What are the principles followed in controlled experiments?

1. Controlled experiments.

The concept of "control experiments" in which the effects of one condition on a subject are studied and the conditions are the same except for those conditions. Experiments in which all but one factor remains the same are called controlled experiments.

2. Single variable principle: According to the single variable principle, it is one of the guidelines for dealing with complex relationships, simplifying complex problems. Only the factors to be studied are different in different experimental groups, and all other factors influencing the experiment are the same.

The three basic principles of experimental design are the control principle, the random principle, and the repetition principle.

1. The principle of control, the design of control experiments can eliminate the interference of irrelevant variables on the experimental results, so that the experimental results are scientific. Designing experiments can be divided into experimental group and control group. The experimental group is the group of objects that are treated with experimental variables; The control group, also known as the control group, is the group of subjects who do not accept the treatment of experimental variables in relation to the experimental hypothesis.

2. The principle of randomness is the basic principle of experimental design—the principle of repetition and randomization. Implementing the principle of randomization is an important means to improve the balance between groups. It is also a prerequisite for statistical inference during statistical analysis of data.

The key to implementing the principle of randomization in the experimental design is to ensure that each test subject has a large test and that the collected subjects have an equal chance of being randomly assigned to the control group and the experimental group.

3. Repetition principle: Repetition means that the number of cases (or number of experiments) in each treatment group and control group should have a certain number, that is, there should be enough sample content.

**Design Principles for Sex Trials:

1. The principle of sexual design.

** The principle of sexual design refers to the fact that the physical laws contained in the designed experiments are often hidden at a deep level and need to be explored by students; The way to solve the problem is often not clear, and students need to find it by trying and making mistakes, formulating hypotheses, and testing hypotheses.

2. Interesting design principles.

The principle of interesting design refers to: the design of sexual experiments should fully consider the psychological characteristics and cognitive level of students, and the experimental design should be vivid and interesting, so that students can maintain a high interest from beginning to end when conducting experiments. Sleepy Lee.

3. The principle of linking theory with practical design.

The principle of linking theory with practice refers to the fact that the design of physical experiments not only involves the process of observation and measurement, but also requires the establishment of physical models, and the interpretation of the phenomena and results of the experiment with the expressions derived from the physical model, so as to cultivate students' ability to use theory to solve practical problems.

4. The principle of simplicity design.

The principle of simple design means that the design of the actual test should use as few instruments as possible, the instruments used should be as simple as possible, the design topics should be related to the reality of daily life as much as possible, and the principle of the experiment should be within the scope of physics in middle school as much as possible.

The main function of setting the control is to eliminate the interference of other factors in the experimental results.

When studying the effect of one condition on the study subject, a set of Qichun control experiments were carried out except for the difference in this condition, and the other conditions were the same.

, there needs to be an experimental group and a control group.

The experimental group is the object group that receives the treatment of experimental variables, and the control group is the object group that does not accept the treatment of experimental variables, and the control group plays a control role in the experiment.

There is no clear definition in biology between the experimental group and the control group, just like the "set" in mathematics, which is just a basic concept.

**Sex experiments are mainly aimed at cultivating students' ability to innovate.

The following basic principles must be adhered to when designing,1Scientific principle: ** The scientific nature of the experiment is very strong, and the experimental principle is very strong.

The experimental operating procedures and methods must be consistent with the theoretical knowledge of chemistry and the scientific experimental research methods. In the whole process, it is necessary to focus on cultivating students' scientific thinking methods, observing and recording experiments, so as to improve students' scientific quality, which is also the purpose of adding first-class experiments.

2.The principle of creativity: the first experiment designed by the teacher should have a certain degree of novelty, advanced and experimental, and should fully reflect the principle of creativity Use creative thinking to understand new knowledge independently, conform to the cognitive structure of students, and be easy to reach.

Difficult, step by step.

3.Feasibility principle: The content of the subject is mainly the sublimation of book knowledge, which should usually be closely integrated with daily life, production practice and advanced science and technology, but can not exceed the age characteristics and knowledge range of students, that is, the design experiment must be practical and feasible, so that students can successfully complete the task.

Neither underestimate nor overestimate the level of the students.

4.Safety Principle :** Sex experiments are generally difficult, and students are inexperienced, so they should try to avoid the use of toxic drugs and experimental operations with certain dangers.

5.The principle of interest: In addition to the textbook, the experimental content should also be selected to solve the problems closely related to human beings themselves, so as to cultivate students' interests, develop students' strengths, stimulate students' motivation to learn, and increase their exploration of new knowledge.

Changing chemistry to biology, the principle is the same. 】

Answer]: Modulus cheating e

Analysis: Balance The control principle means that a control group must be set up in the experimental design in order to identify the effect size of the experimental group by comparing it with the control effect. Only by setting up a control group can the influence of non-treatment factors on the experimental results of the Dan ethnic group be eliminated, so that the effects of experimental factors can be reflected (e).

Ensuring the balance between groups is one of the conditions for the control group.

Answer]: A analysis: The control principle is one of the criteria for the design and implementation of the experiment, and the influence of irrelevant variables can be excluded by setting up the control comparison, and the reliability and convincing of the experimental results can be increased.

There are three principles of experimental design: the random principle, the control principle, the repeat principle, and the slip rule. It is only through the establishment of the control group that we can clearly see the role of experimental factors in this.