This book has eight chapters, which is the basic part of the whole junior high school stage. It is very important to learn the content of this section well.
The whole junior high school mathematics can be divided into three parts: space and graphics, number and algebra, and probability statistics. Among them, space and graphics include 1 basic geometric figures, number and algebra include 6 chapters, including 2 rational numbers, 3 rational number operations, 5 algebraic expressions and functions, 6 algebraic expressions addition and subtraction, 7 numerical estimates, 8 linear equations, and probability and statistics include 4 data acquisition and simple statistical charts.
Space and graphics
Chapter 1 Basic Geometry
The first chapter includes four sections: the graphic world around us,1.2 points, lines, surfaces, 1.3 line segments, rays and straight lines, and the measurement and comparison of 1.4 line segments.
The content of this chapter is that geometric figures, points, lines, surfaces and bodies are not only elements of geometric figures, but also basic geometric figures, while straight lines, rays and line segments are the basis for learning number axes, function images and various geometric figures. This chapter permeates some important mathematical ideas and methods, such as the combination of numbers and shapes, classified discussion, geometric transformation, etc., and begins the preliminary knowledge of graphic language and symbolic language, laying a good foundation for the subsequent study of related content.
Lines, rays and line segments are the simplest geometric figures, and more complex figures are composed of these simple figures, so this chapter takes them as the research objects. The idea put forward in this chapter is: know the line segments, rays and straight lines in real situations, know their differences and connections, learn their representation, drawing and comparison of line segment sizes, and get the nature that two points determine a straight line and the shortest line segment between two points through exploration.
Teaching focus:
Knowing the basic characteristics of common geometric bodies can correctly identify and simply classify these geometric bodies.
Breakthrough measures: Regarding the observation and analysis of various figures, we should not only start from perceptual knowledge, but also make full use of the intuition of examples and figures to understand the figures, and also understand the essence of these geometric bodies from individual examples and figures. Know points, lines and surfaces, and understand some simple properties and some basic figures of points and lines. Master the concepts, properties and expressions of line segments, lines and rays, as well as the expressions of words, figures and symbolic languages. Understand the distance between two points and the meaning of the midpoint of the line segment.
Teaching difficulties:
Making and designing patterns through unfolding, folding and making activities is the focus of this section. Understanding of geometric concepts and graphic properties and their expression in written language and symbolic language. The mutual transformation of line segment's literal language, graphic language and symbolic language.
Breakthrough measures:
Make full use of the previous chapter diagram and the previous chapter diagram. These situation diagrams show some main figures in this chapter (or this section), and guide students to cultivate their interest in mathematics in specific situations. Give full play to students' dominant position, leave enough space for students to participate in teaching, and guide students to actively participate, actively explore and cooperate to complete this lesson. Through life examples, let students know how to read and draw pictures, express the information in pictures in written language according to pictures, express related concepts and quantitative relations in symbolic language, and draw pictures correctly according to written language.
Numbers and algebra
Chapter II Rational Numbers
The second chapter includes three sections: 2. 1 positive and negative numbers around us, 2.2 number axis, 2.3 reciprocal and absolute value.
This chapter is the beginning of the third phase of "Number and Algebra" in nine-year compulsory education. In the first and second periods, students learned positive integers, zero and positive fractions (decimals), which are customarily called "arithmetic numbers". On this basis, this chapter introduces the concept of positive and negative numbers through the common quantities with opposite meanings in real life, thus expanding the scope of numbers to rational numbers; Through the concept of number axis, the corresponding relationship between rational number and points (rational points) on number axis is established. Through the concept of absolute value, the sign and absolute value of rational number are separated from each other, which lays the foundation for the establishment of rational number algorithm.
The concept of rational number is one of the most basic concepts in mathematics, which is widely used in real life and is an important basis for continuing to study algebra, equations, inequalities, functions and other mathematical contents and related disciplines. When the range of numbers is further supplemented, from rational numbers to real numbers and even complex numbers, many mathematical problems are still closely related to rational numbers.
Teaching emphasis: realize the importance of introducing negative numbers and the universality of rational numbers, and realize the close relationship between mathematical knowledge and real life.
1. Breakthrough measures: Through cooperative communication and independent inquiry, let students try to classify rational numbers and experience the mathematical thought in class. Rational numbers can be represented by points on the number axis.
Teaching difficulty: understanding the mathematical method of combining numbers and shapes.
Breakthrough measures: the establishment of the number axis and the mathematical idea of combining numbers and shapes established by the number axis are the key to learning this section.
Chapter III Operation of Rational Numbers
The third chapter includes five sections: 3. 1 addition and subtraction of rational numbers 3.2 multiplication and division of rational numbers 3.3 multiplication of rational numbers.
3.4 Mixed operation of rational numbers 3.5 Simple calculation with calculator
The content of this chapter is the accumulation of the content of Chapter 2. At the same time, the operation of rational numbers is the development and extension of the operation of positive integers and fractions. On the basis of the related operations learned in the first and second phases, there are negative numbers involved in the operations, so there is a sign problem. However, the arithmetic number correlation operation in the first and second phases is the basis of rational number operation, and rational number operation is the operational development of arithmetic numbers in the first and second phases. The operations of rational numbers, such as multiplication and division, are transformed into the operations of multiplication and division learned in the first and second phases when determining symbols. The operation of rational numbers is the most widely used basic operation and the important content of elementary mathematics, which lays the foundation for the operation of real numbers, algebraic expressions, fractions and quadratic roots to be studied in the future. Not only that, but also it is necessary to study other subjects. Therefore, it plays an important role in the study of mathematics and other subjects.
Teaching emphasis: master the laws of addition, multiplication and operation of rational numbers. The concept, expression and symbolic law of power are the key points.
Teaching difficulties: the addition of rational numbers, especially the law of adding two numbers with different symbols, and the omission of the plus sign in the mixed addition and subtraction formula of rational numbers are the difficulties in this chapter. Concepts such as power, floor and exponent are also difficult.
Breakthrough measures: create a real situation, explore the addition law of rational numbers with the help of number axis classification, grasp two key points: one is symbol, the other is absolute value, and break through this difficulty through the combination of numbers and shapes. Rational number multiplication is a new operation. The textbook introduces definitions and operational symbols through examples. Multiplication can be simplified as multiplication. The key is to let students understand the meaning and relationship of power, base and index.
Chapter 5: The preliminary relationship between algebra and function.
The fifth chapter includes five sections: 5. 1, numbers expressed by letters, 5.2 algebraic expressions, 5.3 numerical values, 5.4 constants and variables in life, and 5.5 functions.
On the basis of learning rational numbers and rational number operations, this chapter makes students familiar with examples and introduces letters to represent numbers, and then learns the basic knowledge of algebra and functions and introduces algebraic expressions, which is a leap in mathematics for students. Some algebras developed into functions, and began to study variables to realize the integration of algebras and functions.
Teaching emphases and difficulties:
Key points: use letters to represent numbers, and understand the meaning of letters representing numbers. According to the simple quantitative relation, the algebraic expressions are listed. You can express the meaning of algebra in natural language. Will find constants, variables, and express the relationship between variables with relational expressions.
Difficulties: Analyze the quantitative relationship of simple problems and express it with algebraic expressions. Column algebra; Expressing the meaning of algebra in natural language.
Ways to break through difficulties:
Carefully design questions, try to avoid false questions, and unconsciously teach students to express numbers and writing formats with letters in the dialogue situation with students, thus breaking through the key content. Through practice, students really realize that the value of letters in formulas containing letters has expanded to the range of rational numbers. According to specific problems, list algebraic formulas to break through the difficulties in this lesson.
Formulation → comparison → analysis → generalization → algebraic concept → column algebraic expression.
"Symbolic Language" → "Written Language"
① Solve the difficulties in three steps:
The formation process of the concept of creating situational solutions
Group cooperation and communication
Give practical meaning to the constructed algebraic expression.
Consolidate knowledge and explore problems through games.
② Arrange students for "mutual assistance and communication" in time.
Using rich materials provided by multimedia to assist teaching, fully arouse students' learning enthusiasm and break through teaching difficulties.
Use the materials and teaching materials provided to solve exercises and exercises, so that students can experience how to express the relationship between variables with relational expressions, thus solving teaching difficulties.
Chapter VI Addition and subtraction of algebraic expressions
The sixth chapter includes four sections: 6. 1 monomial and polynomial 6.2 similar terms 6.3 brackets removed 6.4 algebraic expressions added and subtracted.
This chapter is an extension of rational numbers, which are numbers expressed by letters and algebraic expressions. What you learn is not only the generalization and abstraction of rational numbers, but also the basis of learning algebraic expressions, the operation of fractions and roots, equations, inequalities, functions and other knowledge, and it is also an indispensable tool for learning physics, chemistry and other disciplines.
Addition and subtraction of algebraic expressions are actually two important identical variants of algebraic expressions: one is to merge similar terms; The other is to remove the brackets. The identity deformation of algebraic expression is the basis of symbolic operation in mathematics and a tool to solve equations. The algebra content of the subsequent study is almost related to this chapter. At the same time, this chapter is also training.
Teaching emphases and difficulties
Key points: the concept of single item, the coefficient and frequency of single item; Polynomials and the concepts of polynomial terms and degrees. Explore the characteristics of finding similar items and the law of merging similar items. The rule of removing brackets and its application.
Difficulties: determine the coefficient and degree of a single item accurately and quickly, and write the term and degree of a polynomial. There is a-sign before the brackets. When the brackets are deleted, the symbols of the items in brackets should be changed, and similar items and applications should be merged.
This chapter is the beginning of learning algebraic expressions. Knowledge is transformed from numbers to abstractions, which has a certain gap with students' cognitive basis and thinking ability, and it will be difficult to learn. Especially, it is easy to make mistakes when determining complex single coefficient and degree, polynomial term and degree. In order to break through the key points and resolve the difficulties, we should grasp the following two points in teaching:
(1) Strengthen intuition: provide students with enough perceptual materials to enrich their perceptual knowledge and help them understand concepts.
(2) Pay attention to analysis: When analyzing the structures of monomials and polynomials, with the help of variants and counterexamples, grasp the confusion of concepts and mistakes in judgment, and strengthen understanding.
Correctly understand the rules of removing brackets, and understand brackets and symbols before brackets as a whole. Practice Algebraic Expression Addition and Subtraction by Correctly Applying Similar Item Merging Rules
Chapter VII Numerical Estimation
Chapter 7 includes three sections: 7. 1 numerical estimation in life 7.2 application and adjustment of divisor and significant number 7.3 estimation.
In the new curriculum standard, "estimation" appears in many places, and it is clearly put forward that "pay attention to verbal calculation, strengthen estimation and encourage algorithm diversification"; It shows that the new curriculum attaches great importance to estimation. Because in people's daily life, estimation is often used much more than accurate calculation. Therefore, we should pay attention to the cultivation of estimation consciousness and estimation ability. Estimation plays a very extensive role in daily life and mathematics learning. It is of great significance to cultivate students' estimation habits, improve their estimation ability, make students have a good sense of numbers and improve their mathematical literacy.
Key points: master the estimation method initially and use estimation to solve practical problems. Understand the accuracy and significance of approximate number, experience the diversity of estimation methods, students learn estimation methods, experience the convenience of estimation under certain circumstances, and cultivate students' estimation consciousness.
Difficulties: According to the need to solve the problem, carry out numerical estimation strategically. Correctly grasp the precision of a divisor and the number of its significant digits. Students learn the method of estimation.
Chapter VIII One-variable Linear Equation
Chapter 8 includes five sections: 8. 1 equation and its solution, 8.2 linear equation, basic properties of 8.3 equation, solution of 8.4 linear equation and application of 8.5 linear equation.
Equations and equations are one of the main contents of Number and Algebra in junior middle school. One-dimensional linear equation is the simplest and most basic algebraic equation. It is not only widely used in practice, but also the basis for learning binary linear equations, univariate quadratic equations, fractional equations and other subsequent contents. Some concepts related to linear equations with one variable, such as the solution of equations and the solution of equations, are also important concepts with * * * in algebraic equations. The nature of equality is an important basis for the deformation and solution of algebraic equations. Therefore, the content of this chapter plays an important role in both practice and further research. Solving practical problems with linear equations plays an irreplaceable role in cultivating students' equation thinking and modeling ability, developing students' sense of numbers and symbols, and improving students' analytical ability and problem-solving ability.
Key points, difficulties and key points:
The focus of learning:
Enable students to list the linear equation of one yuan according to the quantitative relationship in specific problems, master the basic method of solving the linear equation of one yuan, and use the linear equation of one yuan to solve practical problems.
Learning difficulties:
According to the meaning of the question, find the "equivalence relation" and make a linear equation to solve practical problems.
In order to list the difficulty of solving practical problems by linear equations, from the first section, the textbook is equipped with many practical problems that students are interested in and exist in their lives, as an effective starting point for understanding and learning knowledge, making necessary preparations for listing equations. When introducing the application of linear equation to solve practical problems, we analyze the quantitative relationship in the problem and establish equations to solve the problem. The key for students to fully understand how to use equations to solve problems is to find out the equivalence relation and understand the importance of equation modeling, which can not only break through the difficulties, but also educate students to attach importance to analysis and form good habits of thinking correctly and being good at thinking.
Probability and Statistics
Chapter 4 Data Collection and Simple Statistical Chart
The fourth chapter includes four sections: 4. 1 data collection method, 4.2 data arrangement, 4.3 simple statistical chart,
4.4 Transformation of Statistical Chart
This chapter is a further study of data collection and representation based on the preliminary understanding of statistics in the second period. It is the beginning of data collection, collation, representation and analysis in statistics. This chapter mainly studies the collection, arrangement and simple statistical charts of data, which is not only the basis for studying data analysis and application in the future, but also of great significance for cultivating and developing students' sense of numbers and statistics.
Focus: making fan-shaped statistical charts.
Difficulties: making fan-shaped statistical charts; Select the appropriate statistical chart according to the conditions.
Key breakthrough:
Students can express their opinions through reading and painting, communicate in groups, and reach knowledge in groups, so as to master knowledge points.
Solutions to difficulties:
Guide students to analyze what is the key to drawing, suit the remedy to the case for the whole class, and find a breakthrough to solve the problem.
Through students' hands-on operation, observation and induction, teachers guide students to summarize and explain the key to mutual transformation, and combine drawing to summarize the methods of mutual transformation. Deepen the understanding of knowledge by drawing and recognizing pictures.
Difficulty breakthrough: To master the respective characteristics and functions of the three statistical charts, you can choose the appropriate statistical chart to complete the topic, and focus on letting students master the drawing from the steps.