The interview is conducted by lectures or lectures, and structured interview questions will appear in many areas after lectures. Then, the following is a trial analysis of Numbers with Letters that I arranged for you. Welcome to read and browse.

First of all, talk about textbooks.

"Using letters to represent numbers" is the teaching content of "One-dimensional Equation", the first volume of the fifth grade mathematics textbook of "Compulsory Education Curriculum Standards" published by People's Education Publishing House. This is the beginning for students to learn the basic knowledge of algebra, and it is also the basis for learning equations, inequalities, functions and other knowledge.

It is abstract for primary school students to represent numbers by letters. The numbers in students' minds are concrete and definite, while the numbers represented by letters are abstract and changeable, which is a leap in understanding. It is a long process for students to express numbers with numbers and letters, which requires a lot of activities and rich experience.

In the past, in teaching, we often didn't dig deep into the meaning and function of letters representing numbers, and students' experience was not enough. Curriculum standards clearly point out: let students experience and understand mathematics in real situations. Therefore, in this class, I emphasize that students should experience it repeatedly in different situations, and realize that the meaning and function of using letters to represent numbers is the core of teaching, with emphasis on experience and perception.

Teaching objectives:

(1) Create different situations to promote students to understand the meaning of numbers represented by letters, and to know the different value ranges of numbers represented by letters.

(2) Being able to exchange letters in specific situations.

(3) Infiltration interval thought.

(4) Feel the beauty of simplicity in mathematics.

Teaching emphasis: Understand the meaning of using letters to represent numbers.

Difficulties in teaching: I feel that letters are used to represent uncertain numbers, and I know the different value ranges of letters (a number, a part of a number or any number).

Second, oral teaching methods

? Where there is teaching, there must be law, and where there is no teaching, there must be law? Only with proper methods can it be effective. According to the characteristics of teaching content and students' thinking activities, I adopted the teaching method of combining teaching with practice. The exploration process follows: from concrete to abstract, from individual to general, and then from general to individual.

Third, students study law.

First of all, teachers create a good environment, guide students to start with favorite, known and familiar life content, and let students unconsciously establish letters in a specific environment. These letters are in life and around us. Then, through a series of activities, let students cooperate and explore independently, and further understand that letters can not only represent a specific number, but also represent a changing number. The range of numbers represented by the same letter in different situations is constantly changing. Then, through various connections, it is transformed into problem-solving strategies to explore the different abilities of students at different levels and cultivate students' ability to dig, communicate and solve problems.

Fourth, talk about teaching procedures:

The whole teaching process is arranged in five links.

Link 1: Understand the meaning of using letters to represent numbers, and know that letters represent different value ranges of numbers. This is the focus and difficulty of this lesson. The New Curriculum Standard points out that mathematics teaching is the teaching of mathematics activities and the process of interactive development between teachers and students. So in the first link, I preset two activities, one is different levels of experience.

Activity 1: Let students know that letters represent a definite number.

1, a lesson, courseware shows different pictures, so that students can know through observation that letters can be used not only to represent the names of things, but also to represent numbers, thus introducing new lessons.

2. An example of 1 is given. Through observation, it is found that these symbols and letters can be used to represent numbers. ■, ▲, ● and other symbols indicate that students have been exposed before, and letters indicate that numbers are new knowledge. The purpose of solving the example 1 is to realize once again that a certain number is represented by letters.

Activity 2: Promote students' perception of uncertain numbers represented by letters, and promote students' perception of different intervals of numbers represented by letters in specific situations.

Draw a square to list multiplication formulas with letters.

Show the courseware one by one:

After the students write the corresponding formula according to the number of squares placed, the teacher asks: A square like this can be kept. Can you use more formulas to express the number of sticks used to place different numbers of squares? Then let the students write down the formula, let the students experience the benefits of using letters to represent numbers, and then let the students try to summarize all the formulas with a formula, that is, a formula containing letters. Let the students know that letters can not only represent a specific number, but also represent a changing number.

Then, guide the students to observe and find that the number of squares is constantly changing, and the number of sticks is also constantly changing, but it is the same whether to put a square with four sticks or use sticks. The relationship that the number of squares is three times that of squares will never change. This is as the German mathematician Kepler said? Does mathematics study the unchangeable relationship under ever-changing circumstances? .

Finally, the teacher deliberately asked:? Answer? What numbers can be represented here? Can they be decimal? Can it be a score? The range of numbers represented by the same letter in different situations is constantly changing, which is the students' initial understanding. The teaching of this knowledge point aims to guide students to re-explore the relationship between numbers and quantities expressed by letters and formulas containing letters, and at the same time organically infiltrate the idea of functions and realize the necessity of expressing numbers by letters.

Link 2: Explore the calculation formula of using letters to represent related numbers, and promote students to understand that different intervals of letters represent numbers in abstract form.

First of all, the teacher asked: How to calculate the circumference of a square (answer, the teacher showed the formula for calculating the circumference)? How to calculate the area of a square (answer, the teacher shows the formula for calculating the area)

Then, the courseware shows the letter representation requirements of square perimeter and area formulas.

Then, according to these requirements, guide students to express these two formulas in letters. (student: blackboard: C=a? 4、S=a？ answer

This level of teaching aims to guide students to use letters to express the calculation formula of the learned graphics and re-experience the function of letters.

Link 3: shorthand method of teaching multiplication formula with letters.

1. Ask students to write down new knowledge, discoveries and problems that you think are important, and give feedback on their self-study.

Then, arrange exercises about applying shorthand rules:

The student answered c=a? 4、s=a？ Abbreviation formula of A (teacher's blackboard writing).

2. Integrate applications

Ask a question and answer a question in groups.

3. Use letters to represent the learned algorithms.

4. Calculate the perimeter and area of the square with the letter formula.

First, let the students discuss what conditions must be known in order to find the area or perimeter of a square. Then, let the group work together to measure the side length of the square, and then use the formula to find its area and perimeter. Objective To make students feel that letters can not only represent changing numbers, but also the range of numbers they represent is constantly changing. Students finish independently, with emphasis on writing format.

Link 4: class summary

Link 5: Extension and Extension

Courseware demonstration:

(1) Records of the earliest use of letters by humans.

(2) introduction? Father of algebra? Veda.

This link will penetrate into the mathematical culture in time, aiming to let students know the relevant knowledge of the history of mathematics, and at the same time be influenced by ideological education and emotion, so as to better promote the development of students.

Link 6: Swimming? Olympic maze? (Show the courseware one by one)

First of all, the distance from the entrance to the wisdom house, the cruise hall and the music bar is expressed by letters and formulas containing letters respectively. Ask the students to talk about why three distances should be represented by different letters, and then realize that different numbers should be represented by different letters in the same formula.

Then, come to the music bar. What happened in the music bar?

Use letters and expressions containing letters to represent the whole song? Count frogs? Children's songs (? Try it? 1)

Go to Fuwa Square again (true or false)

Finally go to the wisdom palace. There is a mural in the wisdom palace. Ask the students to talk about the connection between the picture above and 7a below. If you remove the seven volleyball balls above, what kind of picture can you change for him? Objective To let students know that many meaningful examples in life can be represented by 7a.

Einstein said: Interest is the best teacher. ? In view of the fact that using letters to represent numbers is abstract and boring, it is specially designed? Swimming in the Happy Garden? The purpose of situational series is to guide students to comprehensively use the knowledge and skills they have learned, improve their ability to solve problems, experience the fun of solving problems and stimulate their love for mathematics through vivid and diverse exercises.

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