First, step by step;

Second, reading a book a hundred times is self-evident;

Third, professional counterparts;

Fourth, reading is the main source of knowledge.

First, build a personalized knowledge structure step by step.

1. Chasing the frontiers of disciplines.

There is a middle school in Beijing. After the freshmen entered the school, the school invited a doctor of chemistry from Peking University to give them their first lesson. The content of the class has nothing to do with the existing textbooks. He talked about six frontier fields of chemical research. For example, he said, we are short of water resources now, but there are enough fresh water resources under the sea floor. But this fresh water does not exist in liquid form, but in solid form, which is called roller skating. Roller skating can be used, but it must be melted first. In the process of liquefaction, a large amount of carbon dioxide will be produced. No one dares to do it now, because if anyone melts roller skating into liquid, the whole earth will be filled with carbon dioxide. So who can successfully solve this contradiction, that is to say, carbon dioxide is not produced during roller skating liquefaction, or carbon dioxide is decomposed by other reduction reactions, then the problem of fresh water shortage will be completely solved, which will be a great contribution to the world.

Mathematician Chen Jingrun can successfully complete the study of number theory. One of the most direct reasons is that his middle school math teacher told a story. Once, his math teacher said, "Let me tell you a story," with five minutes left in the lecture. I told the story of Goldbach's conjecture. He said that whoever successfully developed Goldbach's conjecture won the jewel in the crown of mathematics. This sentence had a lifelong impact on Chen Jingrun. From then on, he tried to take off the jewel in this crown. The story aroused his lofty sentiments. He worked hard for more than twenty years and made great contributions to solving Goldbach's conjecture.

2. Establish a personalized knowledge structure.

Knowledge is infinite, and the knowledge that an individual can master is limited. It is a realistic choice to make their limited knowledge have comparative advantages and development characteristics. In fact, everyone has their own areas of interest and expertise; Interested and good at it, it is easy to form a comparative advantage. But for a long time, we have understood all-round development unilaterally and always tried to cover everything, resulting in mediocre development and becoming a reading machine. Here, I want to put forward an important concept, namely personalized knowledge structure. According to the research of curriculum experts and psychologists, knowledge has an internal structure and knowledge is not equivalent in the whole knowledge system. If you master the elements of knowledge, you can master the knowledge structure and achieve mastery.

Second, change from passive acceptance learning to active inquiry learning.

To stimulate the enthusiasm of learning, the most important thing is to turn the learned knowledge into inquiry questions. In modern learning, learning knowledge and exploring questions should be reversed. In traditional teaching, learning knowledge is the purpose, and helping to master knowledge through problem guidance is the means; However, in modern learning, learning knowledge is a means, and being able to apply it to solving problems is the purpose. Whether you can learn to find problems, find problems, analyze problems and solve problems in learning is the fundamental criterion to measure the success or failure of learning.

Problem-oriented teaching combines knowledge learning with future ability demand, and changes passive knowledge infusion into ability training. In knowledge-based learning, students are in a state of passive acceptance, waiting for correct answers and lacking enthusiasm; In problem-oriented learning, there is no standard answer, and getting the answer itself is not important. What matters is the process of exploring the problem. In this process, students can become real subjects and active explorers.

Third, change from linear learning to T- learning.

Learn from change. Whether a professional talent can adapt to this change in the changing trend of the world, become a T-type talent, become a compound talent, and become a talent who can constantly adjust his knowledge structure and technical structure determines the possibility of this person's development in society.

The level of modernization in America is the highest. Statistics show that Americans have 17 times on average in their lives. Of course, this mobility change includes job hopping. But mainly because society is changing, so are individuals. If you are 40 years old and apply for a job, the boss asks you, "How many times have you chosen a job?" If you answer, "This is the second time I have chosen a job, and I used to work in one place." The boss will be surprised and ask, "You haven't changed jobs for more than 20 years?" That's unimaginable and incredible.

Fourth, from learning knowledge to learning.

No matter how much knowledge a person has, compared with the internet, it is like a drop of water in the sea, and the difference between a drop of water and a drop of water can be ignored. The problem is how to find, analyze and judge the knowledge you need from the network, and more importantly, how to use the knowledge on the network. At present, I mainly study, and I don't feel the urgency of this problem. But when you step into the workplace and society, you will find that whether you are good at finding knowledge from the Internet to solve practical problems determines your position, income and development prospects in the workplace.

In the past, the foundation and application, theory and technology were decomposed, but now this is not the case. Theory should be combined with practice, theory should be combined with technology, and theory should use methods. Because an important feature of social development now is that the speed of transformation from theory to technology is accelerating. The change of theory and technology is almost synchronous, especially in the emerging field of science and technology. Those who study technology do not master theory, and those who study theory do not master technology, which is not only bad for individuals, but also bad for the country. This concept of talent differentiation has not adapted to the needs of modern society.

Foreign students spend the longest time in the laboratory, while Chinese students spend the shortest time in the laboratory. Many courses have regulations: the experimental class is 50 minutes or 100 minutes, but in fact, the experimental time has not yet arrived, and everyone in our school has left. Why? Everything is done, including the steps. Because before you do an experiment, you should be clear about what experiment to do, what medicine to use and how to use it. When you get to the lab, just verify the experimental results and leave when you are done. In American schools, teachers don't care about what experiments to do, but only instruct students what experiments to do according to what they have learned, but let students choose which experiments to do. Students tell the teacher what experiment they want to do and how to do it, and make a list of the required equipment. After the teacher agrees, let the students find it themselves. Students go to a special drug classroom to find drugs and design experimental steps. If no experiment succeeds, everyone will fail. For example, water is dissolved by electricity, producing hydrogen and oxygen. You need electricity, water, beakers, etc. Make a list yourself, and the teacher will get it if he says yes. After receiving it, you can do it. In most cases, you can't succeed once. It doesn't matter if you don't succeed. Go to class first and do it after class. Write down everything you do every time, including the analysis of the reasons for failure, and verify it next time. Three failures, four failures, and finally success. How did you succeed? Write it down. One, two, three, four, five. This is the experimental report. This is a combination of theory and practice, and it is a learning way to promote the transformation from theory to technology.

Five, actively organize and participate in social activities

Only in the process of social communication, facing different interests, different viewpoints and different hobbies, and in the process of conflict and compromise, can we really learn the qualities and abilities of "taking care of the overall situation", "unity and cooperation", "initiative" and "strategizing", establish a sense of responsibility, really exercise leadership ability, and be familiar with public activities without stage fright, retreat, activities and activities.

As long as social activities are not excessive, it will not only affect learning, but also help improve academic performance. Because, first, there are many similarities between social quality and learning quality, such as purpose, self-discipline and resilience, such as integrity, classification, abstraction and generality, which are essentially the same; Second, in social activities, we can improve our self-confidence and sense of responsibility, learn to predict and judge the outcome of things, increase our understanding of our personality characteristics, including strengths, weaknesses and deficiencies, and increase our self-awareness, thus improving our ability to plan ourselves.

(B) Inquiry teaching

First, the significance of scientific inquiry:

According to the definition in the Oxford English Dictionary, inquiry is "an activity of seeking knowledge or information, especially truth, an activity of seeking, researching, investigating and testing, and an activity of asking questions and questioning."

Inquiry in American national science education standards: inquiry is a multi-faceted activity that needs to be observed; Need to ask questions; Need to consult books and other information resources in order to understand what you already know; Need to involve research projects; It is necessary to test what is already known according to experimental evidence; Need to use various means to collect, analyze and interpret data; Need to provide answers, explanations and predictions; It is necessary to tell people the results of the research. Inquiry requires clear assumptions, critical thinking and logical thinking, and other possible explanations are considered.

1. Scientific inquiry is an activity.

Science is a process, and the best way to learn science is to engage in science. Scientific inquiry is an important practical activity for students to actively acquire chemical knowledge, understand and solve chemical problems. Activity is opposite to the traditional "sitting" and "listening" to learn science, which allows students to get close to science and actively explore science with their hands and brains.

Activities are not fleeting, and scientific inquiry activities do not go from finding problems to solving them overnight. They need to go through a process, which mainly involves asking questions, guessing assumptions, making plans, conducting experiments, collecting evidence, explaining and summarizing, reflecting and evaluating, and expressing communication. Considering the limitations of students' learning level, the characteristics of inquiry contents and conditions, not every scientific inquiry process should include the above eight elements, and each element may not be presented in the above order.

2. Scientific inquiry is an important way of learning.

Science is not only some concrete facts and abstract theories, but also a process. Science is based on inquiry, and the research on science should also be carried out in the way of inquiry. Scientific inquiry, as a way of learning, means that we should take inquiry as an important way for students to know nature and the material world, as a way to think and explore the world we live in, and as an effective means to acquire knowledge. We should learn science by exploring rather than accepting. Inquiry learning mode advocates that knowledge is not directly imparted to students in the form of conclusions, but requires students to have direct contact with learning objects, which can only be obtained through independent exploration and discovery. From this perspective, the inquiry learning mode corresponds to the receptive learning mode. Taking scientific inquiry as an important way of learning for students will help to fundamentally change the traditional situation of learning leading classroom teaching.

Inquiry is an important and effective way of learning, but it is not the only way of learning. Inquiry learning and receptive learning are not opposites. As long as it is meaningful learning, whether it is inquiry or acceptance, it is an important way to acquire knowledge, but inquiry learning method emphasizes the inquiry process of knowledge and acceptance learning method points to the conclusion of knowledge. Compared with receptive learning, inquiry learning is more discoverable and exploratory, and students are more active. Advocating diversified learning methods based on inquiry is not to exclude other learning methods, but to focus on the current situation of too much emphasis on learning, rote learning and mechanical training. Inquiry learning methods should attract our attention. At present, inquiry teaching should try its best to explore the factors of inquiry from the acceptability of learning, and try its best to guide students to explore by traditional methods such as teaching, asking questions, discussing and experimenting, so as to prepare for complete scientific inquiry learning.

3. Scientific inquiry is an important learning content.

Scientific inquiry is an activity around "problems" and a process of analyzing and solving problems step by step. This problem often corresponds to one or several knowledge topics and belongs to the content of learning itself. More importantly, in the process of scientific inquiry, students can effectively learn the hidden but extremely important learning content-scientific method. The process of inquiry learning itself is the application of many scientific methods. In inquiry learning, students can personally experience the important role of scientific methods in inquiry, learn how to properly apply scientific methods to solve problems and acquire scientific knowledge. Through inquiry learning, hidden scientific method education can be revealed in time, and scientific method learning can be best implemented. As a higher level of learning content, scientific inquiry is the cultivation and improvement of learning ability. The process of scientific inquiry is always linked with solving problems. Students need to collect, analyze and sort out data and apply it to solving problems. The whole process is a process of effectively cultivating students' ability to find problems and comprehensively apply what they have learned to solve problems.

Second, the basic elements of scientific inquiry

The eight elements of the scientific inquiry process summarized in "Senior High School Chemistry Curriculum Standard (Experimental Draft)" are: asking questions, guessing hypotheses, making plans, conducting experiments, collecting evidence, explaining and inducing, reflecting and evaluating, and expressing and communicating.

Third, the basic characteristics of chemistry inquiry learning

1. Problem-centered

Inquiry is a problem-based inquiry, and scientific inquiry learning needs to be carried out around certain scientific problems. The so-called scientific problems are put forward for objects, organisms and events in the objective world. Questions should be related to the scientific concepts that students have learned, and can trigger their activities of conducting experimental research, collecting data and explaining scientific phenomena with data. In other words, questions, as the starting point of scientific inquiry learning, should stimulate students' curiosity and inquiry consciousness, be ideological and inspiring, and make students willing to explore.

2. Emphasize independent participation

To ensure students' independent participation, teachers should respect students' interests and hobbies, encourage students to actively discover and ask questions, and students should form assumptions, conduct experiments and collect evidence according to their attitudes and views on the problem until the problem is solved, instead of strictly following the so-called "only correct" thinking designed by teachers in advance as before. In other words, inquiry learning advocates and ensures that students decide their own inquiry methods and approaches, and teachers only provide necessary help and guidance, and they are not allowed to "intervene". In this way, students can not stick to books, be superstitious about authority, be unconventional and bold in imagination, and have ample opportunities to put forward new ideas, methods and viewpoints through their own thinking. Moreover, in the whole process from asking questions to solving problems, students have the right to evaluate the progress of the learning process and can actively express their views. In this way, the initiative of exploration and research is mastered by students themselves, which embodies students' autonomy and student-oriented everywhere. Teachers' authority is no longer based on students' passive acceptance, but on students' independent participation and promoting students' all-round development.

3. Emphasize practical activities

To carry out and implement research-based learning correctly, we must attach importance to and emphasize practical activities. Inquiry learning does not advocate that teachers tell students ready-made methods and conclusions, but encourages and guides students to discover and explore problems by themselves, provides students with enough opportunities to obtain evidence about problems by themselves, makes students fully engage in inquiry, and attaches importance to students' experience and understanding in the inquiry process and practical activities.

4. Pay attention to cooperation and communication

Research-based learning places special emphasis on cooperation and communication. In inquiry learning, cooperation and communication have two meanings. On the one hand, students are divided into groups and team members cooperate to complete the whole inquiry task. That is, let students explore in groups or teams, teachers delegate power to groups, and members of groups cooperate, discuss and communicate with each other, and are responsible for the inquiry process. In this way, in the process of inquiry, each student undertakes certain tasks, which plays an important role in exploring problems with * * *. Through the cooperation and communication in the group, everyone influences and promotes each other, and everyone can learn effectively, actively participate in inquiry learning activities, and cultivate students' team spirit and cooperative work ability.

Another meaning of cooperative communication in inquiry learning is that each group needs to express the process, activities and results of inquiry clearly in oral and written form after obtaining the results of inquiry within the group, communicate within the group, and explain and defend their own views. In the process of communication between groups, everyone should dare to express their views and be good at listening to others' opinions. Through such discussions and exchanges, students can broaden their horizons, further deepen their comprehensive and profound understanding of the problem, and make the inquiry more rewarding.

(3) Presupposition and generation

Professor Ye Lan said: "The classroom should be a journey in an unknown direction, and unexpected paragraphs and beautiful scenes may be found at any time, instead of a journey in which everything must follow a fixed route without passion.".

Generative teaching is a new concept and strategy advocated by the new curriculum reform. We emphasize the predictability of classroom teaching, and we also emphasize the generative nature of classroom teaching. Teachers should strengthen the exploration of texts and the study of new curriculum ideas, constantly improve their educational wisdom, always pay attention to and timely capture the new information and new problems with exploration value in the classroom interaction between teachers and students, readjust the teaching structure, reorganize the information transmission mode, make the interaction and exploration between teachers and students go to a deeper level, make the classroom produce new thinking collisions and ideological confrontation, and promote the classroom to move from knowledge to wisdom, so as to achieve the purpose of gaining wisdom in understanding and exploration.

Classroom is a dynamic whole of life, which contains contradictions everywhere. The balance and breakthrough between generation and presupposition is an eternal theme. Presupposition and generation are the unity of dialectical opposites, and classroom teaching needs both presupposition and generation. Presupposition and generation are two wings of classroom teaching, which are indispensable.

1. Wonderful generation can't be separated from careful preset.

Everything is established in advance, and it is abolished if it is not foreseen. Presupposition is the basic requirement of teaching, because teaching is a targeted and planned activity. Teachers must have a clear and rational thinking and arrangement of their teaching tasks before class, so they should pay attention to presupposition.

2. Careful preset can't predict all the wonderful generation, teaching is a dynamic generation process, and no matter how careful preset, it can't predict all the details of the whole classroom.

In the actual classroom teaching, it is inevitable that there will be many accidents. Once an "uninvited guest" comes, we should be psychologically prepared and respond flexibly, instead of sticking to the lesson plan before class. Sometimes we can skillfully use the unexpected "substitute", which may become an unexpected and wonderful move in our class!

First, how to preset and generate in the classroom

Professor Ye Lan pointed out: In the teaching process, the dynamic generation of the classroom is emphasized, but teachers and students are not encouraged to start learning in the classroom. Instead, teachers are required to design lesson plans, in which time and space are reserved in advance for students to actively participate and create conditions for the dynamic generation of the teaching process.

1, strengthen the "teaching design" before class

Consciously "expect" the "unexpected" knowledge and wisdom produced in the multilateral dialogue between teachers and students. The state of students in classroom activities includes their learning interests, enthusiasm, attention, learning methods and ways of thinking, cooperation ability and quality, opinions, suggestions, opinions, questions, arguments and even wrong answers. , are generative resources in the teaching process. This requires teachers to pay more attention to ability goals and emotional goals than cognitive goals in teaching design.

2. Teachers should learn to listen.

Students fully express their opinions on textbook knowledge, and each student is constantly enriching himself while listening to others' opinions. Teachers have creative views on students, even "heresy". They should give dialectical evaluation and encouragement, and at the same time express their opinions and correct their prejudices. Promote the teaching process through multi-directional interaction.

Students fully express their opinions on textbook knowledge, and each student is constantly enriching himself while listening to others' opinions. Teachers have creative views on students, even "heresy". They should give dialectical evaluation and encouragement, and at the same time express their opinions and correct their prejudices. Promote the teaching process through multi-directional interaction.

3. Teachers should be "reorganizers" of classroom information.

When students move, it does not mean that teachers have nothing to do, but that teachers should form new and sustained excitement and teaching steps on the basis of collecting and processing this information. Of course, teachers should also seriously consider the views put forward by students and compare them with the expected situation when preparing lessons. If the expected situation occurs, they should teach according to the pre-designed countermeasures. If there is an unexpected situation, we should think about whether it will help students improve their ability. If it helps to improve students' ability, even if it deviates from the original goal, it should follow the students' ideas and produce new "growth points" of problems; If the views put forward by students are worthless or even deviant, this question can't improve students' ability, and teachers can't go with students. Finally, this kind of class needs teachers to strengthen after-class reflection and research.

4. Grasp the generating point of classroom teaching.

Generation point of classroom teaching:

Generate in students' needs-advocate questioning and ask difficult questions; Generated in the activity of trying and exploring; Generated in the multi-interpretation of teaching texts; Generated in the dialogue between teachers and students; Produced in creative activities; Produced in moderate expansion.

(1) High-quality teaching presupposition needs to study teaching materials and students.

On the one hand, teachers should fully understand students' cognitive basis, thinking characteristics and learning psychological state, and preset the teaching process according to students' actual situation. On the other hand, the reality of students is very complicated, and the cognitive basis, thinking characteristics and learning psychological state of different students are very different. Therefore, on the basis of fully understanding students, teachers should preset various channels at the generation point of teaching, so as to make teaching preset more flexible.

(2) The development of teaching process should attach importance to presupposition and generation.

"Teaching is essentially an activity of communication and cooperation." "Without communication, there can be no teaching." The process of teaching development should be the multi-directional exchange and collision of knowledge, thinking, viewpoint and value orientation between teachers and students and between students. First of all, teachers should establish a "student-oriented consciousness" and take cultivating people with sustainable development as the starting point and destination of all teaching activities. While paying attention to the achievement of knowledge and skills goals, we should pay more attention to the achievement of process and method goals, so that students can enhance their thinking ability and problem-solving ability in the process of experience, experience and exploration. When there is a contradiction between teaching generation and presupposition, we should fully respect students, give them the opportunity to express and protect the spark of innovative thinking. Secondly, no matter how full the presupposition is, it is impossible to take into account all the contents produced by teaching. Therefore, teachers should strive to improve their teaching adaptability, cultivate their teaching wit, judge and process all kinds of information generated in the teaching process quickly, flexibly and efficiently, and guide students' thinking.

Second, how to deal with the relationship between presupposition and generation.

(A) based on the preset, improve the quality and level of generation.

First, from the teacher's point of view, we should first study the textbook, read the original intention and new ideas of the textbook, grasp the essence and difficulties of the textbook, internalize the textbook into our own things, have the depth to go in and have the courage to jump out. This is the premise of promoting and capturing valuable generation in the classroom. Secondly, we should broaden our knowledge and enrich our background knowledge. Third, we should study students' psychology and learning psychology.

Second, from the aspect of teaching materials, we should emphasize the basic position and main role of teaching materials. The premise of transcending the textbook comes from the textbook. We must have a comprehensive and accurate understanding of teaching materials, truly understand the original meaning of teaching materials, respect the value orientation of teaching materials, and on this basis, combine students' experience and the development of the times, explore and pursue the extension and expansion of teaching materials, and form students' personalized interpretation.

Thirdly, in teaching, we emphasize careful presupposition, predict and consider the possibility of students' learning activities as much as possible before class, reduce the "generation" of low level and predictability, and stimulate the generation of high level and wonderful.

(2) Oriented to generation, improve the pertinence, openness and variability of preset.

First, we should take the subjectivity of generation as the guide and improve the pertinence of presupposition. Relatively speaking, generation emphasizes students' activities and thinking, and it highlights students' subjectivity; Presupposition emphasizes the design and arrangement of teachers, which embodies the dominant position of teachers.

Second, the randomness of generation (unpredictability) is the forerunner to improve the openness of presupposition. Generation is the "improvisation" of teachers and students, and it is the "beauty that cannot be preserved". It's like an unexpected fantasy. Therefore, presupposition should be flexible and open, leaving room for generation.

Thirdly, it is based on the dynamic nature of generation and improves the variability of presupposition. Emphasizing the dynamic nature of generation means that classroom teaching is not the process of implementing teaching plans, but the process of recreating teaching plans; We should not focus on textbooks, teaching references and teaching plans, but should focus on observing students, listening to students, discovering students and actively interacting with them.

Third, let presupposition and generation serve the development of students.

Presupposition and generation have both unity and opposition. Presupposition attaches importance to and pursues explicit, consequential, and predictable goals, and generates implicit, procedural, individual and unpredictable goals that it attaches importance to and pursues.

Compared with the development of students, presupposition and generation are only means and measures. We must understand and deal with the relationship between the two from the perspective of improving teaching quality and based on the sustainable development of students. In practice, without the development of students, it is impossible to talk about too many presuppositions and too many productions in a class. Even if valuable works affect the preset arrangement, they should not be done hastily. Quality presupposition should not be generated at a low level. In a word, we must look at the relationship between presupposition and generation from the perspective of development. First of all, classroom teaching reform is a negative process, a process from order to disorder and then to order; Secondly, the completion of a certain class teaching task does not affect the all-round development of students. The most important thing in classroom teaching is to cultivate students' autonomous learning ability and innovative quality, which is the fundamental stamina for students' development and teaching development.

(4) Chemical experiment

Experiments in teaching materials:

26 in-class experiments and 7 scientific explorations in Compulsory No.1 Middle School;

Compulsory 2 16 in-class experiments and 6 scientific explorations;

Participated in the experiment in Class 4 14, 6 scientific explorations and 2 practical activities.

(A) the role of chemical experiments

1. Promote thinking and improve ability

2. Stimulate interest and love chemistry

3. Create a good problem scenario

4. Create a harmonious discussion atmosphere

5. The merit lies in the students and the advantage lies in the college entrance examination.

(B) How to improve the use of experiments

1. Develop chemical experiment inquiry-improve students' interest and ability in scientific questions.

A large number of exploratory experiments have been added to the new textbook, so how to make better use of these experiments in teaching? I think it is necessary to increase its inquiry through teaching design, that is, to guide students to ask questions and then explore through experiments. For example, when studying alkali metal-sodium, it can be designed as follows: First, let students discuss and clarify: In general, what aspects can an unknown substance (Na) be studied from? Second, guide students to design their own experimental scheme to study the physical properties of sodium, and then analyze and screen the experimental scheme, and finally form a relatively perfect experimental scheme. Third, carry out experiments, observe phenomena and explain them or ask new questions. During the experiment, the students found two "accidents": sodium can not only be cut by a knife, but also the cutting surface will turn silvery white and darken soon; Sodium not only floats on the water surface, but also reacts violently with water and eventually disappears. This has created new problems. This teaching design well reflects the inquiry of chemical experiments and cultivates students' interest and ability to engage in creative activities in the future.

2. Deal with small family experiments-stimulate students' interest in thinking.

The Analects of Confucius put it well: "Knowing is not as good as being good, and being good is not as good as being happy." Einstein also said that interest is the best teacher. The compilation of the new textbook also pays attention to this point, and it is deeply loved by teachers and students because of its clear and exquisite graphics, beautiful and vivid words and fascinating introduction. Not only that, but also some small family experiments have been added to stimulate students' thinking and interest in learning. At the same time, the new chemistry textbook emphasizes STS curriculum design concept and strengthens the connection between curriculum and social development and scientific and technological achievements. Therefore, it is required to link teaching with production and life, bring students into society, guide students to carry out exploratory experimental activities themselves, and cultivate their pioneering and innovative spirit.

3. Exploring the research nature of chemical experiments-expanding the research topics of chemical knowledge.

When learning the nature of chlorine, let students study the composition of chlorine water through experiments. When designing this experiment, we should first consider whether the chlorine dissolved in water is simply dissolved, or has a chemical reaction, or both. It is also necessary to consider whether there are particles of reactants and products in the system to be tested, so as to judge the products that may be obtained after the substance reacts with water. According to these inferences, the following three experiments were designed. Firstly, the mixed solution of nitric acid and nitric acid was dropped into a test tube containing chlorine water to verify that chlorine water contained Cl-. Secondly, potassium iodide starch was dropped into a test tube containing chlorine water to verify that chlorine water contained Cl2. Third, drop the purple litmus test solution into a test tube filled with chlorine water. According to the fact that the solution turns red, it can be proved that chlorine water contains H+. However, it is suggested that it turns red and then turns pale, indicating that there are still bleachable or strongly oxidizing substances in the solution, thus confirming the existence of sodium hypochlorite. In the process of exploring this experiment, students not only improve their ability to design experiments, but also cultivate divergent creative thinking.

4. Reform the traditional teaching methods-let students really become the main body and participate in experiments.

The traditional teaching method is that teachers demonstrate experiments, and students observe experimental phenomena, analyze and summarize them, and draw conclusions. As a result, teachers often play a one-man show and are in the main position, while students passively accept it and forget it easily, which is not conducive to cultivating students' practical ability and innovation ability. The senior high school chemistry curriculum standard emphasizes that experimental inquiry is an effective learning method, and chemical experiments play an irreplaceable role in cultivating students' observation ability, practice ability and innovation ability.