This paper is my own experience in guiding the application of research-based learning in senior high school chemistry experiments;
First of all, make clear the relationship between chemical experiments and research-based learning:
In middle school chemistry teaching, it is of great significance to make full use of the basic characteristics of chemistry subject "experiment-oriented" and explore and develop the role of chemistry experiment in research-based learning, which will change students' learning methods and form lifelong learning ability.
1. Chemical experiment is an important way of inquiry learning.
Inquiry learning is a process in which students acquire knowledge and skills independently, experience and understand scientific research methods, form and improve innovative consciousness, and establish scientific values and activities. Chemical experiment is a dynamic form of practical activities in students' chemical learning. Chemistry experiment creates a situation in which students personally participate in practice, which has educational functions such as learning, stimulating interest, seeking truth, reasoning and educating morality. The function of chemical experiment and the characteristics of inquiry learning determine that chemical experiment must be an important way of inquiry learning.
Second, chemical experiments as a teaching strategy of research-based learning
In chemistry teaching, we should advocate and encourage students to carry out research-based learning through chemical experiments, fully tap the role of chemical experiments in research-based learning, give full play to the role of chemical experiments in creating problem situations and verifying hypotheses or conjectures, research and develop research-based experiments, guide students to discover and study methods to solve problems through experiments, cultivate students' scientific quality in chemical experiments, and realize the fundamental change of students' learning methods from passive acceptance to active research-based learning.
Second, the choice of chemical experiments and research-based learning topics:
To carry out research-based learning through chemical experiments, we must pay attention to cultivating students' chemical experiment ability and autonomous learning ability, and at the same time determine research topics according to students' knowledge ability, especially choose appropriate research topics according to students' chemical experiment ability. According to our experience in carrying out research-based learning and following the principle of subject research, we mainly adopt the following methods to select topics.
First, choose research topics in combination with chemistry teaching. The important task of today's curriculum reform is to improve students' practical ability and innovative spirit, and appropriately increase some exploratory experiments, which is conducive to improving students' exploration desire and cultivating students' innovative ability. For example, the transformation of Fe2+ and Fe3+ can be improved into exploratory experiments: according to the existing experimental conditions, how to realize the transformation of Fe2+ and Fe3+? Let the students design the experimental scheme first, then exchange design ideas, choose the best scheme, and finally carry out the experiment and draw the experimental conclusion. This exploration process can mobilize students to actively participate in information processing, use a variety of senses to construct knowledge, and make students' potential better developed.
Second, choose research topics in combination with daily life. Problems in social life are everywhere. We guide students to think from their own perspective, ask questions, screen and determine research topics, and then let students collect information and study experimental schemes. Through experiments, they can explore and learn independently, and greatly exert their innovative ability. For example, to explore the causes of iron rust, students choose various common iron parts in life and design different conditions for experiments. On the other hand, students go to factories, shops, residential areas and rural areas for on-the-spot investigation. Students have a comprehensive and profound understanding of the causes, hazards and preventive measures of rust, and have written high-quality chemical papers.
Third, select research topics according to local production practice. We combine the actual situation of local economic construction, extracurricular activities and practical activities to let students explore boldly and innovate actively. For example, around water problems, students can be inspired to think about water resources, utilization, flood, pollution, monitoring, prevention and control in our county. Students are very enthusiastic and ask many questions. They investigated sewage outlets, visited waterworks, and monitored the pH value of water and the contents of heavy metal ions and phenol. And invited environmental protection bureau personnel to analyze, and achieved good social benefits.
Fourth, select research topics in combination with extracurricular activities in chemistry. Using extracurricular small experiments, interesting chemical experiments and chemical magic, we actively explore the design scheme of chemical experiments, and study the phenomena, experimental devices, experimental operations, experimental observations, experimental records, experimental analysis and experimental reports of chemical experiments. For example, the principle and method of self-made soda, the analysis of scale components in hot water bottles (boilers), the exploration of the principle of photo development and so on.
Thirdly, that application of inquiry learn in chemistry experiment:
1. Design the experimental scheme
Teachers put forward the purpose of the experiment, let students design the experimental scheme, and then teachers and students discuss it one by one to find out a variety of schemes or determine the best scheme. For example, when studying the content of manufacturing ethylene in the laboratory, it is first explained that ethylene will be mixed with SO2 and CO2. Let students design experiments to prove their existence. Results All the students knew that the gas had to pass through a gas cylinder filled with magenta solution, and the magenta faded, which proved that there was SO2 gas. However, in the next operation of testing the presence of CO2, opinions were divided, and the students put forward the following schemes: ① introducing gas into the clarified limewater, and the limewater became turbid; (2) After the gas passes through a gas washing cylinder filled with sufficient sodium bicarbonate solution, it is introduced into clear limewater, and the limewater is turbid; (3) The gas passes through a gas washing cylinder filled with acidic KMnO4 solution, and the solution fades, and then it is introduced into clear limewater, and the limewater becomes turbid; (4) The gas passes through a gas washing cylinder filled with acidic KMnO4 solution, and the solution does not fade, and then clear limewater is introduced, and the limewater becomes turbid; ⑤ Pass the gas through a gas washing cylinder filled with magenta solution again, and the magenta does not fade, and then introduce clear limewater, and the limewater becomes turbid. Then, teachers and students discussed: Schemes ① and ③ did not bring SO2, which may not fully react with magenta solution, into clarified stone water, and the schemes were unreasonable; Scheme 2 completely removes SO2 gas, but the reaction of SO2 with nahco3 solution will produce CO2 gas, which is obviously unreasonable. Schemes ④ and ⑤ can not only completely remove SO2 gas, but also reduce or generate CO2 gas, and the phenomenon is obvious, so the above two schemes are reasonable.
2. Improve the experimental device
Some experimental devices in textbooks are complex, time-consuming and medicine-consuming, some experimental phenomena are not obvious enough, and some experimental environments are seriously polluted. Teachers can guide students to improve these experiments. For example, after the experiment of preparing phenolic resin, the test tube is difficult to clean, and we have to replace the test tube every time. After improvement, we use the vial of fosfomycin, a medical waste, instead of test tubes, which not only saves a lot of test tubes, but also reduces the dosage of drugs.
3. Study the influence of different reaction conditions on the experiment.
After the experiment of NaOH solution dropping into AlCl3 solution, students are required to reverse the order of the above experiments, observe the phenomenon and explain it. Another example is that the reaction speed of pure zinc particles and dilute sulfur is slow, and a small amount of CuSO4 solution is added to the reaction mixture, which greatly accelerates the reaction speed and allows students to explore the principle.
4. Conduct small family experiments.
Small family experiments do not give drugs, instruments, steps, phenomena, etc. Relying on students to do it independently at home plays a very important role in cultivating students' innovative spirit and practical ability.
In a word, carrying out research-based learning through chemical experiments and putting the teaching and educational concept of research-based learning into chemical experiments have enhanced students' initiative and interest in carrying out research-based learning. The improvement of students' chemical experiment ability promotes the development of research-based learning activities and improves the quality of research topics; On the contrary, inquiry learning further improves students' experimental ability and practical ability, and promotes the all-round development of students' innovative ability and comprehensive quality. At the same time, students have established perseverance and perseverance in experimental research, and developed the scientific spirit of pursuing truth and seeking truth from facts.