should highlight the cultivation of students' good learning habits, which is the key to improve the ability of calculation and the basic requirement of quality ecation.
Second, cultivate students' good habit of calculation. Most of the errors in calculation are caused by carelessness, carelessness, scribble and other bad habits, Good calculation habit is the guarantee to improve the calculation ability. In the calculation training, students are required to do one look, two think, three calculate and four check.
1. Look: they are serious about logarithm. If the questions are copied wrong, how can the results be correct? Therefore, students are required to check with the original question or the previous formula in time when ing questions and calculating each step, so as not to wrong numbers or operation symbols; ② Check the numbers on the vertical type with those on the horizontal type; ③ In addition, the calculation must be accurate first, and then fast.
3. Calculation: write carefully Calculation. The writing of homework and exercises should be neat, not scribbled, and the format must be standardized. The writing of numbers, decimal points and operation symbols in the title should be in line with the standard, with proper intervals between the numbers, and the vertical type on the draft should be aligned and organized clearly. When calculating, you should concentrate your energy, not rush or rush.
4, First of all, we should check whether the calculation method is reasonable; Secondly, check whether the numbers and symbols are copied wrong, and whether the decimal point is written wrongly or omitted; Thirdly, we need to check and calculate every number and final result in the process of calculation. Therefore, cultivating good learning habits is an important way to prevent calculation errors and improve calculation ability.
thirdly, we need to cultivate students' oral calculation ability and lay a solid foundation, It is an important part of the calculation ability, so to improve the students' calculation ability, we must lay a good foundation for oral calculation.
1. In order to improve the accuracy and speed of students' oral calculation, I consciously ask the students to remember some special mathematical combinations according to the students' knowledge structure, such as: sum is the whole ten, the whole hundred (73 and 27, 98 and 2, etc.); The proct is two numbers (25) of the whole ten and the whole hundred × 4,125 × 8, etc.); The memory of these calculation results is not only of great help to improve the accuracy of students' calculation, but also greatly improve the speed of students' calculation.
2. Arrange exercises in each class. In each math class, according to the teaching content and the actual situation of students, choose an appropriate time, arrange 3-5 minutes of oral calculation exercises, and each student prepares a Book (practice oral calculation every day), 3. Various forms of transformation training, such as visual arithmetic training, listening arithmetic training, oral arithmetic, oral arithmetic games, "confrontation race", "relay race" and so on, to improve students' adaptability.
Fourth, strengthen the teaching of estimation
estimation can cultivate students' sense of number, and guide students to understand "operation" in depth, It can help students check whether the calculation result is correct or not. By using the estimation method, the calculation result can be positioned in advance, and the value range of the calculation result can be determined quickly. Through the estimation before calculation and the check after calculation, the errors caused by carelessness can be avoided. Students can see the last bit of the calculation result. If the bits are 3 and 8, the sum of the bits of the result is definitely 1, Multiplication must be 4, such as 13 × In general, students' mistakes in practice are interlinked and universal. Under the guidance of teachers, some are easier to correct and overcome, while others are more difficult to correct, Especially, this kind of mistake has taken root in my mind. Therefore, I am good at understanding and collecting the problems existing in the written calculation in my daily teaching, selecting common typical mistakes with foresight and pertinence, analyzing and communicating with students, and achieving the purpose of "treating" and "preventing" diseases through collective "consultation"; For those questions that are close and easy to make mistakes, contrast exercises are organized to overcome the negative effect of thinking set, To cultivate students' ability of comparison and identification.
I usually design the exercises for students in this way: judge right and wrong → find out the mistakes → analyze the causes of mistakes → correct → summarize the methods of preventing the same kind of mistakes; You can also do comprehensive exercises; All kinds of wrong questions can be printed on the homework paper and sent to students for correction in class, or students can take out their own homework book and wrong question book and re analyze and revise the wrong questions in their homework.
in a word, the cultivation of students' computing ability should be carried out in the whole process of primary school mathematics teaching, which not only strengthens the training of students' basic skills, but also improves the teaching efficiency, At the same time, we should also pay attention to the targeted training of students. As long as we carefully study, constantly summarize and improve our work, and seriously excavate the ability factors in the calculation problems, students' calculation ability will be improved
first, to find problems and change students' understanding.
in order to make students realize the importance of calculation, I first carried out an activity among students: let students collect the mistakes they often make in calculation, and take two weeks as the standard, Each student can do it by himself or by working together in a group. After two weeks, record the staggered questions, including the reasons for the mistakes, who should look for them carefully and accurately. When the enthusiasm of the students is aroused, the problems will be shaken out:
(1) reading mistakes, ing mistakes and scribbling. 6 and 0, 1 and 7 are ambiguous
(2) when the column is vertical, the digits are not aligned
(3) no draft is made ring calculation
(4) one digit addition and subtraction calculation errors lead to errors in the whole question< There are two reasons for carelessness: one is that children's physical and psychological development is not mature enough; the other is that they have not formed good learning habits. The first is a natural growth process; the second is that corresponding methods can be adopted for training, Therefore, while guiding students to analyze the reasons, we should highlight the cultivation of students' good learning habits, which is the key to improve the ability of calculation and the basic requirement of quality ecation.
Second, cultivate students' good habit of calculation. Most of the errors in calculation are caused by carelessness, carelessness, scribble and other bad habits, Good calculation habit is the guarantee to improve the calculation ability. In the calculation training, students are required to do one look, two think, three calculate and four check.
1. Look: they are serious about logarithm. If the questions are copied wrong, how can the results be correct? Therefore, students are required to check with the original question or the previous formula in time when ing questions and calculating each step, so as not to wrong numbers or operation symbols; ② Check the numbers on the vertical type with those on the horizontal type; ③ In addition, the calculation must be accurate first, and then fast.
3. Calculation: write carefully Calculation. The writing of homework and exercises should be neat, not scribbled, and the format must be standardized. The writing of numbers, decimal points and operation symbols in the title should be in line with the standard, with proper intervals between the numbers, and the vertical type on the draft should be aligned and organized clearly. When calculating, you should concentrate your energy, not rush or rush.
4, First of all, we should check whether the calculation method is reasonable; Secondly, check whether the numbers and symbols are copied wrong, and whether the decimal point is written wrongly or omitted; Thirdly, we need to check and calculate every number and final result in the process of calculation. Therefore, cultivating good learning habits is an important way to prevent calculation errors and improve calculation ability.
thirdly, we need to cultivate students' oral calculation ability and lay a solid foundation, It is an important part of the calculation ability, so to improve the students' calculation ability, we must lay a good foundation for oral calculation.
1. In order to improve the accuracy and speed of students' oral calculation, I consciously ask the students to remember some special mathematical combinations according to the students' knowledge structure, such as: sum is the whole ten, the whole hundred (73 and 27, 98 and 2, etc.); The proct is two numbers (25) of the whole ten and the whole hundred × 4,125 × 8, etc.); The memory of these calculation results is not only of great help to improve the accuracy of students' calculation, but also greatly improve the speed of students' calculation.
2. Arrange exercises in each class. In each math class, according to the teaching content and the actual situation of students, choose an appropriate time, arrange 3-5 minutes of oral calculation exercises, and each student prepares a Book (practice oral calculation every day), 3. Various forms of transformation training, such as visual arithmetic training, listening arithmetic training, oral arithmetic, oral arithmetic games, "confrontation race", "relay race" and so on, to improve students' adaptability.
Fourth, strengthen the teaching of estimation
estimation can cultivate students' sense of number, and guide students to understand "operation" in depth, It can help students check whether the calculation result is correct or not. By using the estimation method, the calculation result can be positioned in advance, and the value range of the calculation result can be determined quickly. Through the estimation before calculation and the check after calculation, the errors caused by carelessness can be avoided. Students can see the last bit of the calculation result. If the bits are 3 and 8, the sum of the bits of the result is definitely 1, Multiplication must be 4, such as 13 × In general, students' mistakes in practice are interlinked and universal. Under the guidance of teachers, some are easier to correct and overcome, while others are more difficult to correct, Especially, this kind of mistake has taken root in my mind. Therefore, I am good at understanding and collecting the problems existing in the written calculation in my daily teaching, selecting common typical mistakes with foresight and pertinence, analyzing and communicating with students, and achieving the purpose of "treating" and "preventing" diseases through collective "consultation"; For those questions that are close and easy to make mistakes, contrast exercises are organized to overcome the negative effect of thinking set, To cultivate students' ability of comparison and identification.
I usually design the exercises for students in this way: judge right and wrong → find out the mistakes → analyze the causes of mistakes → correct → summarize the methods of preventing the same kind of mistakes; You can also do comprehensive exercises; All kinds of wrong questions can be printed on the homework paper and sent to students for correction in class, or students can take out their own homework book and wrong question book and re analyze and revise the wrong questions in their homework.
in a word, the cultivation of students' computing ability should be carried out in the whole process of primary school mathematics teaching, which not only strengthens the training of students' basic skills, but also improves the teaching efficiency, At the same time, we should also pay attention to the targeted training of students. As long as we carefully study, constantly summarize and improve our work, and seriously excavate the ability factors in the calculation problems, students' calculation ability will be improved
5. Step
1
it is important to practice mental arithmetic
when children begin to learn mathematics, they may need to use some items to practice mathematics. However, if children have mastered mathematical calculation, they should not always rely on the method of putting things or counting fingers, but form a good habit of mental calculation
2
help children lay a good foundation
learning mathematics can't be accomplished overnight, but it's a long process. Therefore, we should lay a good foundation in order to be more solid in the future study. If we learn the foundation well, the problems behind will naturally come into being
3
remember the basic formula
the calculation ability of primary school students needs regular training, so that children can be familiar with and master the addition and subtraction methods within 20, including carry addition and abdication subtraction, in order to improve their oral calculation ability
4
adapt to the ecation mode
at present, the ecation mode in our country is teacher teaching and student learning, which is often indoctrination teaching. Parents should adapt to this situation and do not show inapplicability in front of children, so as to avoid children's aversion to learning
5
it's good to teach in fun
parents can teach their children mathematical calculation methods in normal games, such as playing cards and flying chess, so that their children can calculate relatively small numbers. After a long time, they will be proficient and their ability will be improved
6
learning is mainly encouraged
after all, learning will not be completed overnight, and it is a long process. Therefore, parents must encourage their children more. As long as they make progress, they should adopt the method of encouragement, and do not undermine their self-confidence
7
daily more guidance
learning also cares about the usual accumulation, so when we usually lead children to do things, we can focus on adding some mathematical content, such as counting money and shopping, so that children can actively participate and become more sensitive to numbers.
1
it is important to practice mental arithmetic
when children begin to learn mathematics, they may need to use some items to practice mathematics. However, if children have mastered mathematical calculation, they should not always rely on the method of putting things or counting fingers, but form a good habit of mental calculation
2
help children lay a good foundation
learning mathematics can't be accomplished overnight, but it's a long process. Therefore, we should lay a good foundation in order to be more solid in the future study. If we learn the foundation well, the problems behind will naturally come into being
3
remember the basic formula
the calculation ability of primary school students needs regular training, so that children can be familiar with and master the addition and subtraction methods within 20, including carry addition and abdication subtraction, in order to improve their oral calculation ability
4
adapt to the ecation mode
at present, the ecation mode in our country is teacher teaching and student learning, which is often indoctrination teaching. Parents should adapt to this situation and do not show inapplicability in front of children, so as to avoid children's aversion to learning
5
it's good to teach in fun
parents can teach their children mathematical calculation methods in normal games, such as playing cards and flying chess, so that their children can calculate relatively small numbers. After a long time, they will be proficient and their ability will be improved
6
learning is mainly encouraged
after all, learning will not be completed overnight, and it is a long process. Therefore, parents must encourage their children more. As long as they make progress, they should adopt the method of encouragement, and do not undermine their self-confidence
7
daily more guidance
learning also cares about the usual accumulation, so when we usually lead children to do things, we can focus on adding some mathematical content, such as counting money and shopping, so that children can actively participate and become more sensitive to numbers.
6. 1. Unicom's 4G network is a al 4G system, namely tdd-lte and fdd-lte (tdd-lte band: B41, 2600mhz, fdd-lte band: b31800mhz)
2. To use Unicom 4G, the following conditions must be met at the same time before LTE (4G) network function can be used. ① Unicom number needs to open 4G Internet access function and use USIM card; ② Mobile terminal needs to support Unicom 4G network; ③ It needs to be used in the area covered by Unicom's 4G network
3. Unicom 4G is automatically downward compatible with 3G. If there is no 4G network in its location, it will automatically switch to 3G network; Unicom 3G is automatically downward compatible with 2G, if there is no 3G signal or 3G signal is unstable, it will automatically switch to 2G.
4. For mobile phone system support, please check the mobile phone manual or contact the mobile phone manufacturer.
2. To use Unicom 4G, the following conditions must be met at the same time before LTE (4G) network function can be used. ① Unicom number needs to open 4G Internet access function and use USIM card; ② Mobile terminal needs to support Unicom 4G network; ③ It needs to be used in the area covered by Unicom's 4G network
3. Unicom 4G is automatically downward compatible with 3G. If there is no 4G network in its location, it will automatically switch to 3G network; Unicom 3G is automatically downward compatible with 2G, if there is no 3G signal or 3G signal is unstable, it will automatically switch to 2G.
4. For mobile phone system support, please check the mobile phone manual or contact the mobile phone manufacturer.
7. No, because there is no yunso ROM released on the Internet. Now we all want to turn tmall's box into an Android system. Do you still want to use it?? Alicloud system will delete the software installed by users. No more live.
8. In primary school mathematics teaching, calculation, as one of the important teaching contents, runs through the main line of primary school mathematics. It is an important basis for students to learn a lot of mathematical knowledge, and also one of the life skills that students must master in their future life and study. Therefore, we should attach great importance to the cultivation of computational ability. It is not only closely related to the basic knowledge of mathematics, but also interacts and promotes with the training of students' thinking and non intelligence factors. So, how to improve students' computing ability< Some students have not developed a good habit of living since childhood, and they do not have a good habit of learning when they move to study after school. They either read wrong numbers or write wrong numbers when they calculate; Either the wrong number or omit the symbol; Or addition forgets carry, subtraction forgets abdication, addition is done as subtraction, multiplication is taken as division, and decimal point forgets or wrong one place; Sometimes there are even some incomprehensible mistakes
2. They don't have a good grasp of the concept of calculation rules or operation order
some students also despise the learning of calculation problems, and often only pay attention to the results (calculation method), rather than the process of the results. As a result, students can't understand the calculation rules or operation order and principle very well, and they just memorize the calculation methods by rote, so they often make more mistakes in calculation. For example: in addition and subtraction operations, we often forget the borrowed number or the incoming number; in division with zero at the end of quotient, we often lose zero; in decimal multiplication, we often forget the decimal point of the proct on the point; in four mixed operations, we must pay attention to the algorithm, intermediate result, operation method, carry and retreat processing at the same time. Another example: 1.25 ×( 80+4)=1.25 × 80 + 4 = 100 + 4 = 104. The reason for the mistake is that when I studied the law of distribution by multiplication, I didn't understand 1.25 ×( 80 + 4) the meaning of this question is to find 84 1.25, you can first find 80 1.25, plus 4 1.25, a total of 84 1.25, naturally there will be no such error
3. The influence of thinking set
the negative effect of thinking set is mainly manifested in the use of habitual methods to solve completely different problems, resulting in errors. For example: 7.68-2.75 + 1.25 = 7.68-4 = 2.68 the reason for the error is that students are easy to be disturbed by the stimulation of familiar parts, which leads to errors. Another example: 4.9 + 0.1-4.9 + 0.1 = 5-5 = 0.24 × 5 = 100 and other errors are mainly caused by students' wrong thinking set
3. The role of non intelligence factors
non intelligence factors are also important reasons for students' calculation errors. Students are not interested in the importance of learning and the necessity of correctness. They only solve problems to cope with the teacher's examination, and they do not strive for accurate emotional tendency. They are absent-minded and perfunctory, resulting in errors. The second is the lack of patience. When calculating, students hope to work out the results soon. In the case of fear of difficulty and complexity and lack of patience, errors often occur< Second, the teaching strategy of cultivating computing ability
the cultivation of computing ability is a systematic project involving many aspects of teaching content, which not only enables students to master the mathematical concepts and knowledge related to computing, but also transforms knowledge into skills and skills through targeted, multi-level, multi-directional and multi form exercises. In order to effectively improve the calculation ability, we must follow the cognitive law of primary school students, adopt appropriate teaching strategies, so that students' understanding and mastery of mathematical knowledge and the formation of calculation ability can be developed simultaneously, so as to achieve the best teaching effect< (1) calculation law
calculation law refers to the general rules that must be followed in calculation, which promotes the calculation process to be programmed and regularized, and ensures the accuracy of calculation. The mastery of calculation rules is the guarantee of calculation accuracy
(2) operation order
operation order is a rule of operation order in the process of four mixed operations. The same level operations are calculated from left to right; There are two-level operations, the second level operation is calculated first, and then the first level operation is calculated; If there are brackets, we should calculate the ones inside the brackets first, and then the ones outside the brackets according to the order of parentheses. Mastering the operation order is the key to the four mixed operations
ring the teaching of four operations, a teacher encountered a problem. Although he marked the order of operations when the students began to contact the four operations according to the instructions in the teacher's book, some students still did not master the four operations well. One day, he wrote the word "respect for the elderly and love for the young" on the blackboard. He said: "respect for the elderly is placed in the front. First there is respect for the elderly, then there is love for the young. Our relatives have grandparents, parents, brothers and sisters. We should first think of giving things to grandparents, then our parents, and finally our brothers and sisters. In the family of arithmetic symbols, brackets are grandparents. We need to calculate brackets first, while multiplication and division are mom and dad. Our second step is to calculate multiplication and division, and finally we are brothers and sisters, that is, addition and subtraction. We say, we say, arithmetic symbols are family, who are grandparents, who are mom and Dad, who are brothers and sisters. " Next, he asked the children to retell their corresponding relationship several times in the way of a test, and then practiced. Later, the situation shows that the effect of his method is very good, and there are basically no more children who make mistakes in the operation order
(3) operation law and operation property
operation law and operation property are the generalization of the objective law of calculation, which reflects the inevitability of certain change process of calculation under certain conditions. By using the operation law and operation property, the calculation can be simplified< In the teaching of calculation, some teachers think that there is no reason for calculation. As long as the students master the calculation method and "practice" repeatedly, they can achieve the correct and skilled requirements. As a result, although many students are able to calculate according to the calculation rules, the scope of knowledge transfer is extremely limited because of unclear calculation, and they are unable to adapt to various specific situations in the calculation. If we pay attention to the calculation principle in teaching, we can make students not only know the calculation method, but also know the calculation principle of the control method, and know both the nature and the reason, then the calculation teaching will become lively and colorful
(1) explain the calculation through the demonstration of teaching aids
for example, when the first grade mathematics students have a preliminary understanding of the nature of "exchanging the position and invariability of addends", let the students observe the teacher's demonstration first: 3 chalks in the left hand and 4 chalks in the right hand. How many chalks in total? The formula is 3 + 4 = 7, the formula is 4 + 3 = 7. Through the demonstration, we can intuitively and vividly explain: in the addition formula, the position and invariability of the exchange addend
(2) understand the calculation through learning tools
for example, when teaching carry addition within 20, when the teacher shows 9 + 2 =? Generally speaking, students can quickly get the sum of 11. However, the purpose of teaching 9 plus several is not only for students to correctly calculate the result, but also to reveal the calculation law of carry addition, so that students can master the thinking process of "make ten" method, and train students' language expression ability. The operation of learning aids should be carried out step by step under the guidance of teachers: the first step is to lay out two piles of sticks, one pile of 9 sticks and the other pile of 2 sticks; The second part: while thinking and operating, put out the calculation results; Part three: oral process while operating. Divide 2 into 1 and 1, 9 plus 1 will get 10, 10 plus 1 will get 11, so that students can have a preliminary understanding of "gather ten methods". Step 4: show the thinking process of oral operation on the formula. Through the teaching of 9-plus-a-few, students can initially master the "10-plus-a-way". When teaching 8-plus-a-way, 7-plus-a-way and 6-plus-a-way, students can apply the "10-plus-a-way" in a large range and realize the transfer of knowledge
(3) explain the calculation theory with practice
for example, when teaching the addition and subtraction method of decimals, with the help of the rate relationship of RMB unit yuan, Jiao and Fen that students are familiar with, explain the reason that the decimal point must be aligned, that is, only two numbers with the same counting unit can be added and subtracted
(4) show ideas and clarify the calculation principle
when teaching the calculation principle of four operations, we often use the formula in the dotted line and box to clarify the calculation principle.
2. They don't have a good grasp of the concept of calculation rules or operation order
some students also despise the learning of calculation problems, and often only pay attention to the results (calculation method), rather than the process of the results. As a result, students can't understand the calculation rules or operation order and principle very well, and they just memorize the calculation methods by rote, so they often make more mistakes in calculation. For example: in addition and subtraction operations, we often forget the borrowed number or the incoming number; in division with zero at the end of quotient, we often lose zero; in decimal multiplication, we often forget the decimal point of the proct on the point; in four mixed operations, we must pay attention to the algorithm, intermediate result, operation method, carry and retreat processing at the same time. Another example: 1.25 ×( 80+4)=1.25 × 80 + 4 = 100 + 4 = 104. The reason for the mistake is that when I studied the law of distribution by multiplication, I didn't understand 1.25 ×( 80 + 4) the meaning of this question is to find 84 1.25, you can first find 80 1.25, plus 4 1.25, a total of 84 1.25, naturally there will be no such error
3. The influence of thinking set
the negative effect of thinking set is mainly manifested in the use of habitual methods to solve completely different problems, resulting in errors. For example: 7.68-2.75 + 1.25 = 7.68-4 = 2.68 the reason for the error is that students are easy to be disturbed by the stimulation of familiar parts, which leads to errors. Another example: 4.9 + 0.1-4.9 + 0.1 = 5-5 = 0.24 × 5 = 100 and other errors are mainly caused by students' wrong thinking set
3. The role of non intelligence factors
non intelligence factors are also important reasons for students' calculation errors. Students are not interested in the importance of learning and the necessity of correctness. They only solve problems to cope with the teacher's examination, and they do not strive for accurate emotional tendency. They are absent-minded and perfunctory, resulting in errors. The second is the lack of patience. When calculating, students hope to work out the results soon. In the case of fear of difficulty and complexity and lack of patience, errors often occur< Second, the teaching strategy of cultivating computing ability
the cultivation of computing ability is a systematic project involving many aspects of teaching content, which not only enables students to master the mathematical concepts and knowledge related to computing, but also transforms knowledge into skills and skills through targeted, multi-level, multi-directional and multi form exercises. In order to effectively improve the calculation ability, we must follow the cognitive law of primary school students, adopt appropriate teaching strategies, so that students' understanding and mastery of mathematical knowledge and the formation of calculation ability can be developed simultaneously, so as to achieve the best teaching effect< (1) calculation law
calculation law refers to the general rules that must be followed in calculation, which promotes the calculation process to be programmed and regularized, and ensures the accuracy of calculation. The mastery of calculation rules is the guarantee of calculation accuracy
(2) operation order
operation order is a rule of operation order in the process of four mixed operations. The same level operations are calculated from left to right; There are two-level operations, the second level operation is calculated first, and then the first level operation is calculated; If there are brackets, we should calculate the ones inside the brackets first, and then the ones outside the brackets according to the order of parentheses. Mastering the operation order is the key to the four mixed operations
ring the teaching of four operations, a teacher encountered a problem. Although he marked the order of operations when the students began to contact the four operations according to the instructions in the teacher's book, some students still did not master the four operations well. One day, he wrote the word "respect for the elderly and love for the young" on the blackboard. He said: "respect for the elderly is placed in the front. First there is respect for the elderly, then there is love for the young. Our relatives have grandparents, parents, brothers and sisters. We should first think of giving things to grandparents, then our parents, and finally our brothers and sisters. In the family of arithmetic symbols, brackets are grandparents. We need to calculate brackets first, while multiplication and division are mom and dad. Our second step is to calculate multiplication and division, and finally we are brothers and sisters, that is, addition and subtraction. We say, we say, arithmetic symbols are family, who are grandparents, who are mom and Dad, who are brothers and sisters. " Next, he asked the children to retell their corresponding relationship several times in the way of a test, and then practiced. Later, the situation shows that the effect of his method is very good, and there are basically no more children who make mistakes in the operation order
(3) operation law and operation property
operation law and operation property are the generalization of the objective law of calculation, which reflects the inevitability of certain change process of calculation under certain conditions. By using the operation law and operation property, the calculation can be simplified< In the teaching of calculation, some teachers think that there is no reason for calculation. As long as the students master the calculation method and "practice" repeatedly, they can achieve the correct and skilled requirements. As a result, although many students are able to calculate according to the calculation rules, the scope of knowledge transfer is extremely limited because of unclear calculation, and they are unable to adapt to various specific situations in the calculation. If we pay attention to the calculation principle in teaching, we can make students not only know the calculation method, but also know the calculation principle of the control method, and know both the nature and the reason, then the calculation teaching will become lively and colorful
(1) explain the calculation through the demonstration of teaching aids
for example, when the first grade mathematics students have a preliminary understanding of the nature of "exchanging the position and invariability of addends", let the students observe the teacher's demonstration first: 3 chalks in the left hand and 4 chalks in the right hand. How many chalks in total? The formula is 3 + 4 = 7, the formula is 4 + 3 = 7. Through the demonstration, we can intuitively and vividly explain: in the addition formula, the position and invariability of the exchange addend
(2) understand the calculation through learning tools
for example, when teaching carry addition within 20, when the teacher shows 9 + 2 =? Generally speaking, students can quickly get the sum of 11. However, the purpose of teaching 9 plus several is not only for students to correctly calculate the result, but also to reveal the calculation law of carry addition, so that students can master the thinking process of "make ten" method, and train students' language expression ability. The operation of learning aids should be carried out step by step under the guidance of teachers: the first step is to lay out two piles of sticks, one pile of 9 sticks and the other pile of 2 sticks; The second part: while thinking and operating, put out the calculation results; Part three: oral process while operating. Divide 2 into 1 and 1, 9 plus 1 will get 10, 10 plus 1 will get 11, so that students can have a preliminary understanding of "gather ten methods". Step 4: show the thinking process of oral operation on the formula. Through the teaching of 9-plus-a-few, students can initially master the "10-plus-a-way". When teaching 8-plus-a-way, 7-plus-a-way and 6-plus-a-way, students can apply the "10-plus-a-way" in a large range and realize the transfer of knowledge
(3) explain the calculation theory with practice
for example, when teaching the addition and subtraction method of decimals, with the help of the rate relationship of RMB unit yuan, Jiao and Fen that students are familiar with, explain the reason that the decimal point must be aligned, that is, only two numbers with the same counting unit can be added and subtracted
(4) show ideas and clarify the calculation principle
when teaching the calculation principle of four operations, we often use the formula in the dotted line and box to clarify the calculation principle.
9. Hello, I'm glad to serve you
m10refers to the thread code, 5g6g refers to the thread tolerance code, s refers to the thread length code
the accuracy is 100%, thank you for your adoption.
m10refers to the thread code, 5g6g refers to the thread tolerance code, s refers to the thread length code
the accuracy is 100%, thank you for your adoption.
10. The tolerance of external thread of m10is 5g6g, s refers to the short screw length
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