片断一:在操作中感悟(教师引导学生看一看、摸一摸自己课前制作的长方体学具的上、下、前、后、左、右六个面)师:刚才大家摸到长方体的六个面的总面积就是长方体的表面积。怎样求长方体的表面积呢?下面请同学们把学具平放在桌子上展开各面看一看,想一想怎样求,想好的同学请上台 Piece one: perception in the operation (teachers guide the students to take a look at the touch of their own class before the rectangular body made of the upper, lower, front, rear, left and right six face) Teacher: Just now you touch the box The total area of ​​the six faces is the cuboid surface area. How to look for the surface area of ​​the cuboid? Now ask the students to flat lay the table on the table to look at each other, think about how to ask, think good classmate on stage