一、经验再现,突出“转化”的数学思想 师:你能完整地说出平行四边形面积的计算公式吗? 生:s=ah(板书公式) 师:这个公式是怎样推导出来的?(学生回答后,多媒体演示将平行四边形割补转化为长方形的过程) 师:通过割补的方法将平行四边形转化成我们学过的图形,推导出了求平行四边形面积的计算公式,在这个过程中我们运用了一个很重要的数学思想“转 First, the experience of reproduction, highlighting the “conversion” of mathematical thinker: Can you completely tell the formula of the parallelogram area? Health: s = ah (Formulation) Teacher: How is this formula derived? After the multimedia demonstration of the parallelogram cut into rectangular process) division: the method of cut through the parallelogram into the graphics we have learned, derived the formula for calculating the area of ​​the parallelogram, in the process we use A very important mathematical thinking "turn