Keywords: textbook, physical thinking method, physics teaching
"Physics Curriculum Standard for Full-time Compulsory Education" points out that "through the combination of scientific imagination and scientific reasoning methods, students' imagination and analytical generalization ability can be developed, so that students can develop good thinking habits, dare to question and be brave in innovation. "Therefore, paying attention to the cultivation of thinking ability is one of the important goals of physics teaching; On the other hand, the physical thinking method is also the summary and generalization of the thinking method and scientific method adopted by people in physical research and practice. It can not only improve the efficiency of physics learning and promote the learning of physics knowledge, but also cultivate a scientific world outlook and develop students' ability to think and solve problems independently. In many years of physics teaching, the author found that there are many physical thinking methods in textbooks, which can make full use of textbooks to carry out physics teaching activities and infiltrate the education of physical thinking methods.
First, the main physical thinking methods contained in the textbook
1. Physical model thinking method
The thinking method of physical model refers to the thinking method of making full use of physical model for analysis and synthesis in the process of learning physics. The so-called model is to focus on the essence and solve problems, and take some simple models to study complex physical processes and branches of research objects. There are two kinds of physical models: one is to regard the research object as an abstract ideal model. Such models include particles, ideal gas, spring oscillator, simple pendulum, point charge, point light source and so on. The second is to abstract the physical process into an ideal model. This kind of model includes uniform linear motion, complete elastic collision, steady current and so on. The same object can be divided into several physical models. For example, when studying the gravity between the sun and other celestial bodies, the sun is regarded as a particle; When studying its rotation, treat it as a rigid body; When it illuminates the earth's surface, it is regarded as a parallel light source.
Different physical models will come to different conclusions about the same problem. The principle of choosing a model is as simple as possible according to the given conditions. In all kinds of physics textbooks, it is sometimes clear which model is discussed, such as particles and light. But most occasions do not explain, teachers need to think for themselves. For example, within the scope of mechanics, it is self-evident that stones, balls and bullets are particles. In the rotating part, lever, flywheel, etc. It should be a rigid body. Senior high school compulsory 1 page 10: "In physics, it is a common scientific research method to highlight the main aspects of the problem, ignore the secondary factors and establish an idealized physical model as the research object. Particles are one such physical model. " Page 4 1 of Volume 3-2 also shows that the ideal transformer is also an idealized model.
2. Physical deductive thinking method
Physical deductive thinking method is the application of inductive and deductive thinking in physics research. For example, in the process of deducing gravity, we talked about the discovery of Neptune. 19 In the 1940s, when French astronomers studied the observation data of Uranus, they found that its position was different from that calculated by astronomy. He deduced from the general law of gravity that this deviation was due to an unknown planet attracting Uranus. He told the Berlin Observatory the calculated orbit and predicted position of the unknown planet. Later, the German astronomer Galle observed this planet, Neptune.
3. Physical analogy thinking method
In the process of physics research, many conclusions are based on physicists' analogical thinking. When talking about these places, you can use examples from textbooks to illustrate them. For example, a simple pendulum, we know that when the swing angle is less than 5 degrees, the vibration period of a simple pendulum with a certain swing length has nothing to do with the amplitude and the pendulum ball. This is called the isochronism of simple pendulum vibration, and the isochronism of pendulum is the conclusion reached by Galileo through analogy. Galileo, a young man, observed the swinging of the oil lamp hanging in the church and found that although the swinging amplitude of the chandelier was getting smaller and smaller, the time seemed to be equal every time. Before the clock, Galileo used his pulse to beat regularly. He followed his pulse and watched the chandelier swing. By analogy, the observation result is correct.
4. Equivalent principle thinking method
Physics in senior one, I know uniform linear motion. But when discussing variable speed movement, the speed of movement is uneven. When the average speed is introduced, the variable-speed motion experiences a period of displacement, which is equivalent to a uniform linear motion with the same displacement at the same time. The speed of variable speed motion is roughly described by the ratio of displacement to time. However, this is not speed, but average speed. Therefore, when discussing the average speed, we must be clear about which time period and which distance effect counts. At another distance, at another time, it may not be the same.
5. Dimension verification thinking method
Base quantity and derived quantity. Several physical quantities are pre-selected as basic quantities. Because the basic quantity is the unit that derives other physical quantities according to the physical formula, it is called the derived unit. The international general unit quantity applicable to all measurement fields is called the international system of units. Within the scope of mechanics, the international system of units stipulates that length, mass and time are three basic quantities, and they use meters, kilograms and seconds as basic units. Velocity, acceleration, force, momentum and work are all derived quantities. Their units m/s, m/s, Newton, kg m/s and Joule are all derived units. The author thinks that dimensional verification thinking method is often ignored by some teachers and students, but in fact it plays an important role in physics learning and problem solving.
6. Scientific conjecture thinking method
Combine daily life experience with exploring physical laws and make scientific guesses. For example, when learning Archimedes' principle, contact the well to get water. When the bucket leaves the water surface, it feels that the bucket is getting heavier gradually, so it can be inferred that the buoyancy may be related to the volume of the object immersed in the liquid. You can also contact the difference between swimming in the river and swimming in the sea. It is speculated that buoyancy may be related to liquid density. Observe exploratory experiments, gain qualitative understanding and make scientific guesses. For example, when junior high school physics does an exploratory experiment to study the relationship between liquid pressure and depth, it is first concluded that the depth in the liquid is the same and the pressure in all directions is equal. Then, recognizing that the internal pressure of liquid increases with depth, we scientifically guess the relationship between the pressure and depth of liquid.
7. Ratio method and reduction to absurdity method
The application of ratio method and reduction to absurdity in physics is reflected in textbooks many times. Page 15: here we define a new physical quantity (speed) by the ratio of two physical quantities (displacement and time), and its physical meaning is completely different from the original two physical quantities. In physics, ratio is often used to define physical quantities to study some new knowledge of objects, such as density, moving speed, pressure and so on. In fact, this method is often used in other fields, such as per capita arable land area, per capita income, commodity unit price and so on. Physics in senior high school 3- 1, page 19, used the reduction to absurdity when discussing the relationship between equipotential surface and electric field lines, which is an important logical method in scientific research.
Second, the ways and methods of infiltrating physical thought and method education with teaching materials
1. Infiltrate activities to guide students to preview their homework.
Preview homework can help students have a clear aim in classroom teaching and fully integrate what they have learned in preview with what they have learned in classroom teaching activities organized by teachers. When students preview their lessons, teachers can intentionally draw students' attention to what is said in the book, thus infiltrating the education of physics thinking methods. For example, before learning the law of gravity, teachers guide students to preview activities. The teacher explained the experimental philosophy "analysis-synthesis method" founded by Newton to the students. Analysis method: experiment, induction and deduction are combined to find the law; Comprehensive method: establish deductive principle-establish the law of theoretical discovery-verify the truth through practice.