Learning is an indispensable and important content in middle school physics teaching, which consists of
Because it is abstract, it has become a difficult point in physics teaching in middle schools. Thermal phenomena are common.
It is everywhere. Students have long-term relevant experience and are teaching heat.
A good cornerstone. But it is precisely because of this cornerstone, some incorrect views.
It is difficult to correct mistakes. According to the teaching experience and the investigation conclusions of relevant researchers,
Yes, both primary school students and middle school students, whether they have studied physics or not, have pictures.
When many people have an unscientific understanding of heat, one of the typical ideas is to put heat.
As a mobile substance. According to the current rich international science education
The widely influential learning theory, that is, the concept change theory, holds that: excessive scientific learning
Cheng is the process of conceptual change, and puts forward teaching for conceptual change. So as a middle school,
The main goal of physical heat teaching is to let students learn through heat.
Xi。 Realize the change of its concept and establish a scientific theoretical view of molecular motion.
In order to realize the change of ideas, many teachers and researchers have made various attempts.
Such as "learning by doing" and "experimental inquiry", to help students establish scientific enthusiasm.
Point of view, and achieved certain results. In this paper, the author tries to start from the utilization of heat.
Implement effective history teaching to help students change their ideas.
From the perspective of cognitive development psychology, individual students are interested in something.
When understanding, the level of understanding is the continuous interaction between subject and object.
Change and improve in the process. The process of personal knowledge development is the development of human knowledge.
The epitome of this process. Therefore, the level of individual cognitive development and human's historical understanding of it
The level of knowledge is corresponding. That is to say, it can be developed from human understanding of heat.
Predict students' understanding of heat. Then, in order to carry out effective thermal teaching, we should
It is necessary to introduce the history of thermal development to students. Historically, human beings have always been interested in "heat"
Thinking about what never stops. The understanding of heat is constantly changing and developing.
Can be summarized as the following three stages:
First, the formation of heat theory.
Influenced by ancient Greek atomism, heat is a special material entity.
French scientist and philosopher Gassendi thinks that heat and cold are the main reasons for this phenomenon.
It is also caused by special "hot atoms" and "cold atoms". Polhaf thinks that heat
Its origin is a highly plastic and penetrating thing, drilling in the pores of objects.
Mass particles without weight repel each other. This concept leads people to "heat"
Heat can be transferred from a high-temperature object to a low-temperature object, just like water falling from a height.
It flows downward. People think that heat is a special substance. It is hidden in the particles of matter.
Suddenly, attracted by matter particles, hot particles repel each other. In the18th century,
The "heat theory" dominated almost all thermal fields, and at that time, it could be simply compared with other theories.
Most of the thermal phenomena found at that time have been satisfactorily explained and some achievements have been made.
success
.
For example, the change of object temperature is caused by absorbing or releasing "hot mass"; thermal transmission
Conduction is the flow of "heat and mass", and so on. Under the influence of "heat theory", heat (mainly
Some progress has been made in the study of calorimetry, but in the end, the heat theory failed to make progress.
It is a severe challenge to explain the phenomena of thermal contraction, cold expansion and friction heat generation.
Second, the formation of qualitative thermodynamic theory
1658, Gassendi put forward the hypothesis that matter is composed of molecules, imaginary molecules.
Are hard particles that can move in all directions, so that they can be combined in different forms.
Show different characteristics. He used this hypothesis to further explain solids, liquids and gases.
A country. That is to say, inside the solid, hard particles are closely combined, and the particles are very strong.
Force keeps them in a fixed shape and particle arrangement rules; Inside the liquid,
The force between particles close to each other makes them difficult to disperse; In the gas phase
There is no interaction between distant particles, and each particle moves from the west. 55438+09
At the beginning of this century, with the establishment of chemical atomism, the concept of molecule was also put forward.
In recent years, the phenomenon of random movement of molecules has also been proved by experiments. In 1803,
Dalton (English chemist) studied the composition, properties and characteristics of the atmosphere.
The study of diffusion and mixing phenomena puts forward his basic viewpoint of new atomic theory.
That is, all chemical elements are composed of indivisible atoms; Various elements
Atoms are distinguished by their different shapes and properties and have specific masses; different
The atoms of elements combine with oranges in a simple integer ratio to form precursors of various compounds.
Son. At that time, Dalton was composed of different atoms because the concept of "molecule" had not been established.
Molecules are called "complex atoms". 18 1 1 year, Avon Gadereau (Italian physics
On the basis of Dalton's atomic theory, he began to introduce the concept of "molecule"
Read and distinguish it from the concept of atoms. 1827, due to Brown (British Botany
) Long-term observation and research found Brownian motion, which he did in the theory of molecular motion.
The new discovery provides strong evidence for molecular movement. Einstein +0905
From the point of view of statistical mechanics, Brownian motion theory is finally established and molecular motion is given.
This study provides a theoretical basis. Then Perrin in France was based on Einstein and others.
On the basis of theoretical research results, we have done experiments on Brownian motion for many years, from which,
When Avon Gadereau constant and molecular data are accurately determined.
Therefore, Brownian motion is the macroscopic expression of microscopic molecular motion and the heat of molecular existence.
There is strong evidence that there is a gap between movement and molecules.
Thirdly, the formation of fixed basin thermal theory.
Joule and others think that heat and mechanical motion are equivalent through a lot of experiments.
The form of motion, like it, is also a form of motion, not a special substance.
(thermal mass). After that, people made a quantitative and systematic study on thermal motion.
Research. Make the theory of molecular motion established. A lot of efforts have been made in the field of molecular motion theory.
There are many scientists at work, including Clausius, Maxwell and Boltzmann.
Work is particularly important. They are the main founders of molecular motion theory. Experienced a lot of things.
With the joint efforts of several agents, the theory of molecular motion was finally established. it
It not only reveals the relationship between the macroscopic "thermal" process and the microscopic motion state of molecules.
System, and shows that heat is the performance of random motion of a large number of molecules, a macro.
The thermodynamic state of a system is determined by the statistical laws of a large number of molecules that make up the system.
Yes This also shows that thermal motion and mechanical motion are completely different forms of motion.
The motion of a molecule follows Newton's laws of mechanics, and the motion of a large number of molecules follows the following laws.
Statistical regularity.
Fourthly, the enlightenment of the history of thermal development to thermal teaching in middle schools.
Physics teaching in middle schools does not require quantitative mastery of molecular motion theory, so
At present, middle school physics textbooks only involve some basic concepts of molecular motion theory.
Read, the content is as follows: (l) Macroscopic objects are composed of a large number of particles-molecules or atoms; (2) The molecules in an object are constantly moving, and this movement is irregular.
Its intensity is related to the temperature of the object; (3) There are interactions between molecules.
Force. It can be seen that for middle school students, as long as qualitative molecular motion theory is established.
This is the teaching goal of thermodynamics in middle school.
The truly effective teaching process is actually to find ways to shorten students' scientific cognition.
The time of understanding is no longer as long as that of human beings in history.
To explore, so in the teaching of heat, students' original experience can not be ignored.
Appropriate problem scenarios allow students to face the problems that scientists face at first.
Develop or change the original unscientific concept through inquiry. Understanding is recognized by human beings
How did you develop from caloric theory to caloric theory in history? What are the difficulties and how to break through them?
And so on, which is of reference significance to physics teaching in middle schools.
refer to
1 ding bangping. Introduction to international science education. Taiyuan: Shanxi Education Press, 2002.
Wu Ruixian, a native of Zhang Liyuan. Thermal research. Chengdu: Sichuan University Press, 1987.