1. The role of scientific experiments
Scientific experiment is an important factor to promote scientific development and production technology change. It can be said that all major scientific discoveries and inventions are extracted from scientific experiments. Classical mechanics, optics, electromagnetism and chemistry are all based on scientific experiments. Therefore, without experiments, there can be no modern natural science and no development of modern natural science.
In addition to exploring and discovering the truth, scientific experiments also have a function of testing hypotheses, that is, verifying and developing the truth. Assumptions and speculations in scientific research can only be proved to be true through experiments or observations. Yang Zhenning and Li Zhengdao's hypothesis that micro-particles are "parity-nonconservative" under weak interaction is confirmed by Wu Jianxiong's experiment. Of course, the analysis of experimental results and the explanation of phenomena still depend on the guidance of theory (which has also been proved by experiments). Therefore, practice and theory are always interdependent, and theory is constantly deepened and developed through scientific analysis and summary. 2. Several concepts of experimental research?
(1) What is a hypothesis?
Once you know what you are studying, you should establish research hypotheses. The so-called research hypothesis is to put forward hypothetical views and explanations on research problems according to certain observation facts and scientific knowledge. In fact, the research hypothesis is the temporary answer to the research question. Because after observing the things around you, you will have some questions, and then you will think about them. You will make a tentative answer to your question according to your own understanding, or consult relevant materials or consult relevant personnel. There is not much difference between hypothesis and theorem or conclusion, except that hypothesis is a theorem or conclusion to be proved, and theorem or conclusion is a confirmed hypothesis. There is only a degree difference between the two, but there is no difference in essence.
Hypothesis is our point of view when we first started to study the problem. There are some guesses and assumptions, but there must be some scientific basis, some facts or theoretical basis, and it is not a fantasy. It is different from myth, fantasy and superstition in principle. Scientific hypotheses must be verified by experiments. For example, if the switch light is not on, there may be several assumptions: ① power failure; ② Poor contact of socket; (3) the fuse is blown; The light bulb is burnt out. These hypotheses can be directly tested.
The formation of hypothesis depends on scientific knowledge. In the development of science, two or more different hypotheses can appear in the study of the same problem. This is because the factual materials and scientific knowledge on which the hypothesis is based are limited or different, and different assumptions are bound to be drawn. Middle school students have mastered certain scientific theories and knowledge, which is the basis for your research hypothesis. However, we still need to consult some materials or teachers and experts to gain some knowledge. In the process of consulting materials and relevant personnel, it is also a good learning opportunity to expand your knowledge.
In scientific research, we often use experiments to verify a hypothesis. In the process of experiment, two concepts-constant and variable are often involved.
(2) What is a constant?
In the discussion of mathematical or natural science problems (or under certain conditions), the quantity that remains constant is a constant. For example, pi ≈ 3. 14 1.59, and the base of natural logarithm e ≈ 2.7 1.828 are all constants.
In social science research, constants refer to the characteristics and conditions of all individuals in the research topic. For example, in the study of comparing the influence of two different teaching methods on the academic performance of fifth grade students, the grade level is a constant, because this characteristic of fifth grade is the same for everyone and is an unchangeable condition in the research course.
(3) What is a variable?
Variables generally refer to the conditions or characteristics that researchers manipulate, control or observe. Variables are also called "variables". When discussing mathematical or natural science problems, we can take quantities with different values. For example, the distance an object moves is a variable. In social science research, variables refer to the characteristics of different individuals with different values or conditions. For example, when studying the influence of two different teaching methods on the grades of fifth-grade students, each student's grades are a variable. There are many kinds of variables, the common ones are independent variables and dependent variables.
The terms independent variable and dependent variable are derived from mathematics. In mathematics, in the equation y=f(x), x is the independent variable and y is the dependent variable. The dependent variable varies with the independent variable. For example, the color of the indicator changes with the pH of the solution. When the solution is acidic, phenolphthalein indicator is colorless; When the solution is alkaline, phenolphthalein indicator is red; Therefore, the acidity and alkalinity of the solution is an independent variable, while the color change of phenolphthalein indicator is a dependent variable.
In social science research, independent variables are often classified variables. For example, to study the influence of different teaching methods on academic performance, researchers should first adopt different teaching methods, and then measure and compare the changes of students' academic performance. In this case, different teaching methods are independent variables and students' academic performance is dependent variable. Here the independent variable is in the position of cause, and the dependent variable is in the position of effect.
3. Classification of scientific experiments
There are various methods of scientific experiments. According to the purpose and characteristics of experimental design, experiments can usually be divided into several categories. Here we introduce several experimental methods that may be applied to "inquiry learning" activities:
(1) qualitative experiment.
Qualitative experiment is a research activity to judge the nature of the experimental object and its external relations, the factors affecting the nature and their mutual relations, such as judging the composition of a substance and exploring the internal structure of the research object. Franklin's kite experiment, Faraday's electromagnetic experiment, Hertz's electromagnetic wave experiment and Michelson-Morey's experiment of denying the existence of "ether" are all qualitative experiments. Qualitative experiment is a preliminary experimental method to identify the essence of things. In order to understand the research object more deeply and comprehensively, quantitative experimental methods must be adopted.
(2) Quantitative experiment.
Quantitative experiment is a research activity to measure the quantity of the research object and the relationship between quantity and quantity, and on this basis, to obtain empirical formulas and empirical laws. Such as thermal mechanical equivalent experiment of Joule measurement, Fizeau experiment of light speed measurement, parts wear experiment in engineering, bearing life experiment, fuel consumption experiment of internal combustion engine, etc. Qualitative experiment is the basis of quantitative experiment, and quantitative experiment is the deepening of qualitative experiment. Only by measuring the relevant data of the research object and expressing it with mathematical formulas can we accurately grasp the essence and motion law of things and have a deeper understanding of this thing. In addition, in scientific research, qualitative experiments and quantitative experiments cannot be absolutely separated, because everything is composed of certain properties and certain quantitative relations. Therefore, we should also pay attention to the concept of quantity in qualitative experiments. Without the concept of quantity, it is sometimes difficult to distinguish the quality of different things.
(3) Factorial experiment.
Factorial experiment is a research method to find unknown reasons from known results and analyze causality. For example, why milk turns sour was first discovered by French biologist Pasteur through experiments. For another example, a lot of heat will be generated in the process of metal cutting, and the experiment to find out the factors affecting cutting heat and the influence degree of various factors on cutting heat is also a factorial experiment. When using factorial experiment, we should try our best to grasp various factors that affect the results. Because the change process of anything, or its result, is often influenced by many reasons or factors, rather than the result of a single factor.
(4) Control experiment.
Control experiment, also called contrast experiment, is a research method to analyze and study through comparison to reveal some characteristics of the object. The method of control experiment is to divide the subjects into two or more equal groups, one of which is the control group as the comparison standard and the other is the experimental group. Different experimental conditions and environments are given to distinguish some of their characteristics, and experimental data and conclusions are obtained by comparison.
4. Steps of experimental research
Make an experimental plan
When making the experimental plan, we should focus on the following issues: collecting relevant information and literature; Determine the experimental content; Choose the experimental method; Arrange the experimental time; Implement experimental instruments and equipment; Determine the experimental materials or objects; Predicting experimental results; Wait a minute.
(2) Organizing the implementation of the experiment
Control the experimental conditions as planned and collect experimental information in time, including the recording of experimental phenomena and the determination of quantitative factors. , and pay special attention to keep the original records.
(3) Sort out the scattered data obtained in the experiment process to form intuitive and organized data, which is beneficial to the next analysis and research. The obtained data can be sorted out in the form of tables.
(4) Analyze the test results.
Analyze the data obtained in the experiment process, find out the characteristics, characteristics, laws, etc., and draw a conclusion.
(5) Write an experimental report.
Write the experimental report as required. The contents of the report can be divided into topics, questions, research process, research methods and contents, conclusions and so on.
5. Requirements for scientific experiments