【课题研究前】出示两个平行四边形,怎样比较它们的大小?出示方格纸,请学生利用方格纸数出平行四边形的面积。师:数方格求面积的方法很麻烦,有局限性,你能有更好的方法吗?生(无语)师:可以将平行四边形转化成我们学过的什么图形?生:长方形。为学生提供学具:平行四边形硬纸片、手工剪刀,请学生按照教材中的剪法动手剪一剪。 [Pre-Research] Present two parallelograms, how do they be compared? Show the squared paper and ask the students to use the squared paper to find the area of ​​the parallelogram. Teacher: How to find the area of ​​squares is very troublesome, there are limitations, you can have a better way? Health (speechless) Teacher: What can we convert the parallelogram into what we have learned? Provide students with learning tools: parallelogram cardboard, hand-scissors, please students in accordance with the teaching materials in the scissors cut.