一、教材简析本单元的教学是在学生已经初步掌握了长方形和正方形的特征和周长、面积计算的基础上进行的。由于线和角是构成几何图形的基本元素,垂直和平行是认识几何图形特征的基本概念,所以本单元的教学又是学生进一步学习三角形、平行四边形 First, the textbook analysis The unit of teaching is that students have initially mastered the characteristics of rectangular and square and perimeter, area calculations based on. Since lines and corners are the basic elements that make up the geometry, vertical and parallel are the basic concepts for understanding geometry features, so the unit's teaching is about students further learning about triangles, parallelograms