? The basic nature of comparison taught by Mr. Sun is an operable and regular concept teaching, not a typical "boring" concept. Judging from this attribute, the teaching of this kind of concept class has both exciting "content to talk about" and "careless trap" Teachers often pay too much attention to the operational content and laws in the concept, which leads to extremes in the classroom and blindly pursues the training of methods, while ignoring the profound understanding of the concept itself. By observing the basic nature of Bi, Mr. Sun has well implemented the teaching objectives of the concept class, put pen and ink on the formation process of the concept and students' learning path, and constructed a link with the "invariance of quotient" to catalyze students to transfer knowledge vertically, thus completing the learning closed loop of "problem-driven-knowledge transfer-problem-solving-law unification", which is solid and efficient. At the same time, in the lead-in session, teachers let students completely immerse themselves in the problem-driven situational learning through the "big situation" of campus culture-gaining momentum (situational lead-in), rushing (reviewing old knowledge), splashing (exploring new knowledge), surging (consolidating exercises), gathering (summing up in class) and "small situation" with strong sense of substitution-"Which cup of sugar water is the sweetest?
? Suggestion: The situation of sugar water problem is very clever and can be further developed. After the students learned the basic nature of proportion, the design question was: "When you pour two cups of sugar water into the same empty cup, does the sweetness change?" Can you explain the truth from a mathematical point of view? " Through the setting of core questions, the driving source is generated, which causes students to think deeply and extend concepts, and finally achieves the purpose of learning, understanding and applying concepts.
? Teacher Ding's understanding of percentage also focuses on the formation process of a new conceptual form-expression number. We say that the concept is boring because it expresses a result, a highly generalized knowledge after reasoning and verification, so students will have a "high threshold" in contact, understanding and application. Teacher Ding moved the starting point of teaching forward and guided students to integrate exploration, conjecture and experience in the process of solving problems, so that the concept of "percentage" came naturally. On the other hand, the design of this module embodies the immersion teaching strategy driven by core problems and taking situation setting and problem solving as the learning path. In the two steps of "discrimination" and "number-choosing thinking", the percentage obtained from life will return to life, "200% means overfulfilling" and "alcohol degree selection", which not only endow students with the ability to perceive mathematical concepts, but also cultivate and enhance their diversified knowledge and experience (multidisciplinary knowledge, common knowledge, daily knowledge, etc.). ).
? Suggestion: For "overfulfilled", it is the extension point of the concept of "percentage". Students will have some understanding conflicts when they know the false scores in the next textbook of grade five. At this time, the percentage greater than 1 can be associated with the false score greater than 1, and the knowledge can be interconnected with the life attribute with more prominent percentage.
? Six dimensions of understanding-"explanation, interpretation, application, insight, empathy and self-knowledge." This central group training, two classes have brought us a lot of inspiration. Whether it is concept teaching, calculation, graphics or method teaching, we should pay great attention to "understanding meaning and realizing transfer" as the teaching goal, avoid simply covering the content of teaching materials, and start with the tail to improve students' learning effectiveness.