Teaching Primary Mathematics "area Of ​​a Circle.

The knowledge of "the area of a circle" is not only an important part of geometry education in elementary school, but also essential content of basic mathematics education in most countries. In mathematics curriculum,"the area of a circle" is in the second segment, i.e., the graphics and geometric, of which teaching objectives include understanding the fixed value of the ratio of the circumference of circle with diameter through the operation, mastering the circle circumference formula and the area of a circle formula, and can solve simple practical problems. Meanwhile, the knowledge of the area of a circle is the basic of learning the surface area and volume of cylindrical and cone. Therefore, teaching and research on the area of a circle has always been a front-line teachers and teaching researchers’attention. Throughout the current research of the area of a circle, there are quite a few papers about the instructional design of this lesson, teaching reflection and evaluation. However, they lack comprehensive research review.In fact, according to the comparison of students before and after the course, the author speculates that the majority of students have a certain understanding on the "circle", but few knows the concept and the essential attribute of circle. They have much better grasp of the straight edge graphics area, but this knowledge has negative effect on understanding circle. For the question that what factors determines the area of a circle, the tested students write six different answers, reflecting the their obscure on this problem. Besides, front-line teachers also have difficulties on how to guide students to understand curl as straight, and on penetration of the ultimate thought. In the face of these problems, we need more in-depth study and reflection.To solve the above problem, the author try to take of approach of-access to relevant literature, teaching status survey-determine the research direction-comparative analysis of textbooks-instructional design-appreciation proposed teaching suggestions-proposed teaching suggestions. From the angle of the area of a circle upper depth analysis of the mathematical knowledge-student learning before and after the measurement of the area of a circle-the various versions of the compilation of teaching materials structure-excerpt outstanding teaching Appreciating, sort out the crux of the problem, for teachers to learn the various versions of textbooks and instructional design advantages for students to create a wider space for thinking, and promote the construction of elementary school mathematics textbooks and effective teaching to provide a basis for better carry out teaching and research.