Abstract: With the gradual advancement of basic education curriculum reform, classroom teaching is undergoing substantial changes. The classroom is open, teaching is generated, and the teaching process is the dynamic generation of static presupposition in the classroom. Teachers should respect students' individual differences, students' unique feelings and experiences, and pay attention to the generation of dynamics and human feelings. Generation is not a denial of presupposition, but a challenge to presupposition. Wonderful generation comes from high-quality preset. Only by careful presupposition before class can we skillfully use presupposition, integrate presupposition and even give up presupposition in class, so as to obtain and generate, let the light of wisdom shine in class and interpret wonderful classroom.

Keywords: effective preset generation

The highest purpose and core idea of the new curriculum is that everything is for the development of every student, and development is a dynamic generation process. On the one hand, teachers' teaching design before class, that is, presupposition; On the one hand, it is the occurrence, development and change of the actual teaching process, that is, the generation. With the deepening of curriculum reform, the two opposing concepts of presupposition and generation have been integrated into our teaching practice. Many teachers always find it difficult to deal with: more subjective presuppositions and less dynamic generation; Dynamic generation is much more, and subjective preset is useless. How to deal with the relationship between presupposition and generation, so that presupposition and generation can dance together? The Mathematics Curriculum Standard points out that teaching is a contradictory unity of presupposition and generation, and closed and open. Therefore, under the background of new curriculum, effectively grasping the relationship between presupposition and generation is the key to improve classroom teaching efficiency.

First, carefully preset and generated at any time.

The more detailed the teacher's presupposition and consideration, the more targeted the teaching can be, and the broader stage can be provided for instant generation. Predicting learning situation, constructing flexible teaching scheme and effectively developing curriculum resources are the key points of teaching presupposition and the logical starting point of dynamic generation. 1. The presupposition before class is to comprehensively analyze the learning situation and generate rational knowledge.

Mathematics curriculum standards point out that mathematics teaching activities must be based on students' cognitive development level and existing knowledge and experience, and students' mathematics learning activities are a process of self-construction and self-generation under the guidance of teachers. The generation of teaching behavior is determined by the age characteristics, personality characteristics, knowledge and experience of our educational objects and the complexity and diversity of living environment. Judging from the teaching process, teaching is a process of interaction between teachers and students, and students' original knowledge and experience, ability level and personality characteristics will inevitably affect the development and promotion of mathematics activities. Therefore, it is an important prerequisite for scientific presupposition to understand students as much as possible and predict their learning behavior, learning methods and problem-solving strategies. Facing our students, when preparing lessons, we may wish to consider the following aspects: ① What is the starting point of students' study? ② In the process of learning, what are students more interested in? ③ What is the distance between old knowledge and new knowledge? Do you need to give some hints to the students? Will these hints reduce students' thinking intensity? ④ What questions may students ask? What are the possible answers to the students' questions? ⑤ What can you learn by self-study? What do you need to discuss with each other? What content needs the teacher's guidance and guidance is what the teacher needs to fully understand by default. Because only by working hard on presupposition and rationally understanding generation can we better solve the problem of classroom generation.

For example, in order to better understand the starting point of students' learning, I conducted a survey of students in my class before teaching the second volume of the second grade of primary school mathematics by People's Education Press, and found that students have obtained perceptual knowledge of numbers within 10,000 through various channels in their lives. Most students can read and write some numbers within 10 thousand, but there is no specific and complete reading method. Obviously, the realistic starting point of students is much higher than the logical starting point of textbooks. Based on this reality, I reoriented the teaching objectives and focus of this class, from the original reading method of mastering numbers within 10 thousand under the guidance of teachers to the reading method of self-discovery and generalization. And creatively adjusted and supplemented the teaching materials. In practical teaching, I let students count and read by themselves with learning tools to form learning materials; Then, in the way of group cooperative learning, these figures are classified and summarized to find a summary reading method. It is precisely because of grasping the realistic starting point of students' learning that teachers can truly safeguard students' dominant position without binding students with subjective will; Give students room for full development, don't do everything instead, and let group cooperation achieve full and effective results. The whole teaching process makes students feel that they can do whatever they want and achieve something. In the group report exchange, students are in high spirits, and the class is full of climax and excitement. The students' true voice fully shows that they are the most active, active in thinking, sensitive in feeling and sincere in understanding problems. In the face of students' diversified and personalized answers, teachers can only keep calm in the face of difficulties and improve classroom teaching efficiency if they fully predict. 2. Construct flexible lesson plans to promote timely generation.

In teaching, presupposition is necessary, because teaching is a purposeful and planned activity, and teachers must have a clear and rational thinking and arrangement of their teaching tasks before class, but at the same time, this presupposition is flexible and has a blank presupposition. However, in the traditional presupposition, in order to pursue the perfection of the classroom, the teacher will even design every sentence to be said in the classroom, and no complications will be allowed in the classroom process. In such a class, teachers seldom listen to students' real thoughts attentively and patiently, but drag students' answers into the preset answers blindly. The reason for this phenomenon is that teachers construct a linear teaching plan when preparing lessons, ignoring that classroom teaching should be a dynamic and complicated process. Therefore, the default value should be flexible and should be left blank appropriately. For example, in the first class of "Understanding Perimeter" in the third grade, there is a link to measure the perimeter of leaves. In this part of teaching, teachers should not presuppose a unified measurement method, but should give full play to students' creativity and give them enough space to explore the measurement methods themselves. In this design, students can spread the wings of imagination and produce sparks to show their wisdom.

Second, it is dynamically generated and has no default value.

The development of teaching activities sometimes coincides with teaching presupposition, but more often it is different or even completely different from presupposition. When implementing presupposition, don't stick to presupposition, but deal with the relationship between presupposition and generation wisely, so that generation will be more exciting. 1, flexibly select generation preset.

Before class, teachers preset teaching plans in multiple dimensions, which provides a broad space for the dynamic generation of classroom teaching. For example, in the preset "Preliminary Understanding of Fractions" scheme, I prepared some learning tools (such as rectangular, square, circular, triangular and other pieces of paper and line segments) to ask students what scores they want to know on the basis of knowing 1/2. Some students want to know 1/3, some students want to know 1/4, and some students want to know. Now, please use the learning tool in your hand, fold it up and color it to create the score you want to know. Because the presupposition is completely reasonable, students quickly show their creative achievements.

By choosing presupposition correctly and allowing students to create and generate flexibly, students not only successfully construct the meaning of knowledge, but also go through the problem-solving process of discovering problems, putting forward conjectures, verifying conjectures and forming conclusions, thus enhancing their awareness and ability of self-inquiry. 2. Ingeniously integrate the preset in the generation process.

The teacher's way of thinking is analytical when teaching presupposes. However, in the teaching process, teachers should face the real teaching directly and integrate various presuppositions before class according to the specific process of teacher-student interaction. At this time, teachers' thinking is more integrated. We should adjust our teaching objectives, teaching methods, teaching contents and activity plans in time according to the new problems and obstacles encountered by students in the classroom, the atmosphere of the classroom and the progress of teaching, and make a secondary design of paperless teaching in our minds.

For example, when using letters to represent numbers in teaching, teachers' teaching presupposition originally follows two examples provided by textbooks, and gradually guides students to understand and learn to use letters to represent numbers in specific situations. Then use letters to represent numbers to consolidate knowledge. Obviously, this presupposition only considers students' knowledge reserves before class, ignoring students' experience accumulation in doing mathematics in class. In actual teaching, it is possible for students to jump out of the preset before class, instead of understanding knowledge first and then applying it, they should apply knowledge first and then understanding it. If teachers also mechanically bring students into their own preset track, then students' enthusiasm for learning will be affected. At this time, teachers can tactfully integrate preset learning activities, take the initiative to let students play the leading role in front of the stage, and adapt topics in practice. At the beginning of the class, students can write formulas. According to the existing learning experience and migration ability, students will soon understand that formulas containing letters can not only represent numbers, but also represent quantitative relations. Then I asked two questions: What have you learned about using letters to represent numbers? What else do you want to know? Make the students who succeed for the first time have new confusion and set off the enthusiasm for re-exploration. Through questioning and communication, students at different levels can learn from each other, learn from each other's strong points and get different development, so that the original mechanical teaching presupposition becomes full of spirituality, wisdom and vitality in the co-creation of teachers and students. 3. Decisively abandon the presupposition in the generation.

Because of the openness of teaching under the background of new curriculum, students often put forward some unexpected ideas. Faced with the content beyond these presuppositions, if teachers can give full play to their educational tact, break through the original teaching presuppositions, capture the meaningful components in the temporary generation resources, give up the preset lesson plans in time, and generate new lesson plans according to the students' creation, they will often achieve unexpected results.

Take the number of squares as an example. This lesson is preset before class. On the basis of learning the multiplication formula of 1-5, the multiplication formula of 6 is compiled. At the beginning of the class, I showed the students the grid diagram in the textbook (there are 6 squares in each row and 9 rows in * * *) and asked them to form a multiplication formula of 6 according to the grid diagram. The students finished it quickly, and then something unexpected happened. A classmate said: he has a way to make students make up the multiplication formula of 7. I asked him: What can you do? He replied, I draw another row of nine squares on the grid, so there are seven in each row. I affirmed the students' diligent thinking and got rid of the preset teaching plan. Then he drew a row of squares in red ink on the square map and asked the students: Can you try to make up the multiplication formula of 7? The students replied in unison: Yes. Then the students actively knit on the paper.

In the above-mentioned teaching process, when the students' self-selected learning content deviated from the teacher's pre-class preset, I gave up the preset decisively to satisfy the students' desire for inquiry and received unexpected results. The teaching tasks completed in two classes are completed in one class, and students' cognitive needs are also activated. In the open and interactive teaching situation, students often sprout many ideas and have inspiration and epiphany. Some are reasonable, some are unreasonable. Teachers' clever grasp and application of teaching can not only broaden students' learning content and thinking space, but also reflect that students' mathematics learning activities are a positive construction process.

Third, the continuation of future generations.

After-class exercises are an important continuation of classroom learning. A good math class does not lie in its order, fluency or wonderful generation, but in whether it really integrates knowledge into children's thinking and guides practice. Our practical design lies in whether students can make full use of their own ability organs and generate their own theoretical knowledge in the process of interaction and activities.

There is no best, only better, and teaching is always an art of regret. Each lesson is a comprehensive generation process of unrepeatable passion and wisdom. Presupposition and generation are not completely separated, but complement each other. Presupposition and generation serve students to learn knowledge and improve their ability. Therefore, let's reflect the ingenuity of teachers in the preset, show the spark of wisdom interaction between teachers and students in the generation, and pursue the generation of foresight before class, the dynamic generation of classroom teaching and the wonderful generation of after-class development. Promote students' all-round, sustained and harmonious development.

2. "New Curriculum Concept and Primary School Mathematics Curriculum Reform"

3. Mathematics Curriculum Standards for Full-time Compulsory Education (Experimental Draft) 4. Rejuvenate the vitality of mathematics classroom in the fusion of presupposition and generation.