Second, the situation of "buying kites" was created, which stimulated students' interest in learning. When solving practical problems, it naturally leads to the learning content of decimals and integers, which makes students feel cordial and natural, and students explore new knowledge with strong interest.
Third, in the process of learning, I pay attention to students' independent thinking. For example, when solving practical problems, I ask students to think about communication solutions together. In the communication between teachers and students, students can fully express their views and calculation methods, so as to get many creative solutions. Then under the guidance of the teacher's inspiration, help students better understand the arithmetic and method of decimal multiplication of integers.
In short, this course pays more attention to students' learning process. In the study of thinking and communication, different students are given space to develop their thinking and promote their development.
Reflections on the Teaching of Decimal Multiplying Decimal System
There are several concerns about teaching this part of knowledge before class: 1. Can students understand why 1008 is divided by 100 in the example? 2. Can students find that the decimal places of the product are the sum of the decimal places of the factors? 3. Will the new lessons in the afternoon be worse than those in the morning? Will the students have a problem with it?
For example, ask a question, formulate it and estimate it. After putting forward the vertical calculation, the students immersed themselves in the calculation and toured around by themselves. Some students don't know how to calculate, so they gently remind them to calculate the formula into an integer. Some students face 1008. Although they put the decimal point between two zeros, they don't know why they are here. Tell me the estimated results; Most students know that because both factors are multiplied by 10, the product is multiplied by 100. To keep the original product unchanged, you need to divide the current product by 100. When several students talked about the whole calculation process, other students suddenly said, "Oh! I see! " So everything is connected. Try it. No problem. Let the students sum up the calculation rules themselves. Because in the teaching of multiplying decimal by integer, we attach great importance to let students summarize the calculation rules of multiplying decimal by integer, so here we only need to add "one * * *" to "how many decimal places are there in the factor". Finally, there are only five words on the blackboard: "calculate, look, count, point and correct". Remind students that they can check the calculation by estimating.
Today's example 2 still uses the example of the second class in the afternoon to talk about relevant mathematical information. After asking the first question, the students do their own vertical calculations. I don't need to explain at all, so I can say that when the decimal places of the product are not enough, we should use 0 to make up for it. The following "try it" is naturally smooth sailing.
Judging from the two-day homework, students' mistakes are not in methods, but in calculation, not carrying, misreading numbers, 7 × 7 = 46 and so on. Therefore, this part of my own judgment is "finished!" Example 3 will be given next Monday.
Doing nothing after class, I wrote Reflection on Teaching. The feeling is: "this part of knowledge is taught on the basis that students have mastered the calculation method of multiplying decimal by integer and the change of decimal size caused by moving decimal places." Although initially worried that students don't understand that the decimal places of the product are the sum of the decimal places of the factors. However, when I was teaching decimal multiplication, I paid great attention to let students sort out the calculation rules through calculation, so I found the attention points (simplify what can be simplified, and use 0 to make up when the decimal places of the product are not enough) and check the calculation through estimation. Therefore, in this part of the teaching, I can easily complete the teaching task.
Through the smooth teaching of these two examples, remind yourself to pay attention to the following points in teaching:
1. For the knowledge teaching of each unit, we must explain it in a down-to-earth manner, pay attention to the cultivation of students' ability, pay attention to the training of double basics, and let students pass every knowledge point. Don't stir-fry uncooked rice, so that your later teaching can proceed smoothly.
2. Students have different academic feelings, different acceptance abilities and different foundations. We should try to seize forty minutes in class and pay more attention to the knowledge of underachievers. Give them more opportunities to speak and act.
3. Pay attention to delving into the teaching materials before class, pay attention to the connection between the content to be taught and the teaching content in the early and late stages, clearly understand the students' learning situation, preset the places where students may have doubts, and improvise the problems existing in students. "
Reflections on the teaching of quadrature approximation
Paying attention to "creating situation" is a new bright spot of mathematics curriculum standard. It makes boring and abstract mathematical knowledge closer to students' social life and accords with students' cognitive experience. Enable students to acquire basic mathematics knowledge and skills in vivid and interesting situations and experience the value of learning mathematics. However, whether "creating situation" is a teacher's personal task or is completed by teachers and students together are two different ways in actual teaching. The following are some thoughts on the teaching of "product approximation".
First of all, it is necessary to avoid the situation carefully designed by a teacher when preparing lessons, and the situation that students are always "led by the nose" by the teacher when the teacher asks questions. In this way, students' subjective status and learning autonomy will be greatly reduced. It is necessary to naturally generate problem situations in the process of teacher-student interaction. The teaching of this lesson starts with the discussion of "what information should be considered when buying food" to understand students' real thoughts when solving this problem. Provide relevant information on the basis of fully respecting students' views, so that each student can become the creator of the situation. This lesson also creates a problem situation of "filling out invoices". Contacting the problem that everyone just solved, we asked, "Can you help the seller fill out an invoice?" Let students have the need to "fill in the invoice". Then guide students to try the process of filling in invoices themselves, and guide students to master the methods of filling in invoices in the process of filling in, so as to obtain "necessary mathematics" In this problem-solving situation, the main body of thinking is the students, and the teacher only gives targeted guidance according to the problems that students have at any time. Students are always active participants in problem situations. Creating situations is not a teacher's patent. Teachers should actively guide each student to participate in the process of situation design, so that the situation can really help students to learn independently and cooperate and communicate.
Secondly, we should avoid weakening students' dominant position, resulting in less information. The focus of the discussion should avoid staying on "the product should keep several decimal places" and guide students to further understand the application value of "the approximate value of the product". The teaching of this course makes students have doubts in practical application (write the invoice amount for the seller according to the calculation results), and try to solve them by themselves, so as to deepen their understanding and reach an understanding in communication (the money should be kept to two decimal places according to the actual situation), and then it can be used correctly in real life.
Finally, we should fully tap the materials from life, increase the amount of information, and strive to be targeted and open. The focus of the students' discussion finally stays on "which result is more reasonable". Therefore, in the process of discussing rationality, we fully realize the application value of "product approximation" in life, and strive to let every student learn "valuable mathematics". Example 5 After the teaching, arrange three levels of exercises to deepen understanding: First, give examples of teachers' purchases in life, some money should be kept in decimal points (shopping malls don't accept points), and some money should be kept in integers (free market bargaining, learning to cut off the tail), so that students can realize that they can keep it according to the actual situation; Secondly, through the practice of an application problem, let the students keep it many times according to the teacher's requirements, compare which value is the most accurate, and let the students know that the more numbers, the more accurate; Third, arrange an application problem whose calculation result is accurate to two decimal places, so that students can clearly judge the approximate value according to the actual situation. In the final consolidation exercise, students were asked to design a plan to buy three things according to the price lists of three shopping centers. Because students have to consider the price, quality, distance, time, reputation and other issues, so there are a variety of programs, which is an open question. Students not only have skills training, but also have the ability to solve practical problems.
"Multiply, multiply, add, multiply and subtract" is the content of the unit "decimal multiplication". There are many practical problems in life that need to be solved by multiplication and division. The textbook selects the familiar material "School Library Paving with Square Bricks" and designs "Paving with 100 tiles". Is that enough? 1 10? " Problem situation. By solving this problem, two formulas of decimal multiplication, multiplication and addition are given. Through these two different problem-solving ideas, students are guided to learn the multiplication, multiplication and addition operations of decimals, so that students can realize that the mixed operation order of decimals is the same as that of integers, and the mixed operation of decimals is also an important tool to solve practical problems in life. Before learning this lesson, students have already had the calculation experience of integer multiplication, multiplication, addition, addition, subtraction, multiplication and division, so it is not difficult to learn the content of this lesson. However, it should be noted that in teaching, students should feel the process of knowledge generation and development, and understand both decimal elementary arithmetic and integer elementary arithmetic to avoid blind knowledge transfer. So in this class, I try to do the following two things well: (1) Let students experience the process of knowledge formation. In modern education, knowledge is no longer the fundamental purpose of education, but a means to realize innovation. Therefore, students should feel the process of knowledge generation and development and cultivate their innovative consciousness in the teaching process. The knowledge learned in this lesson is not difficult and can be transferred completely. But in this way, the order of multiplication, multiplication, addition and addition and subtraction of decimals is equivalent to rote learning. Therefore, in this lesson, I use the situation provided by the textbook to inspire students to solve problems with different ideas, so that students can understand the order of multiplication, division, addition and subtraction of decimals in the process of solving problems, and at the same time realize that the order of multiplication, division, addition and subtraction of decimals is the same as that of integers. (2) Combine mathematics activities with students' life experience. In the process of teaching, I pay special attention to combining mathematics activities with students' life experience. For example, introducing floor tile activities that students are familiar with is convenient for students to start from their life experience, to understand, to help students solve problems with different ideas, and to help students identify with the laws to be understood in this class. When consolidating exercises, I pay special attention to applying the knowledge learned in this course to solving practical problems, so that students can feel the close connection between mathematics and life and stimulate their good feelings of learning mathematics well.
Reflections on the teaching of "multiplication, multiplication and addition, multiplication and subtraction"
"Multiply, multiply, add, multiply and subtract" is the content of the unit "decimal multiplication". There are many practical problems in life that need to be solved by multiplication and division. The textbook selects the familiar material "School Library Paving with Square Bricks" and designs "Paving with 100 tiles". Is that enough? 1 10? " Problem situation. By solving this problem, two formulas of decimal multiplication, multiplication and addition are given. Through these two different problem-solving ideas, students are guided to learn the multiplication, multiplication and addition operations of decimals, so that students can realize that the mixed operation order of decimals is the same as that of integers, and the mixed operation of decimals is also an important tool to solve practical problems in life. Before learning this lesson, students have already had the calculation experience of integer multiplication, multiplication, addition, addition, subtraction, multiplication and division, so it is not difficult to learn the content of this lesson. However, it should be noted that in teaching, students should feel the process of knowledge generation and development, and understand both decimal elementary arithmetic and integer elementary arithmetic to avoid blind knowledge transfer. So in this class, I try to do the following two things well: (1) Let students experience the process of knowledge formation. In modern education, knowledge is no longer the fundamental purpose of education, but a means to realize innovation. Therefore, students should feel the process of knowledge generation and development and cultivate their innovative consciousness in the teaching process. The knowledge learned in this lesson is not difficult and can be transferred completely. But in this way, the order of multiplication, multiplication, addition and addition and subtraction of decimals is equivalent to rote learning. Therefore, in this lesson, I use the situation provided by the textbook to inspire students to solve problems with different ideas, so that students can understand the order of multiplication, division, addition and subtraction of decimals in the process of solving problems, and at the same time realize that the order of multiplication, division, addition and subtraction of decimals is the same as that of integers. (2) Combine mathematics activities with students' life experience. In the process of teaching, I pay special attention to combining mathematics activities with students' life experience. For example, introducing floor tile activities that students are familiar with is convenient for students to start from their life experience, to understand, to help students solve problems with different ideas, and to help students identify with the laws to be understood in this class. When consolidating exercises, I pay special attention to applying the knowledge learned in this course to solving practical problems, so that students can feel the close connection between mathematics and life and stimulate their good feelings of learning mathematics well.
Reflections on the promotion of integer multiplication algorithm to decimal teaching
This lesson mainly makes students understand that the operation law of integer multiplication is also applicable to decimal multiplication. First show two sets of formulas:
0.7× 1.2 1.2×0.7
(0.8×0.5)×0.4 0.8×(0.5×0.4)
(2.4+3.6)×0.5 2.4×0.5+3.6×0.5
Let the students calculate in groups first, and then observe the characteristics of each group of formulas. In fact, these three groups of formulas use the exchange law, association law and distribution law of integer multiplication respectively, but these three groups of formulas are all fractional multiplication. Are they consistent? Let the students observe the calculation, find out the relationship between the two formulas in each group, and explore for themselves that "the commutative law, associative law and distributive law of integer multiplication are also applicable to fractional multiplication." Cultivate students' rational reasoning ability. In this link, the teacher's role is only to guide instructions, and never impose laws on students, but to let students calculate, observe and discover by themselves.
Learning knowledge and then solving problems with knowledge is the true meaning of mathematics learning. Now it is found that the laws of integer multiplication are also applicable to decimal multiplication. Applying these laws can make decimal calculation simple, and this step of teaching can stimulate students' desire to use new knowledge. Then display:
0.25×4.78×4 4.8×0.25
0.65×20 1 1.2×2.5+0.8×2.5
Let students experience the happiness of success in the process of simple calculation.
Disadvantages: only emphasize the law of operation, ignoring the ability of oral calculation. In practice, the reverse application of multiplication and distribution laws is not flexible enough.
In view of this phenomenon, I think it should be improved in practice class. Pay attention to students' reality, closely link mathematics knowledge with real life, and let students learn knowledge through constant perception and experience.