Teaching has the law, but teaching cannot. There are various teaching methods, so is the introduction of new courses. Because of different teaching contents and different teaching objects, teachers have to design flexible, vivid and interesting lead-in to make classroom teaching lively and full of vitality.
First, experimental methods.
Chemistry is an experimental science. At the beginning of the new class, if we can skillfully arrange an experiment with novel phenomena and vivid descriptions, it will arouse students' strong interest in understanding and stimulate their strong thirst for knowledge. Then, teachers can seize this best opportunity to guide students to understand the essence of things through phenomena and make chemistry class fascinating and lively.
(1) Introducing new courses with interesting experiments
"Interest is the emotional expression of people's cognitive needs and the cognitive tendency to actively explore something." Taking this as an opportunity, students' learning can be deeply introduced. For example, when talking about "combustion and slow oxidation", students are arranged to watch an interesting experiment of "making a fire in water": oxygen comes into contact with white phosphorus immersed in hot water through a glass tube, and as a result, white phosphorus actually burns in water, resulting in a miracle of "compatibility between water and fire". This magical experiment makes students feel incredible, and their enthusiasm for exploring problems is very high, thus laying a good foundation for the explanation of combustion conditions.
(2) Create "contradictory" experiments and introduce new courses.
Teaching practice shows that it is difficult to attract students' attention and interest by introducing new courses without any contradictions and conflicts. In the introduction of the new curriculum, if some "contradictory" experiments are designed, the situation of cognitive conflict will constitute suspense, that is, students are eager to solve a certain problem, but they can't solve it with what they have learned. In this atmosphere, students' attention is the most concentrated and their thinking is the most active, so the effect of teaching new courses is naturally good. For example, in the teaching of "molecules", the teacher quietly wrote "1+ 1≠2" on the blackboard at first. At this time, students were confused, which immediately aroused their "curiosity" and formed a cognitive conflict. Then, the teacher demonstrated the experiment: 50 ml of alcohol and 50 ml of water were mixed. After observation, students found that the total volume was not equal to 100 ml. However, the demonstration results of this "contradictory" experiment did not lift the suspense, and even made the students "angry". At this time, the teacher pointed out: "If you want to understand why, you must understand molecules." The "contradiction" experiment creates a scene of cognitive "conflict", and with appropriate questions, it quickly arouses students' strong desire and demand for new knowledge.
Second, the story method
Stories have a special appeal to people. Young students are full of curiosity, thirst for knowledge and imagination. They prefer fascinating stories. At the beginning of the class, we can use stories and legends related to the teaching content to make it quiet quickly, which can also cause suspense and timely transfer students' unintentional attention to intentional attention, so as to achieve the purpose of introducing new lessons. For example, in the class of "methane", the teacher said, "Tell a story first today." The whole class was silent. "/kloc-in the summer of 0/928, while the warlords were in melee, one of the commanders under warlord Xu turned his greedy eyes to the rich and luxurious tomb of Cixi in Dongling, hoping to make a windfall. When the tomb was opened, the first thing they saw was an exquisite cigarette case containing fine opium. At this time, an officer was addicted to cigarettes, and he pulled out a match and wanted to smoke a few mouthfuls. It was just a small fire and the grave happened. Later, it was found through investigation that the explosion was caused by a gas called methane. Where is the methane? We will learn some of its properties in this class. " This almost bizarre story surprised the students, who immediately became extremely curious about methane and consciously entered the role of learning. The introduction of new courses in this way not only creates suspense for students, but also makes them have a strong interest and curiosity in learning, which lays a good foundation for theme teaching and embodies the advantages and advantages of story introduction.
Third, the observation method
This new lesson introduction is to provide students with perceptual materials related to teaching through visual teaching AIDS such as objects, models and wall charts, and lead to the theme of the new lesson intuitively and vividly. For example, the "molecule" section in the introduction of new courses can be observed. In class, the teacher first shows a wall chart with photos of molecules to guide students to observe carefully, so that students can have a perceptual understanding of the nature of "molecules are real" and "there are gaps between molecules". For another example, at the beginning of the new class, the teacher shows a bottle of turbid river water, tap water and distilled water in turn, which can be quickly and naturally introduced into the teaching of "water purification". Similarly, showing a "sword" as "iron" and projecting diamonds and graphite into "several simple substances of carbon" can all play a very good role, and many contents in junior middle school chemistry can be introduced in this way.
Fourth, review the past and learn new methods
Confucius said: "Review the past and learn the new", and Pavlov also pointed out: "Any new problem is solved by using the existing old tools in the subjective experience." In other words, all kinds of new knowledge are developed from old knowledge. "Reviewing the past and learning the new" is also a common method in chemistry classroom teaching.
For example, when talking about "laboratory preparation of carbon dioxide", the teacher first guides the students to review the drugs, devices, steps and operation points in the laboratory preparation of O2 and H2, and then "learn new things" on the basis of "reviewing the past". Similarly, we can introduce "universality of alkali" by reviewing "universality of acid" and introduce the teaching of atoms by recalling the properties of molecules. It is worth noting that in the process of reviewing the past, "reviewing the past" serves to "know the new" and must not be reversed.