"Standard" points out that "everyone should learn valuable mathematics ... valuable mathematics should be closely related to students' real life, attractive to them and interesting to them. For example, after knowing the length units of centimeters, decimeters and meters, I left enough time and space for students to measure the length of things around them, their desks and heights, the length and width of classrooms and blackboards, and their parents' waistlines. After learning about Jiao Yuan Powder, let students simulate supermarket shopping activities after class, which not only consolidates what they have learned, but also strengthens cooperation and communication among students. When students learn the knowledge of comparison, they can collect various forms of comparison in real life, which becomes an effective learning resource in classroom teaching and helps students understand the practical significance of comparison in mathematics.

Second, use extension to cultivate students' practical ability.

The content of mathematics is abstract. In the limited teaching time and space, students can't all have the opportunity to practice, but they have more time and opportunities after class. If we can design practical expansion homework in time after learning mathematics related knowledge, we can cultivate students' practical ability. For example, in the teaching of "the size of possibility", you can design a practical problem: make a turntable by yourself and paint it in three colors: red, yellow, green, so that the pointer will occasionally fall in the green area after rotating, and the number of times it falls in the red and yellow areas is similar. How to draw? Try to draw it first, then turn it around a few times to see how it works. This kind of practical work can make students consciously apply their mathematical knowledge to practical work, and students can make personalized designs according to their own ideas.

Third, use extension to lead students into a new mathematical time and space.

Teachers should make use of extension to encourage students to read some reading and thinking activities outside math textbooks such as popular science books and math websites, so as to stimulate their thinking and imitate exercises, which can improve students' interest in learning math and stimulate their curiosity. Providing students with good extracurricular reading materials, subscribing to some mathematics publications, such as "Math Newspaper for Primary School Students", helping and encouraging them to read actively after class can broaden their knowledge horizons and improve their ability to acquire knowledge independently. Students can also write about math diary and math diary, which is a true portrayal of students using mathematical knowledge to solve practical problems in their daily life. Let students write it down through essays or diaries, which can deepen students' understanding of mathematics knowledge, close the connection between mathematics and real life, and improve students' ability to apply what they have learned. Through math diary, students, parents and teachers have a good interaction, and children can also express what they dare not say in their diaries and learn more from each other. Carry out small mathematical investigation activities, let students carry out social practice, promote students' interest in learning, enhance students' activity ability and broaden their horizons.

Problems that should be paid attention to in the development of primary school mathematics curriculum;

Improper timing and excessive expansion will often bring bad results, so we should pay attention to the following issues:

First, the content of expanding and extending activities should be appropriate.

There is too little content to expand and extend activities, and the effect is not great. If there are too many, it will usurp the role of master. Appropriate measurement needs to be based on teaching objectives and students' cognitive needs. Every activity has a clear goal, and outreach activities serve to achieve teaching goals. Excessive expansion activities will increase students' learning burden and weaken their interest in learning.

Second, the difficulty of expanding the content of extension activities should be appropriate.

Expansion and extension must be carried out according to the characteristics of mathematics subject, students' age characteristics, cognitive characteristics and knowledge and experience. Don't neglect students' understanding because of the need to expand and extend. Teachers need to analyze all kinds of supplementary teaching materials according to the teaching objectives, delete and supplement valuable resources from multiple angles and levels, and better help students build a good cognitive structure.

Third, we can't ignore the teaching material system in expanding the content of activities.

Many teachers often presuppose the extension of teaching when designing teaching, especially in the study of new courses. But some teachers only consider the problem from the perspective of teaching. In order to complete the preset teaching process, they ignore the students' subjective participation, students' active exploration and teaching material system. Every math class has a learning theme. Teachers always set teaching objectives for each class according to students' learning foundation and related knowledge and experience. However, many teachers' teaching extension activities ignore the teaching focus, deviate from the learning theme, deviate from the teaching materials, and are a little overwhelmed, which has become ineffective labor. To expand the content of outreach activities, we should fully establish the concept of teaching materials, analyze the whole primary school mathematics teaching content as a whole, systematically cultivate students' purposeful and hierarchical methods of learning mathematics, and cultivate students' ability of inquiry and cooperation in mathematics.

The expansion of mathematics learning has opened a window to the world for our mathematics classroom, allowing students to acquire information, integrate information, enrich knowledge, feel thoughts, create thinking and improve learning quality in a broader mathematics world. Valuable extracurricular extension activities are an effective supplement to classroom mathematics learning, as long as we carefully interpret the teaching materials, objectively analyze the learning situation, effectively extend classroom teaching, overcome randomness and blindness, improve pertinence and effectiveness, and highlight autonomy and innovation. It can stimulate students' enthusiasm for research, and at the same time make students form good habits of using mathematics and doing mathematics. Only by paying attention to the extension and expansion of knowledge can students better explore, consolidate and improve, and their innovative consciousness and ability can be effectively cultivated.