Multiplicative distribution method is taught on the basis of students' study of additive commutative law, associative law, multiplicative commutative law and associative law. Multiplication and division is also a law that is difficult for students to understand and describe. Therefore, in the teaching design of this class, I combine some basic concepts of the new curriculum standard with the specific situation of the region, pay attention to the reality of students, and closely link mathematical knowledge with real life, so that students can learn knowledge through constant perception and experience.
"Mathematics Curriculum Standard" points out: "Students' mathematics learning content should be realistic, meaningful and challenging. Paulia, a math educator, once said: "The primary responsibility of math teachers is to develop students' problem-solving ability as much as possible." However, in our previous teaching, we often pay more attention to solving mathematical problems in books, and students are helpless once they encounter practical problems. So at the beginning, I designed an opening to compare who has stronger computing ability, which greatly stimulated students' desire to learn. Students quickly list two formulas in different ways as required, and can easily prove that the two formulas are equal. Then let the students observe this equation and see if they can find any rules. On this basis, I am not in a hurry to let students talk about the law, but continue to provide students with challenging research opportunities: "Please name some equations that conform to the law in your mind", continue to let students observe, think and guess, then communicate, analyze and discuss, understand the characteristics of the equations, verify their internal laws, and sum up the laws of multiplication and distribution. This not only cultivates students' guessing ability, but also cultivates students' ability to verify guessing. Through independent exploration, students discover, guess, question, comprehend, adjust, verify and improve, and their subjectivity is fully exerted.
At the same time, I also attach great importance to cooperation and multi-directional interaction. Advocating the dynamic generation of classroom teaching is an important concept of the new curriculum standard. In mathematics learning, each student's thinking mode, intelligence and activity level are different. Therefore, in order to make different students develop in mathematics learning, I base myself on the multi-directional interaction among students, teachers and students, especially through mutual inspiration and supplement among students, to cultivate their sense of cooperation and realize the active construction of "multiplication and division method". In such an open environment, students learn from each other, experience the formation process of guessing, verifying and summarizing knowledge together, and experience the happiness of success together. It not only cultivates students' problem consciousness, but also broadens their thinking, and students also take the initiative to learn.
Applying laws and solving practical problems is the purpose of mathematics learning. In the design of exercise questions, they are not isolated, but organically linked. From basic questions to variant questions, from general questions to comprehensive questions, there is a certain gradient and breadth. Make students gradually deepen their understanding, and on the basis of making clear the arithmetic, they can flexibly use what they have learned, and make simple calculations and expand exercises according to the characteristics of the topic. Students are required to apply multiplication and division not only in the forward direction, but also in the reverse direction. Through the practice of positive and negative application, students' understanding of multiplication and division is deepened. Judging from the feedback in class, students are very enthusiastic and can apply what they have learned. Through their own efforts and exchanges and cooperation with their classmates, students have reached a satisfactory level in the speed and accuracy of solving problems. Only in this way can we really improve students' computing ability.
There are some bright spots in this class, but there are also many problems: the enthusiasm of students to participate is not as high as expected. It may be related to my relative lack of motivational language. It is also possible that students in the current disciplines are not very interested. But students are not interested in the materials, and teachers should try to make students interested in the presented materials. In addition, when answering questions, individual students are not fluent and accurate enough. The description of the law of multiplication and distribution is a bit wordy and not firm and confident enough. In this regard, we need to strengthen training and improvement in the future.
As early as last semester and the first few units of this textbook, multiplication and division were infiltrated. Although it was not revealed at that time, the students had a preliminary perception from the meaning of multiplication and realized that it could make the calculation simple. Today's teaching is based on this. The first class in the morning was in my own class, and then I went to listen to a teacher's class in the second class. Now let me compare and tell you my feelings:
First of all, it is worth learning from Mr. Mu that the students' preview work is in place. Before class, the students have solved the third and fourth questions of "think and do". By solving the third question, students can find the circumference of a rectangle in two ways, which not only consolidates the old knowledge, but also promotes the original knowledge and further feels the multiplication and division method from the perspective of solving practical problems. The fourth question highlights that the multiplication and division method can make the calculation simple and reflect the application value through calculation and comparison. There is no such preview before class, so the class time is rather hasty.
Secondly, after the students solved the problem of the example, I also asked the students to ask the problem of subtraction. The purpose of doing this is to make students feel that it is also suitable for this type of problem (a-b) × c = a× b-a× c, which not only expands students' knowledge, but also paves the way for learning simple operations tomorrow.
Finally, I think that when guiding students to observe and compare the relationship and differences between 65×5+45×5 and (65+45)×5, we can guide the observation from the perspective of numbers and operational symbols. After the students come to the conclusion, they have actually perceived the characteristics of the formula, and then let them create the same type of equation in their own way, which can be numbers, letters, graphics and so on. Thankfully, students can use various methods.
The disadvantage is that it is difficult for students to express the meaning of multiplication table in their own language. In group communication, some collaborators still play the role of bystanders, which requires the scientific guidance of teachers.
Multiplication table is an abstract concept course. Teachers can provide students with a variety of inquiry methods according to the characteristics of teaching content to stimulate students' autonomous consciousness.
The specific design is as follows: First, create a supermarket scene in Le Jia to stimulate students' enthusiasm for learning. By buying "3 sets of sportswear, each coat is 2 1 yuan, and each pair of pants is 10 yuan, how much does it cost?" By enumerating two different formulas, they can really realize that these two different formulas have equal relations. This is the first step: obtain information for further research through materials. (Although the information obtained is very simple, there are only a few groups of formulas with equal relations, but they are all obtained by the students themselves through activities, and the students are very familiar and kind to them. Taking them as the objects of further research can arouse students' sense of participation. )
Step 2: Observe the formula and find the law. Ask the students to discuss the distribution law of perceptual multiplication and make a guess: are the two formulas that conform to this form equal? At this point, the teacher should not rush to tell the students the answer, but let the students give examples to verify. It not only cultivates students' guessing ability, but also cultivates students' ability to verify guessing.
Step 3: Use the law to solve practical problems. By solving practical problems, the multiplication and distribution law is further broadened. This stage is not only a stage for students to consolidate and expand their knowledge, but also a stage for absorbing internalized knowledge, and it is also an important stage for developing students' innovative thinking.