The new people's education edition uses letters to represent numbers. First, teaching material analysis
This is the first lesson of the fifth-grade textbook "Representing Numbers with Letters" published by People's Education Publishing House. It is abstract for primary school students to represent numbers by letters. In the process of students' thinking, the transition from concrete numbers and formulas composed of operational symbols to letters and formulas containing letters is a process from individual to general abstraction. In the past four years of study, students have been exposed to the understanding and operation of specific numbers. Although they have some life experience and have been exposed to letters, they don't understand the meaning of letters. Based on students' existing learning and life experience, let students go through the process of mathematization and form a mathematical model, so as to experience the fun of mathematics learning. We have some ideas about the design of this course:
The knowledge of "using letters to represent numbers" plays an extremely important role in future study.
"Using letters to represent numbers" is not only of great significance to later mathematics learning, but also widely used in life and practice. Is it permeated in the teaching of this class? Transformation? Thought, follow the principle of subjectivity, guide students to observe, compare and analyze through teaching, and summarize the law of using letters to represent numbers. Then teaching uses this to express common quantitative relations.
According to the requirements of the syllabus, I set the main goal of this class.
1. Let students understand the meaning of using letters to represent numbers in real situations, and initially master the method of using letters to represent numbers. They will use formulas containing letters to represent numbers. I realize that using letters to represent numbers has the advantages of simplicity, clarity and quickness.
2. In the process of exploring the quantitative relationship in real life, let students gradually establish the consciousness of expressing numbers with various symbols and improve their abstract thinking ability.
The teaching emphases and difficulties of this course
1, key point: To understand the meaning of using letters to represent numbers, we will use formulas containing letters to represent the relationship between quantities.
2. Difficulties: Understand the meaning of letters representing numbers.
The design intention of teaching method
1, create a life-like mathematical problem situation.
In the problem situation, fully tap the theme map situation presented in the textbook, and pay attention to guiding students to observe things and think about problems from the perspective of mathematics. By guessing how many frogs may be hidden in the water, students can introduce letters to represent numbers. The initial experience is that many numbers can be represented by letters.
2. Mobilize children's existing life learning experience and establish a mathematical model.
Although students have never studied algebra, children have some experience in representing numbers with letters and the ability to solve problems with quantitative relations, so that students can analyze and solve problems in familiar and favorite activities. In addition, it can be understood that one number can be directly represented by letters, and the other number can be represented by a formula containing letters, thus establishing a model of letter formula. Learn how to express quantities with formulas containing letters; Promote students to understand the significance and superiority of using letters and formulas containing letters to represent numbers. At the same time, students can learn to express the quantitative relationship of multiplication with letters and formulas, and to abbreviate multiplication formulas with letters. So as to naturally promote the transition of students from arithmetic thinking to algebraic thinking.
3. Create a new learning experience and understand life in a mathematical way.
Through a series of mathematical activities, the mathematical model is gradually constructed. At this time, we designed expansion exercises to let children understand the meaning of formulas with letters in specific situations. From formulas with only one letter to formulas with two letters, from simple quantity with only one step to quantitative relationship with two or three steps, children's cognition is gradually deepening.
Teaching process arrangement
(1) Before class, the speaker organizes students to talk, adjusts the classroom atmosphere, and gradually introduces new knowledge.
(B), the exploration of new knowledge
1. Teaching the algorithm with letters.
2. Teaching uses letters to express calculation formulas.
3. Teaching is calculated by letter formula.
4. Teaching summary.
5. Classroom exercises
6. Question: What did we learn in this class?
7. Teacher's summary
(3) Comprehensive application
The new people's education edition uses letters to indicate the number of evaluation drafts. 1. Be good at creating effective teaching situations and stimulating students' interest in learning.
The new curriculum standard points out that mathematics teaching should be closely linked with students' life situations, and based on students' experience and existing knowledge, create a situation conducive to students' independent learning and cooperative communication? . For example, Teacher Xie introduced the topic with the age relationship between students and himself, and deepened the topic with the nursery rhymes of frogs. This series of familiar life situations including mathematics deeply touched the students? Mathematicians are around us? . Deepen students' understanding of what they have learned, so as to awaken students' life experience, stimulate students' interest in learning, and mobilize students' enthusiasm and effectiveness in exploring new knowledge independently.
Second, be good at tapping students' potential and stimulating their thirst for knowledge.
In the introduction part of this lesson, Mr. Xie first uses a numerical formula to indicate the teacher's age. After teacher Xie's persuasion and continuous excavation, students appeared to use formulas containing letters, figures, Chinese characters and symbols. The whole process from shallow to deep, from easy to difficult, naturally comfortable. The potential of students is naturally and unconsciously tapped by Teacher Xie. The same is true for later exercises.
Third, be good at cultivating students' thinking ability and improving their problem-solving skills.
In the whole class, Mr. Xie respects students' metacognition, their existing life experience and their individual differences, step by step, so that students' thinking is activated again and again, and students have made a leap.
For example, the transition from number formula to letter formula makes students unconsciously accept new knowledge and understand the meaning of using letters to represent numbers.
For example, according to the students' thinking habits, the letter A is used to indicate the students' age, so what is the teacher's age? a+ 13？ Teacher Xie created the requirement that students use the letter B to indicate the teacher's age, so what is the student's age? b- 13？ Combine advantages and disadvantages to make students' thinking collide with sparks and experience the fun of learning mathematics.
For example, in practice? Two boxes of chalk are represented by 2x, which can represent what students are under the guidance of Teacher Xie, and 2x can represent area, volume, weight, unit price and so on. Good diffusion of students' thinking, so that students gradually understand? Use letters to represent numbers? Concise and highly versatile.
Be good at grasping teaching key points, breaking through teaching difficulties and improving the rigor of students' thinking.
For example, the age gap between teachers and students, the multiple relationship between the number of frogs and the number of eyes and legs, etc. Let students understand that letters can not only represent numbers, but also find the quantitative relationship between them, and complete the teaching focus of this lesson very comfortably.
Through the students' existing life experience and the record of showing the oldest person in the world, let the students have a preliminary perception? In specific problems, the range of numbers expressed by letters often has certain limitations? . So as to better improve students' comprehensive ability to solve problems, make students' thinking habits more detailed and easily break through the teaching difficulties of this course.
Fifth, pay attention to the effectiveness, scientificity and preciseness of teaching design.
Thank you, teacher, for the instructional design of this class. Guide, learn and practice? This combination creates good conditions for students' autonomous learning. For example, effective project introduction; Students' self-study and independent inquiry, indicating the age of students and teachers with letters; Clear thinking and active thinking exercises, etc. I believe that teachers have a keen eye, which is the same as my feeling in class, so I won't go into details here.
Pay attention to teaching details and highlight strict teaching style.
So-called? How are you? , small also; ? Festival? People, units or key points; ? Details? This is a very small point. For example, Teacher Xie couldn't bear to drop an arithmetic symbol in class, and the knowledge points were clearly explained, so the students naturally got it from their younger siblings: 2? a=2*a=2a
For example, a student accidentally dropped the word "only counting" when introducing that the number of legs of a frog is four times that of a frog (only counting), and Teacher Xie also reminded him.
Russian educator ushinski pointed out:? In education, everything should be based on the teacher's personality? . In the teaching details, we can feel the teacher's personality characteristics and personality charm. Teachers' mental outlook, academic attitude, etc. Will have a subtle influence on students. Teachers' personality is the most intangible and powerful education for students. After listening to this lesson, Teacher Xie's teaching charm deeply infected me. I believe teachers feel the same way!