The teaching of physical laws is the central link for students to master the theory of physical science and one of the cores of physical teaching.
Based on the author's years of physics teaching experience, this paper discusses how to do well the teaching of physics laws in middle school.
Keywords: teaching of physical laws
Physical laws reflect the mutual restriction between physical concepts and the inevitability of certain physical processes under certain conditions.
It is the most important content in the basic knowledge of physics in middle school and the hub of the physical knowledge structure system. Therefore, the teaching of physical laws is the central link for students to master the theory of physical science, and it is also one of the cores of physics teaching.
How can we do regular teaching well? According to my years of physics teaching experience, I want to talk about the following points:
First, create a physical environment for discovering problems and exploring laws.
Teachers lead students to learn the laws of physics, first of all, they need to guide students to find problems in the physical world.
Therefore, at the beginning of teaching, it is necessary to create a physical environment for students to easily find problems.
In the middle school stage, problems are found mainly through observation and experiments, from analyzing typical cases familiar with students' lives, and sometimes from analyzing students' existing knowledge.
On the other hand, the created physical environment should be conducive to guiding students to explore the law.
For example, to enable students to acquire perceptual knowledge and data necessary for exploring physical laws; Provide clues and basis for further thinking; Provide necessary knowledge preparation for studying problems and so on.
The created physical environment should also help to stimulate students' interest in learning and curiosity.
Second, guide students to explore the laws of physics
When students have certain needs and are actively prepared, teachers should use various appropriate methods such as experimental exploration and theoretical deduction to explain the formation process of concepts and laws to students and establish the connection between old and new knowledge.
For example, in the teaching of Newton's second law, let students explore the relationship between acceleration and force and between acceleration and mass through experiments, and draw the conclusion that acceleration is directly proportional to external force under certain mass and inversely proportional to mass under certain external force.
On this basis, teachers guide students to sum up the relationship among acceleration, external force and mass, and conclude Newton's second law.
In this way, students will have a clear process of establishing laws, and then they can deeply understand physical laws and understand their physical significance.
On the other hand, when presenting the contents of physical laws to students, we should not only be accurate, but also highlight some key words, give appropriate explanations, guide students to give enough attention and correct understanding, and compare them with other similar or confusing concepts and laws, establish analogy links, and deepen their understanding of physical laws.
Third, let students deeply understand the physical meaning of the law.
In regular teaching, students should be guided to deeply understand its physical meaning and avoid rote learning.
There are two main ways to express physical laws: one is written language, and the other is mathematical language, that is, formula.
The written expression of physical laws must be carried out on the basis of students' analysis and study of related problems and their understanding of their essence. Never "move out" or "fill in" students without any understanding or insufficient understanding, and then explain and explain word by word.
Only in this way can students really understand its meaning.
For example, Newton's first law, "All objects always keep a uniform linear motion or a static state when they are not acted by external forces." When understanding, we should pay attention to the fact that the law is the condition that "the object is not affected by external forces" and understand the meaning of the word "or".
"Or" doesn't mean that an object sometimes keeps moving in a straight line at a uniform speed, and sometimes it stays still, but that if the object is moving, it will keep moving in a straight line at a uniform speed; If it is stationary, it will remain stationary.
For the physical laws expressed in mathematical language, that is, formulas, students should understand the quantitative relationship between physical quantities expressed in formulas from a physical sense, rather than from a purely mathematical point of view.
For example, for the same point in the electric field, it cannot be said that the field strength E is directly proportional to the electric field force F and inversely proportional to the electric quantity Q, because the field strength E is determined by the electric field and the position of the point in the electric field.
Fourth, make students clear about the applicable conditions and scope of physical laws.
Physical laws are often established or derived under certain conditions and can only be used within a certain range. Beyond this range, the laws of physics will not hold, and sometimes even wrong conclusions will be drawn. This point is often easily overlooked by students. When they encounter specific problems, they misuse the laws of physics and draw wrong conclusions. Therefore, in the teaching of physical laws, students should be clear about the applicable conditions and scope of physical laws, and correctly use physical laws to study and solve problems.
For example, the law of conservation of momentum is based on the condition that the system under study is free from external force or the resultant force of external force is zero, which is a benchmark condition.
If the external force F or the resultant force F is not zero, the momentum of the system is not conserved, but there may be two situations: first, the internal force F of the interaction between objects in the system is much greater than the external force F (or F), and the momentum of the system can be regarded as conserved, and its conditions are approximate; Secondly, after selecting the rectangular coordinate system, the external forces that are not on the coordinate axis are decomposed orthogonally along the X axis and the Y axis respectively. If the resultant force of external force (including component) along a coordinate axis (such as X axis) is zero, the momentum of the system in this axis direction is conserved, which belongs to the conservation condition of component momentum.
The law of conservation of momentum is one of the basic laws universally applicable in nature, which is applicable to systems composed of two or more objects. It can not only solve the problem of low-speed motion, but also solve the problem of high-speed motion; It is not only applicable to macroscopic objects, but also to microscopic particles such as electrons, protons and neutrons.
In addition, the law of conservation of momentum is applicable regardless of the nature of the interaction.
Five, strengthen the application of physical laws to solve practical problems of training and guidance.
Physical laws come from physical phenomena and are applied to practical problems in turn. The purpose of studying the laws of physics is to be able to use the laws of physics to solve practical problems. At the same time, through the application, it can also test students' mastery of physical laws and deepen their understanding of physical laws.
In the conventional teaching, on the one hand, we should choose appropriate physical problems, train them in a planned and targeted way, from simple to complex, step by step and repeatedly, so that students can deepen and activate their understanding of physical laws, and gradually understand the ideas and methods of analyzing, handling and solving problems in combination with the discussion of practical problems; On the other hand, it is necessary to guide and train students to be good at learning physical laws in combination with practical problems in daily life, and often use the learned laws to scientifically explain and explain related phenomena. Through training, students can gradually learn logical reasoning and expression. For analyzing and solving practical problems by using physical laws, students should be gradually trained to use the ideas and methods of analyzing and solving problems, so that students can learn to use mathematics correctly to solve physical problems. Finally, it is pointed out that due to the complexity of physical laws, we must pay attention to the stages of law teaching, so that students' understanding of laws can be deepened and improved step by step.
Only in this way can we effectively guide students to master the laws of physics and cultivate their thinking ability.
refer to
1. People's Education Press Physics Room.
Physics syllabus for full-time senior middle schools in 2003
2. Tian Shikun, Hu Weiping. On physical thinking [M]. Nanning: Guangxi Education Press, 1996.438+067.
3. Nanchong Research on physics teaching in middle schools [M]. Beijing: Haichao Publishing House, 1993.09.
The college entrance examination is a major event related to thousands of families, and it is also the way for the country to select talents at present. Seriously study and study the Syllabus and Exam Instructions, review scientifically according to the teaching rules, collect and process information in time, and fully mobilize students' learning enthusiasm, which will certainly achieve good results.
Keywords organizational review ability of college entrance examination
In order to implement the college entrance examination review, make the review process more scientific and efficient, and help students improve their grades to the greatest extent, the following suggestions are put forward:
1. Strengthen the review of basic knowledge and strengthen students' in-depth understanding of concepts and laws.
In senior high school, the requirements for basic concepts and basic laws have always been the main content and key content of college entrance examination physics examination. It mainly examines the mastery of basic concepts, basic laws and basic methods on the basis of understanding, and requires a deep understanding of the internal relationship between concepts and laws. Many students have this performance: everyone knows the concept and definition, but it is wrong to use it. The performance on the test paper is mainly the low score rate of multiple-choice questions. These are all closely related to poor foundation and insufficient understanding of physical concepts and laws. In recent years, the physics test questions in college entrance examination papers all over the country also clearly show the characteristics of attaching importance to basic concepts and regular examination.
In this regard, in the review, students' five abilities should be strictly required in accordance with the physics syllabus and examination instructions, and at the same time, students should understand that understanding ability is the foundation. Only when understanding ability is improved can other abilities develop well, and the premise of understanding ability is solid basic knowledge, solid basic skills and standardized basic methods. Only by reviewing basic knowledge, skills and methods can we correctly, profoundly and thoroughly understand concepts and laws.
2. Strengthen students' abilities of calculation and reasoning, demonstration and expression, and comprehensive analysis.
The examination of college entrance examination physics questions runs through all kinds of questions. Through different questions and different situation settings, the logic and rigor of candidates' reasoning are investigated from different angles and levels. The expression of argumentative essays focuses on whether the reasoning process can be expressed accurately and concisely, so as to identify the candidates' expressive ability. It is necessary to overcome that students' thinking and reasoning process can not be strictly logical, and they do not pay attention to force analysis and motion process analysis, which brings blindness to solving problems; The physical process or law cannot be expressed in physical language, which makes the problem-solving process incomplete; Newton's law of motion, momentum and function are out of touch with each other and cannot be organically integrated, which makes the thinking and method of solving problems rigid and the correct rate low.
3. Improve students' ability to apply mathematical knowledge to solve physical problems.
Physics and mathematics are closely related, and mathematics provides a powerful tool for the development of physics. Almost all physical concepts and laws are described by mathematical formulas through quantitative methods. The ability to deal with physical problems with applied mathematics is also the ability that candidates who enter colleges and universities should have. Therefore, the college entrance examination physics questions have always focused on examining the ability of candidates to deal with physical problems with applied mathematics.
In recent years, the requirements of college entrance examination physics for mathematical ability have been obviously adjusted, mainly in avoiding complex mechanical operations as much as possible. To this end, on the one hand, we require students to have a certain number of exercises in their usual study and master the common mathematical laws and methods for solving physical problems. On this basis, students are guided to gradually form the basic idea of using mathematical tools to deal with physical problems, with the emphasis on strengthening teaching and refining, so that students can skillfully transform physical problems into mathematical problems. In addition, we should pay attention to the training of estimation questions, guide students to master approximate estimation method step by step, and quickly find out the order of magnitude of physical quantities during review. At the same time, students are encouraged not to use calculators or less, because many students are used to using calculators in their usual exercises, even for very simple addition and subtraction, which makes their mathematical operation ability poor.
4. Strengthen experimental review
Experiment is the foundation of physics, and experimental ability has always occupied a very important position in the college entrance examination of physics. Physics college entrance examination attempts to examine students' experimental ability in the form of written test.
In teaching, first, we should treat experimental teaching materials correctly. When reviewing experiments, we should not mechanically memorize the purpose, principle, equipment, steps, records and results of each experiment in the textbook, but guide students to understand the design ideas, scientific methods, standardized operating procedures and reasonable experimental steps of physical experiments in the textbook. The second is to arouse students' intentional attention to the experiment, provide more opportunities to use their hands and brains, and let them take the initiative to find and solve problems. Teachers deliberately change the experimental conditions and set questions, and encourage students to find ways to solve problems. Third, starting from cultivating students' experimental ability, through experimental measurement and planned practice activities, let them learn how to understand nature, discover natural laws, verify hypotheses and guesses, and cultivate their scientific thinking mode, scientific methods, practical operation skills and ability to solve practical problems. Fourth, encourage students to innovate boldly and realize that the methods provided by experimental textbooks are not static and rigid. We can make some reasonable changes to the experiments in textbooks, or supplement some imitative experiments and add some designed experiments to cultivate students' ability to solve new problems by using the knowledge and methods they have learned.
In order to make the preparation for the review go smoothly and strive to complete the tasks of the school, the following measures are put forward:
1. What's more important is to carefully study the college entrance examination syllabus, teaching syllabus and teaching materials, fully improve the role of "two programs and one book" in the college entrance examination, study the "two programs", and especially analyze the subtle differences between the college entrance examination syllabuses every year. At the same time, students are advised to turn over physics textbooks frequently, not just to review according to the materials, but to stay.
2. Senior three teaching should be people-oriented, because our teaching object is students, living people, not machines for listening to lectures, which requires us to be more humane in teaching, communicate with students, strengthen communication with students, establish a sense of service, and disconnect teaching from learning.
3. Let the students learn clearly, let the students understand: "It is better to make the 10 question clear than to do it in a muddle." In other words, in class, students should be made to understand why they should do this instead of that, and why it is right or wrong to do that, that is, they should always understand the word "reason" and speak it everywhere. In this regard, my experience is that I speak more and say less. In the future, if possible, I should let students talk about it.
In order to prevent students from entering the sea of questions, necessary questions should be done, but the questions must be carefully selected. Be sure to let students do it first, then speak, and then speak after speaking, and then leave time for students to digest and absorb.
5. Overcome the phenomenon of replacing learning with teaching. Without students' learning (understanding, digestion and absorption), teaching is futile no matter how good it is. Our position in the review of senior three should be: first, to guide students to sum up knowledge, fill gaps and build knowledge networks; second, to have a sense of service-to help students overcome difficulties and obstacles in their studies.
6. Efforts should be made to improve teaching efficiency. Efficiency depends not on how many knowledge points and topics you talked about today, but on whether the teaching goals you set before class are completed within the planned time. To put it bluntly, it is based on how much knowledge students can really learn in this course.
7. Pay close attention to the basic content and key content. The college entrance examination pursues discrimination. A set of successful test questions is realized through discrimination, not through difficulty, and the middle test questions are the real means to realize discrimination, because easy questions can't tell the good from the bad, and too difficult questions few people can tell the good from the bad. This point must be made clear to students. Only by paying attention to the foundation can we effectively complete the medium difficulty.
If you want to make a breakthrough in the college entrance examination next year, you can't just stare at a few good students. When top students have enough to eat, you should pay attention to those students who are middle-aged or weak in subjects. You should work hard to improve their physics scores, and the best way to improve their grades is to work hard to improve their interest in learning physics and make them move. This is the most effective method. In addition, you should care more about them and ask them more questions. Adopt flexible methods in teaching, such as assigning homework at different levels, and flexibly adopting different teaching methods according to the actual situation of each class to improve their learning enthusiasm.
We firmly believe that as long as we study hard, review scientifically according to the teaching rules, collect and process information in time, and fully mobilize students' learning enthusiasm, we will certainly achieve good results.