Reflection on the approximation of product

Part 1: Teaching Reflection on the Approximate Value of Product

First, starting from the real problem, let the students do mathematics in specific situations, and create realistic scenes in the teachings. How to deal with the problem of “small money behind the 'points'” By thinking about the approximation of the approximation, it is the need of real life, highlighting the "contact with the actual life to think about the problem", and enhance the students' awareness of applying while grasping the relevant knowledge of the approximation.
Second, it is to pay attention to the cooperation and communication of students. The teaching provides a lot of experience for students to express, listen, and present their own ideas. For example, how to deal with the “thousands” behind the “points” and discuss whether the playground area is approximate or accurate. The value indicates that which one is intercepted, and these post-communication discussions deepen the students' understanding of the approximation, enrich the mathematics knowledge that the students have mastered, and at the same time cultivate the students' sense of cooperation.
Third, it is creative use of equipment, such as the case of situationalization, after the second and third questions of the exercise to expand the mathematical content, so creative use of equipment, so that the content of the textbook is closer to the actual life, more able to reflect the mathematical value of life, while It is also conducive to improving students' mastery of knowledge.

Part 2: Teaching Reflection on the Approximate Value of Product

1. Naturally generate problem situations in the process of teacher-student interaction
This class teaches you know what animal's sense of smell is the most sensitive? So people often use dogs to help detectives and housekeeping. Then question why the dog's sense of smell is the most sensitive? Enable students to solve problems.
2. Always pay attention to the subject of thinking is the student
In this problem-solving situation, students are always active participants in the problem situation. I only do targeted guidance based on the problems that students have at any time. In the process of calculation, we focus on letting students think for themselves, first try to solve them themselves, and In addition, in the exchanges to deepen understanding and reach a consensus, the focus of the discussion has always been concerned with "the product should retain a few decimals", and then can be correctly applied to real life.
3. Experience the application value of "approximate value of product"
In the teaching, we fully explore the materials from the life and increase the amount of information. The focus of the students' discussion is finally on the "what kind of results are more reasonable", fully understand the applicability value of the "approximate value of the product" in life, and strive for each student. Learn "valuable mathematics." Through a practice of solving problems, students can make multiple reservations according to the teacher's request, and compare which value is the most accurate, so that the students can be clear, the more the number, the more accurate; the other calculation result is exactly the set problem that two decimals do not need to be retained. Let the students clearly determine the approximate value according to the actual situation.
The practice time in the teaching time is slightly tense, and there are still some questions in the real life, should you keep a few decimals? Which is more reasonable? More in line with life? Worth exploring further.

Part 3: Reflection on the approximation of product

Through the actual teaching of the approximation of the product of fractional multiplication, I deeply understand the coherence of mathematics knowledge. Because the students' acceptance ability deviation, that is, the mathematics foundation is too poor, it has never been seen in actual teaching. Difficulties, I only start from the basics, have the concept of rounding off the law, step by step training how to find the approximate number, through repeated guidance, some students have basically grasped the approximation of the product, but there are many students difficult to accept, a question I feel awkward, I will patiently coach, let them first calculate accurately, taste the fun of computing, and then inspire students to use the existing mathematical knowledge, boldly to find the approximation of the product. After repeated practice, most of the students have improved. In short, in order for students to correctly and quickly find the approximation of the product, students must first make clear the reason, and then through comparative training and repeated practice can really improve the students' ability to accept.

Part 4: Reflection on the approximation of product

Paying attention to “creating the situation” is a new highlight in the “Mathematics Curriculum Standards”. It makes boring, abstract mathematical knowledge closer to the student's social life and in line with the student's cognitive experience. Enable students to acquire basic mathematics knowledge and skills in a lively and interesting situation and experience the value of learning mathematics. However, “creating the situation” is the task of the individual teacher or the teacher and the student, which are two different practices in the actual teaching. Let's talk about some of our own thoughts on the teaching of "approximate value of products".
First of all, the situation should be avoided when the teacher prepares the class carefully, and the problem is avoided by the teacher, so that the student is always “leaved by the nose”. In this way, the subjective status of students and the autonomy of learning are greatly reduced. It is necessary to naturally generate problem situations in the process of teacher-student interaction. This lesson begins with a discussion of “what information should be considered when buying food” to understand the students’ real thoughts when solving this problem. Provide relevant information based on full respect for the students' views, so that each student becomes the creation of the situation. This lesson also created the problem situation of “filling in the invoice”. By contacting the questions that you just solved, “Do you want to fill out an invoice for the seller?”, so that students can create the “fill invoice”. Then guide the students to try to fill out the invoice process, and guide the students to master the method of filling in the invoice during the filling process, thus obtaining the "necessary mathematics". In this problem-solving situation, the main body of thinking is the students, and the teachers only provide targeted guidance based on the problems that students have at any time. Students are always active participants in problem situations. Creating a situation is not a teacher's patent. Teachers should actively guide each student to participate in the process of situational design, so that the situation really helps students to learn independently and cooperate with each other.
Secondly, the amount of information caused by weakening the subject status of students should be avoided. The focus of discussion should be avoided in the “several decimals should be reserved”, and students should be guided to further appreciate the applicability value of “approximate value of products”. This class teaches students to have doubts in the actual application, and try to solve them themselves, so as to deepen understanding and reach consensus in the communication, and then apply it to real life.
Finally, we must fully exploit the materials from the life, increase the amount of information, and strive to be targeted and have a strong openness. The focus of the student discussion was also finally on the "what kind of results are more reasonable." Therefore, in the process of discussing rationality, we fully appreciate the value of the approximation of the product in life, and strive to learn "valuable mathematics" for each student. After the teaching of Example 5, arrange three levels of practice to deepen understanding: First, give examples of things to buy in the teacher's life, some money retains a decimal, some money retains an integer, and the students realize that they can be based on actual conditions. Second, through a practice of applying questions, the students can make multiple reservations according to the teacher's request, and compare which value is the most accurate, so that the students can be clear, the more the number, the more accurate; third, the arrangement of a calculation result is exactly Two sets of decimals do not need to be retained, so that students can clearly determine the approximate value according to the actual situation. In the final consolidation exercise, combined with the actual life, according to the price list of the three shopping malls, students are allowed to design and purchase three kinds of things. Since students have to consider the price, quality, distance, time, reputation and other issues, various solutions have emerged. Is an open question. Students have both skills training and the ability to solve practical problems.

Part V: Reflection on the Approximation of Product

Students are no strangers to the knowledge of this lesson. However, the content of the "approximation of quadrature" is simple, but it is rather boring. I first introduce the "rounding" method through review.
In the following teaching, I always appear in the teaching activities as the organizers, guides and collaborators of mathematics learning, providing students with space and time for full exploration, paying more attention to allowing students to communicate with each other, inductive methods, and training. Their ability to think and express. In the design of the exercise, I noticed that the forms of the exercises are diverse, which not only consolidates the knowledge acquired in this lesson, but also cultivates the students' learning ability.
The shortcoming is that the individual students of the “≈” in the horizontal style will not write, and the words “about” are not used in the answer. The reason is that I didn't instruct the students to write the "≈" answer when they were just an example.