Good afternoon, teachers, model essay 1, simple calculation of excellent speeches:
I'm talking about the third unit "Algorithm and Simple Calculation" in the second volume of the fourth grade primary school published by People's Education Press. I will interpret the curriculum standards and textbooks from six aspects: requirements of curriculum standards, content structure and compilation characteristics, arrangement style, integration of knowledge and skills, teaching suggestions and evaluation suggestions:
The first aspect: curriculum standard requirements
1. Content standard: The content of number and algebra plays an important role in the mathematics curriculum in compulsory education. The new curriculum standard emphasizes that students should experience, feel and understand the meaning of numbers and operations through actual situations, understand the process of establishing numbers and their operation models, develop students' sense of numbers and symbols, and pay attention to cultivating students' consciousness and ability to solve simple practical problems by using numbers and operations.
2. The goal of this unit in the second phase is to require students to: ① explore and understand additive commutative law, associative law, multiplicative commutative law, associative law and distributive law on the basis of students' original knowledge and experience, and be able to use these operational laws to perform some simple operations; (2) The consciousness and ability to choose the right algorithm according to the specific situation, and develop the flexibility of thinking; ③ Feel the connection between mathematics and real life, and use what you have learned to solve simple practical problems. Really experience that "mathematics comes from life and life reflects mathematics".
The second aspect: content structure and writing characteristics.
In mathematics, after the definition of operation is given, the most important basic work is to study the nature of operation. Among the various properties of operation, the most basic one is usually called "algorithm". On the basis of students' intuitive understanding, this unit sums up the operation rules of addition and multiplication, and learns to make simple calculations by using the operation rules. Because students have been exposed to a large number of examples about these five operation rules in their previous mathematics study, especially the interchangeability and combinability of addition, subtraction, multiplication and division, these experiences constitute the cognitive basis for learning this unit of knowledge.
This unit is divided into three sections, and the content structure is as follows:
Therefore, the textbook of this unit has the following main characteristics in arrangement.
1. The knowledge about the operation law is relatively concentrated, which is beneficial to students to form a relatively complete cognitive structure.
It is convenient for students to understand the internal relations and differences between the knowledge by concentrating the knowledge about the operation rules in one unit and arranging it systematically, which is beneficial for students to build a relatively complete knowledge structure through systematic learning.
2. Abstractly summarize the operation rules from the realistic problem situation, which is convenient for students to understand and apply. A remarkable feature of this textbook is that it is no longer just to give some examples of numerical calculation, so that students can find the law through calculation, but to help students understand the realistic background of the operation law by combining familiar problem situations. For example, the law of addition operation, the textbook arranged the scene of Uncle Li's cycling trip; The law of multiplication arranges the problem situation of students planting trees. This is convenient for students to rely on the existing knowledge and experience, analyze and compare different problem-solving methods, and get the operation law. At the same time, the textbook also arranges some practical problems in practice, so that students can further understand and understand the operation law by solving practical problems.
3. Paying attention to the flexible application of simple calculation in real life is conducive to improving students' ability to solve practical problems.
The third section of this unit changes the tendency of introducing algorithm skills into simple calculation, guides students to apply simple calculation to solve practical problems in real life, and pays attention to the diversification of problem-solving strategies. This will promote the development of students' thinking flexibility and improve their ability to analyze and solve problems.
The third aspect: arrangement style.
Combining the characteristics of mathematics itself, this unit emphasizes starting from students' existing life experience, and its basic model is: problem situation-exploring new knowledge-summing up-application expansion.
I will take the first section of this unit "The Law of Addition" as an example to talk about the layout style of this unit: the theme map records the itinerary in the trip. Considering that the students are not familiar with the recording instrument on the bicycle, they drew an enlarged picture of the surface of the instrument and asked the elf to make a suggestive introduction. Example 1 Put forward the problem to be solved on the basis of the topic map. Then, observe what the equation 40+56 = 56+40 explains, so that students can actively explore and summarize the laws in problem-solving activities and cultivate their general reasoning ability. Students can answer and communicate by themselves in the teaching process; Ask the students to express additive commutative law in their favorite way.
The fourth aspect: the integration of knowledge and skills
Horizontal integration of knowledge and skills
The textbook of this unit first creates a problem situation close to students' life, creating a happy and relaxed life-oriented learning situation for students, so that students can actively participate in mathematics activities, find problems, ask questions and solve problems. Close to students' life, make mathematics materials full of realism and stimulate students' desire to learn. For example, when learning additive commutative law, observe what the equation 40+56 = 56+40 explains, so that students can actively explore and summarize the laws in problem-solving activities and cultivate their general reasoning ability. On the basis of students' knowledge of additive commutative law, they should switch to the law of additive combination and master simple calculation methods, so as to further develop the flexibility of students' thinking and improve their ability to solve practical problems. On the basis of knowledge of multiplicative commutative law, students switch to multiplicative associative law and multiplicative distributive law, and master simple calculation methods. For the simple calculation part, how to calculate more simply cannot be generalized, but students are required to look at the specific data characteristics and use appropriate methods to calculate.
(B) vertical integration of knowledge and skills
Arithmetic and the unit of simple calculation are the contents of number and algebra. 1-3 grade, the operation of numbers is mainly combined with specific situations to understand the significance of four integer operations; Proficient in oral calculation of addition and subtraction within 20, multiplication and division within tables, simple addition and subtraction within 100, and multiplication and division of one-digit and two-digit numbers; Can calculate the addition and subtraction of two digits and three digits, the multiplication of one digit and two digits and three digits, and the division of two digits and three digits and one digit; Knowing parentheses, you can perform simple integer elementary arithmetic; Experience the process of communicating your own algorithm with others and be able to express your own ideas; Make an estimate according to the specific situation. In the second phase, students are required to calculate three digits multiplied by two digits and three digits divided by two digits. Able to perform simple integer elementary operations; Explore and understand the operation rules and apply them to some simple operations. The five algorithms learned in this unit are not only applicable to the addition and multiplication of integers, but also to the addition and multiplication of decimals, fractions and percentages in the future. With the further expansion of the range of numbers, they are still valid in the addition and multiplication of real numbers and even complex numbers. Therefore, these five algorithms have an important position and function in mathematics, and are known as "the cornerstone of the building of mathematics". The former knowledge is the foundation, the latter is the extension and expansion of the former, and the ability of gradual content spirals up.
The fifth aspect: teaching suggestions
It is not difficult to understand the algorithm and use it for simple calculations. Most students can master it in one or two classes, but there are a lot of variant exercises in multiplication table teaching, which requires teachers to know the content and structure of the textbook in advance, estimate the possible situations of students in advance and deal with them in time. Therefore, in order to better complete the teaching task and guide students to better master this part of knowledge. Combined with the writing characteristics and teaching difficulties of this unit, in classroom teaching,
1. Make full use of students' existing perceptual knowledge to promote the transfer of learning.
For primary school students, the generalization of the algorithm is abstract. The teaching of this unit should focus on helping students to turn these scattered perceptual knowledge into rational knowledge. (Slide 16) For example, (40+20)×25 and 47×23+23×53, 102×45 and 38×99+38, which directly apply the algorithm, are two examples of deformation applications.18× 45-8.
2. Strengthen the connection between mathematics and the real world and promote the understanding and application of knowledge.
One of the most obvious features of this textbook is to pay attention to the realistic background of mathematics, which embodies the desire of mathematics teaching to return to society and life. Therefore, understanding this intention of the textbook, making good use of the textbook and relying on the realistic prototype of mathematical knowledge can mobilize students' life experience, help students understand the operation rules they have learned and construct personalized knowledge meaning. Furthermore, with the understanding of the meaning of knowledge, it is also beneficial to the application of the learned operation rules.
3. Pay attention to the spirit of mathematics curriculum reform with diversified and personalized algorithms, and cultivate students' ability to choose algorithms flexibly and reasonably.
For primary school students, the application of the algorithm is more flexible and requires higher mathematical ability, which is one aspect of the problem. On the other hand, the application of the algorithm also provides an excellent opportunity to cultivate and develop the flexibility of students' thinking. In teaching, we should pay attention to let students explore and try, and let students communicate and question. Accordingly, teachers should also play a leading role. When students explore, they should observe carefully, ponder over their ideas carefully, guide them according to the situation, inspire them appropriately, and lose no time. When students communicate, listen patiently, understand students' real thoughts and give necessary guidance.
Model essay on the excellent lecture of Simple Calculation 2. On the design concept
"Mathematics teaching activities must be based on students' cognitive development level and existing knowledge and experience. Teachers should stimulate students' enthusiasm for learning, provide students with opportunities to fully engage in mathematics activities, and help students truly understand and master basic mathematics knowledge and skills, ideas and methods in the process of exploring and solving problems independently. Students are the masters of mathematics learning, and teachers are the organizers, guides and collaborators of mathematics activities. " This is one of the basic concepts of mathematical activities proposed by the compulsory education mathematics curriculum standard.
Therefore, it is necessary to change the traditional situation that teachers always "talk" and students passively "listen", give students the initiative to learn, fully trust students and mobilize their enthusiasm for learning. I quoted the teaching idea of "guiding inquiry learning and promoting active development" in classroom teaching, and constructed the inquiry learning model of this class.
Second, talk about design ideas.
1, oral teaching material
Mathematics is not only an indispensable tool for people's life and labor, but also can improve people's reasoning ability and abstract ability by learning mathematics.
The simple calculation of continuous division is the content of unit 3 in the second volume of fourth grade mathematics, the standard experimental textbook of compulsory education curriculum. It is based on students' understanding and mastery of the five algorithms of addition and subtraction and the nature of subtraction, and further learning some simple operations about four integer operations. The textbook mainly focuses on the comparison of different solutions, so that students can know that a number can be divisible by the product of two numbers continuously.
The arrangement intention of teaching materials is mainly to guide students to choose reasonable and simple calculation methods flexibly according to the characteristics of operation and data through typical examples closely related to real life.
The biggest feature of the textbook is to organically combine the discussion of simple operation with the solution of practical problems, so as to integrate the diversification of problem-solving strategies with the diversification of calculation methods. This can not only make the life background of practical problems become the empirical support for students to understand simple calculation methods and their reasoning, but also promote the cultivation and simultaneous improvement of problem-solving ability and calculation ability.
2, said the teaching objectives:
Based on the above ideas, teaching materials and students' actual situation, I have designed the following teaching objectives:
Teaching objectives:
Knowledge and skills: enable students to master several commonly used algorithms to divide a number into two numbers continuously. According to the specific situation, the appropriate method is selected to make the calculation simple.
Process and method: Teaching and learning the simple operation of continuous division by exploring and discovering methods.
Emotional attitude and values: cultivating students' ability to choose algorithms reasonably.
Teaching emphasis: Understand and master the nature of division.
Teaching difficulty: choose a reasonable algorithm.
Third, talk about the teaching process
This lesson constructs the classroom teaching mode of inquiry learning, and constructs four teaching links: review, inquiry, practice and classroom summary.
(a): review
Organize students to review the operation rules and properties of simple calculation and integer addition, subtraction, multiplication and division. The purpose is to let students recall the laws and properties, feel the function brought by using them in simple calculation, and feel the fun of simple calculation. Knowledge and emotion paved the way for exploring the simple operation of division.
(2): The inquiry process is explained in the following link.
1. Create a situation to stimulate interest.
As the saying goes, "A good beginning is half the battle", and the state of students at the beginning of the class sets the tone for this class. I talk to reality: in spring, everything recovers and flowers are red and green; Spring is also a good season for planting trees. Look: March 12, Arbor Day is coming, and students are carrying out tree planting activities. Therefore, introducing students into real life can not only stimulate students' interest in solving problems with their own knowledge, but also help them feel the role of mathematical knowledge and subtly carry out greening education.
2. Explore and solve problems.
In order to make students truly become the main body of exploration, cooperation and communication, I organized activities closely related to the teaching content, so that students can explore and solve problems independently.
This can not only make the life background of practical problems become the empirical support for students to understand simple calculation methods and their reasoning, but also promote the cultivation and simultaneous improvement of problem-solving ability and calculation ability.
3. Explore and discover the law.
When students' problem-solving methods are diversified, this establishes a knowledge platform for learning the simple operation of division. Therefore, by using the elf problem, students can explore and discover several algorithms of division by summarizing the problem-solving methods in the analysis and comparison of different methods, so that the problem-solving methods and abilities can be integrated with the cultivation of calculation methods and abilities, and mutual understanding and mastery can be promoted.
4. Explore the application of the law.
In this link, in order to let students flexibly choose reasonable and simple calculation methods according to the characteristics of operation and data, so as to cultivate their ability in this respect, three small links are arranged.
Application conditions.
This part puts forward to think about two problems, that is, there are several algorithms for continuous division. What are they? So, what about a number divided by the product of two numbers? What are the conditions for using the nature of division operation? In this way, students can further understand the nature of continuous division and prepare for its application.
Preliminary application.
In this link, two kinds of exercises are arranged: filling in operation symbols and judging, which are given in consideration of students' practical problems and are used to further understand and master; Second, prevent some unnecessary mistakes in the later group inquiry; Third, build a bridge for students and establish an application model.
C, in-depth exploration and application:
Piaget, a psychologist, pointed out: "Logic is abstracted from the activity of the subject, and activity is the main way and carrier of children's discovery. Therefore, this course will use students' independent exploration and group cooperation to start learning, so that students can use their own experience in practical activities to discover and explore by themselves, thus forming the ability to choose appropriate methods according to specific conditions to make calculations simple.
Firstly, students are required to choose multiple-choice groups independently, explore in groups and communicate within groups; Then send representatives to communicate with the whole class; Finally, * * *, like summary, forms a unified understanding: when calculating division, it can be calculated from left to right according to four operation orders (one number is divided by two numbers continuously), and sometimes it is easier to rewrite it as "the product of one number divided by two numbers" according to the characteristics of numbers. When calculating "the product of one number divided by two numbers", you can first calculate what is in brackets according to the four operation orders. According to the characteristics of numbers, it is sometimes easier to rewrite it as "one number divided by two numbers continuously".
(3), a variety of exercises, consolidate and improve
The new curriculum points out that "practice is an important means for students to acquire knowledge, form skills and develop intelligence". Because students' attention and interest cannot be maintained for a long time. Therefore, I used scenes such as solving practical problems in life in the design form of exercise questions. This can improve the enthusiasm of practice in a relaxed and happy atmosphere. In the design of content, a certain gradient is also arranged, which is conducive to understanding and consolidating the knowledge learned, thus forming new skills and techniques.
(4), exchange evaluation, class summary.
Students gain new knowledge and experience, whether cognitive or emotional, through independent inquiry learning, and then make their efforts clear by exchanging feelings and experiences, views and opinions in evaluation activities.
Finally, I designed your harvest and feelings in this class and told your deskmate about your harvest and feelings. Through communication, students can summarize what they have learned, which plays the role of combing and summarizing, refining and sublimating, thus promoting the formation of a new knowledge structure.
Fourth, talk about classroom learning evaluation.
Open teaching must be supplemented by open evaluation and personality-inspired learning evaluation. In terms of time, adopt the whole process evaluation, pay close attention to students' learning situation at any time, grasp students' bright spots and give evaluation in time; Content, pay attention to the evaluation of students' learning process; Formally, students are also allowed to comment on each other, causing controversy.