The first lesson is the first volume of the fourth grade, written multiplication-three times two, brought by teacher Wu Xiaoli, the mentor of Mingde team.
The pen calculation of multiplying three digits by two digits is based on the students' mastery of the pen calculation methods of multiplying three digits by one digit and multiplying two digits by two digits. This lesson tries to let students experience the exploration process of multiplying three digits by two digits according to the knowledge and methods they have learned before, and master the written calculation method of multiplying three digits by two digits through independent attempt, exploration and communication.
Teacher Wu's class can fully arouse students' learning enthusiasm. According to the requirements of mathematics curriculum standards, students are the main body, and teaching is carried out in the form of independent inquiry and cooperative exchange.
? 1. Guide students to explore new knowledge by transferring old knowledge.
? At the beginning of the class, Mr. Wu introduced, refined and summarized the method by solving the total price of 12 sets of summer school uniforms with the unit price of 45 yuan, so that students could understand the transformation idea of mathematics, lay the foundation for students to explore new knowledge and pave the way for three-digit multiplication by two-digit multiplication.
2. Give students enough time for autonomous learning and communication space, so that students can truly become the masters of learning.
? In this link, Mr. Wu left a lot of time for students to think fully, so that students can review and migrate on the basis of existing knowledge, try independently, and use students' board calculation process and other forms. Understand the calculation theory of multiplying three digits by two digits, and master the calculation method of multiplying three digits by two digits. In teaching, Mr. Wu is good at asking questions, giving key guidance to the difficulties in teaching, cultivating students' observation ability, expanding students' thinking and improving students' estimation and calculation ability by inviting you to be a small judge. At the same time, students can deepen their understanding and application of knowledge. Summarize the writing method of multiplying three digits by two digits, so that students can experience the fun of learning mathematics in thinking.
In this lesson, Mr. Wu's teaching embodies the concept of "active thinking, hands-on practice, independent inquiry, cooperation and communication" in the new curriculum standard. Taking students as the main body, on the basis of students' existing knowledge, using the transformation idea of mathematics and through students' original knowledge, this paper summarizes the calculation method of multiplying three digits by two digits, which is more prominent and pays attention to cultivating students' knowledge transfer ability. Strive to create a lively classroom atmosphere for students and form effective learning activities.
? The second class is the first volume of grade six, "A Number Divided by a Score", which was brought by teacher Fu Zhanhua, the team tutor of Xincheng.
? Some people say that the role of teachers is "transformation"-turning difficult problems into problems acceptable to students, which is a basic skill of teachers. Geometrical intuition mainly refers to describing and analyzing problems with graphics. With the help of geometric intuition, complex mathematical problems can be made concise and vivid, which is helpful to explore the thinking of solving problems and predict the results, and plays an important role in the whole mathematical learning process.
The understanding of dividing a number by a fraction has always been a difficult point in primary school computing teaching. Many teachers have come up with many good ways to break through this difficulty, such as drawing and origami. With the help of geometric intuition, Mr. Fu made the following teaching attempts and received good teaching results.
At the beginning of class, divide the moon cakes into two halves and look at the pictures. With the help of area and line segment model, let students understand how to divide a number by a few, that is, what is a fraction of this number.
Fu's process of exploring new knowledge is divided into five steps: the first step is to deduce the division formula to solve the problem according to the learned quantitative relationship class; In the second step, the application problem of division is transformed into a problem solved by continuous multiplication through drawing analysis. Thirdly, based on the fact that the division formula and the multiplication formula solve the same problem, the equivalence relationship between them is established. Step 4, multiply the last two numbers by the multiplicative associative law to get the reciprocal of the divisor, and realize the transformation that "dividing by a fraction is equal to multiplying the reciprocal of this fraction"; Step 5: Students conduct incomplete induction, "discovery" and summarize the calculation rules (rules) according to the analogy and verification of the examples in the class. Why to convert division into multiplication and multiply reciprocal is the choice of mathematics, because simplicity is the value orientation of mathematics and the eternal pursuit of mathematics.
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? The third class is the third grade "multiplication by writing" taught by teacher Zhang Meichun, a team tutor in Chengbei.
Teacher Zhang lets students discover and ask questions independently and try to calculate independently. In feedback, the calculation process is closely combined with the bar chart, and the reasoning and algorithm are communicated to break through the teaching difficulties. Finally, there are layered exercises.
When explaining the example 12×3, Mr. Zhang first asked the students to explore independently, and then let them get different calculation methods through communication, some with addition, some with oral calculation and some with vertical calculation. Especially for vertical calculation, there are similarities and differences in writing formats. Teacher Zhang didn't immediately tell the children which was easier, but asked the students to get the best written calculation method through observation and comparison. At the same time, by explaining the order and writing position of multiplication, students can master the correct writing format of multiplication and know the meaning of each step.
The children's active thinking and active speech infect every teacher in class, which makes us admire the teacher's cultivation of children's ability to observe, discover, use their brains and express orally.
Three math groups discussed in groups, and the teachers actively participated and expressed their opinions. The atmosphere of on-site learning and communication is strong. The teachers analyzed, compared and exchanged these three lessons, and put forward many valuable opinions.
? The three tutors give lectures from six perspectives: curriculum standards, teaching materials, students, teaching methods, training and process.
An excellent seminar is inseparable from the hard work of the teachers behind it. During the period, leaders and colleagues also gave them a lot of valuable opinions from the initial design teaching to the trial teaching, revision, re-education and finalization.
Entering the debate session, the teacher of Mingde Primary School and the director of Chengbei School, Li Yudong, enthusiastically expressed their opinions and feelings, and the wonderful debate speech was recognized and praised by the teachers present.
? Director Deng, the leader of the county teaching and research section, summed up today's three classes, not asking right or wrong, but sharing happiness. What do you usually teach? How to teach? What did you say?/Sorry? Why is it vertical? Why are there so many exercises? Why teach? Put forward your own in-depth thinking and explanation. Under the new curriculum standards, computing ability has become one of the core qualities of students. How to "combine reasoning with calculation", combine the thinking of arithmetic and algorithm, and refine the algorithm in order to get a higher starting point. At the same time, it also reminds teachers to look at problems from different angles and throw them back to students instead of rushing headlong into it and giving students time to think.
? Ouyang Zhuangping, the chief tutor of the studio, pointed out that the calculation rule of "a number divided by a fraction" is the most difficult point in the derivation of calculation rules in primary schools. How to arrange and teach this part of the content is more scientific, rigorous and concise, and it is more convenient for students to learn, understand and master by themselves? She made a comparative study and analysis of the arrangement of several mainstream versions at present, and shared some of her thoughts with you.
Finally, Ouyang put forward requirements and suggestions to the studio members, and made clear the content and direction of future teaching and research actions.
Calculation is the cornerstone of all mathematical activities, and it is also the main purpose of primary school mathematics teaching to cultivate primary school students' computing ability, but now students' computing ability is weakening, and the improvement of computing ability is the goal of all mathematics teachers. Today, the classroom presentation by the tutor of the famous teacher studio in the school district undoubtedly gives us some guidance. Learning, harvesting and improving computing power have a long way to go.