First, the application of physical projection technology in chemical experiment teaching
The purpose of demonstration experiment in chemistry class is to let all students observe the whole process of material change through experimental demonstration, gain direct perceptual knowledge, thus put forward questions and ideas, and draw conclusions through rational discussion. Creating teaching situations with the help of demonstration experiments can improve students' enthusiasm and participation in learning chemistry. Experiencing the authenticity and scientificity of the experimental process and convincing students are important ways to cultivate students' observation ability, and also create conditions for leading out topics and problems, discussing, exploring and discovering. Therefore, the demonstration experiment should really play the role of demonstration, and it is impossible not to demonstrate, so that the demonstration experiment becomes an experiment and the observation of experimental phenomena becomes an experimental phenomenon. In order to improve the visibility of demonstration experiments, the traditional methods generally use the methods of enlarging experimental instruments, raising experimental devices and increasing the dose of experimental drugs to show the experimental results. However, the magnification of experimental instruments is limited, and it is a waste of time to tour the experimental results. Moreover, some phenomena are produced instantly in the experiment, which cannot be observed and affect the teaching effect. Using physical projection technology can overcome the above defects and greatly improve the effect of demonstration experiment. For example, when demonstrating the composition experiment of primary battery, the key observation points in the experiment-the pointer deflection of galvanometer and the change of deflection direction are magnified by projection technology. By observing and analyzing the correlation between electrode replacement and current deflection direction, students can intuitively understand the composition of the primary battery and rationally analyze the influence of electrode materials on the primary battery, thus making the verification experiment more scientific; The deliquescence of sodium hydroxide on solid surface, the Dindar effect of colloid, the catalytic oxidation of ethanol, etc. are magnified by physical projectors to encourage students to observe chemical phenomena in life. The above experiments are very smooth when the teacher lectures, and students feel relaxed when they understand and master knowledge.
Physical projection technology mainly magnifies experimental phenomena, overcomes the defect of low visibility of demonstration experiments, and enables students to clearly observe experimental phenomena, especially some small and difficult-to-observe experimental phenomena. Projection technology improves the scientificity of the experiment, enhances the enthusiasm and participation of students, and provides a guarantee for cultivating students' observation ability.
Second, the application of multimedia technology in chemical experiment teaching
There are certain requirements for the operation steps and specifications of chemical experiments. Once students make mistakes in operation, it will not only lead to experimental failure and accidents, but also arouse students' fear and affect their interest in learning chemistry. Multimedia animation technology and typical software materials are used to simulate the consequences of easy operation. In this way, by allowing students to simulate the operation in front of the computer, they can master the correct operation and understand the incorrect operation, which will greatly improve the effectiveness of students' experiments. For example, when chlorine gas is prepared in the laboratory, the catheter should be taken out of the water after the experiment, and then the alcohol lamp should be taken out. Once wrong, it is dangerous. In order to solve this problem, the software of chlorine gas laboratory preparation is designed and made by multimedia technology, and some special treatments are made for this operation. In class, students are allowed to carry out repeated simulation experiments. Once the operation is correct, the computer will give reward tips to encourage students. Once the students make mistakes, the computer will simulate the dangerous scene of water flowing back to the bottom of the test tube and the test tube breaking. Another example is to simulate hydrogen explosion with untested purity, so that students can deepen their understanding of the harm caused by operational errors and then carry out correct experiments. Through the simulation of multimedia technology, not only the success rate of the experiment is improved, but also the importance of correct operation is deeply understood, which promotes students to establish norms and cultivate the potential of safety.
The application of multimedia technology to some experiments with complex equipment and operation provides students with a modular experimental environment, so that students can simulate the operation and train their experimental skills before conducting real experiments. For example, the preparation of CH3COOC2H5, in multimedia technology, students can master both the principle and the experimental operation method through simulation experiments, and constantly promote the improvement of students' experimental skills.
Multimedia technology plays an important role in the experimental design teaching of chemical experiments. Showing students' chemical knowledge and experimental operation skills is conducive to cultivating students' migration ability, problem-solving ability, mutual cooperation ability and creativity. In the multimedia "laboratory", students can swim in the laboratory, give full play to their talents and explore experiments in the chemical world. For example, the identification of substances, through the multimedia "laboratory" to provide students with the reagents they need, students design various methods for experiments and judgments. Computer can simulate various phenomena produced by various methods, and correctly judge and prompt them, which is conducive to cultivating students' consolidation, application and development of knowledge and cultivating students' creative spirit and ability.
Third, the application of camera and video processing technology in chemical experiment teaching
It takes a long time to demonstrate the whole process of the experiment, and with some irrelevant phenomena, it interferes with students' correct observation of the experimental phenomena and affects the effect of the experiment. Because students' classroom study time is limited, students should get as much information as possible in a limited time, and be selective when giving students information, so that the phenomena observed by students are valuable to their knowledge. Therefore, using camera and editing technology to deal with the whole process of the experiment not only provides students with the whole process of the experiment, but also highlights important experimental phenomena without losing the authenticity of the experiment. For example, the photolysis experiment of chlorine water can be played in class through this technology, which greatly enhances the timeliness of demonstration experiments. When students saw that chlorine water began to bubble slowly after a few hours of illumination, and obvious gas was produced after 24 hours, they not only confirmed the experimental conclusion, but also realized that some chemical reactions occurred slowly, which enhanced the effectiveness of students' observation experiments.
In demonstration experiment teaching, some experiments are harmful and dangerous, so it is impossible to demonstrate them in class. With the help of video teaching, the safety of students is guaranteed, the environment is protected and good teaching results are achieved. Through video recording technology, the harm caused by wrong operation in the experiment is truly reproduced, which attracts students' attention and helps them master the correct experimental operation steps and skills. For example, in the concentrated H2SO4 experiment, the correct operation is generally demonstrated in class, and the incorrect operation is explained. The phenomenon that concentrated H2SO4 drops into water and releases a lot of heat to splash H2SO4 liquid is demonstrated by video, so that students can deepen their understanding of this knowledge point. This kind of teaching can enable students to correctly grasp the experimental operation rules and correctly understand the experimental devices, which will play a certain role in the success of the experiment.
Demonstration experiment is the most effective way to help students learn basic experimental skills. For some complex experiments, students are given correct and standardized guidance by video recording, which avoids the defect of long time for teachers to demonstrate in real time. For example, in the teaching of chlorine preparation in high school chemistry experiment, video technology can be used to demonstrate, and at the same time, the precautions in operation can be partially enlarged and added to the narration introduction, so that students can understand "why to do this" and experience the correct operation to avoid the toxicity of chlorine. It provides a guarantee for students to finally master the nature of chlorine gas and correct experimental operation.
Using the functional effects of video recording technology can promote the authenticity of demonstration experiments, such as high-speed imaging or mosaic camera technology and the functions of fast, slow and anti-video projection, which can not only enable students to fully and carefully see the subtle differences of fast response, but also enable students to quickly observe the overall changes of slow response, so that students can quickly perceive the details that are easy to observe, improve the agility of students' observation, shorten teaching time, increase the timeliness of demonstration experiments and improve teaching efficiency.
Video and video splicing technology can also show more complex chemical production process, make abstract teaching content intuitive, and facilitate students to understand and master this kind of knowledge. Some expensive experiments, dangerous experiments, qualitative experiments, or experiments with complex equipment can also be completed with the help of teaching videos to ensure the safety, correctness, effectiveness and standardization of demonstration experiments.
Chemical experiment is the most commonly used and important teaching method in middle school chemistry teaching, which plays an important role in helping students understand and master chemical knowledge. With the development of science and technology, the integration of modern teaching technology, especially multimedia technology and experiment, will enrich the connotation of experiment, enhance the function of experiment, improve the efficiency of experiment teaching, and enable students to better improve their own quality in the integration of theory and practice.