Under the background of the new curriculum reform, it is necessary to cultivate students' innovative thinking and let them explore the calculation method of circular area independently, but in the end, the calculation formula of circular area should be deduced by cutting the cake. First of all, this is because the "cake-cutting" method is the crystallization of the wisdom of the ancients, and it is a recognized and adopted method in deriving the formula for calculating the area of a circle. After all, our learning is mainly based on indirect experience, and learning is carried out on the shoulders of our predecessors. Secondly, the "cake cutting" method is based on the calculation formula of parallelogram and triangle area. At this time, students already have the idea of "transformation", and "cutting cakes" is the further sublimation and application of the idea of "transformation". This method is easy for students to understand, logical and convincing. In addition, the method of "cutting cake" embodies the transformation idea from whole to part and then to whole. Students can intuitively observe that the area of the circle before transformation is equal to the area of the parallelogram after transformation. 2. The base of parallelogram is half of the circumference. 3. The height of parallelogram is the radius of circle. When students see this, they can get the formula of circular area through the deformed parallelogram formula, which can be said to be well-founded, in line with the characteristics of human thinking and rigorous and scientific mathematics.