《认识周长》这节课是在学生认识三角形、平行四边形、长方形、正方形等平面图形的基础上展开的,这是学习平面图形周长的基础。学生只有对周长的概念做到真正的理解,形成表象,才能对后面的周长的计算、测量及应用有更好的理解。以下谈谈课后对本节课的一些反思:一、有效前置性学习学生对于周长的理解,难就难在“周长”的概念的理解上,怎样才能在课前引导学生去认识周长这个概念呢?“平面图形一周边线的长就是它的周长。”这句中“一周边线”是个难点,于是在学 The lesson “Perception of Perimeter” is based on students’ understanding of plane graphics such as triangles, parallelograms, rectangles, and squares. It is the basis for learning the perimeter of graphic graphics. Students only have a true understanding of the concept of perimeter, the formation of appearance, in order to calculate the circumference of the circumference, measurement and application of a better understanding. The following talk about some of the lesson after class reflection: First, the effective learning of the perpetuity of students, it is difficult in the understanding of the concept of “perimeter”, how to guide students before class to go Perception of the concept of perimeter? “” The length of the perimeter of a graphic plane is its perimeter. “The phrase” perimeter line "is a dilemma so learning