“长方体和正方体”单元知识的教学,是使学生由面的认识到体的认识的飞跃,是培养学生三维空间观念和想象能力的开始,也是学生学习其它立体图形知识的基础。数学中应充分运用直观手段,帮助学生掌握基础知识。培养学生逐步形成正确的空间观念。一、“长方体和正方体认识”的教学(一)长方体的引入。长方体的概念是通过例举实物引出的,并未给出其定义。教学时,例举的实物应充分接近长方体,以突出其本质属性,形成正确的概念。学生举例时,教师应随 The teaching of “cuboid and cube” unit knowledge is to enable students to realize the leap of understanding of the body from the surface, is the beginning of cultivating students’ three-dimensional space concept and imagination ability, and also is the basis for students to learn other stereoscopic graphic knowledge. Mathematics should make full use of visual means to help students master the basics. Cultivate students to gradually form the correct concept of space. First, “Cuboid and square understanding ” teaching (a) the introduction of the cuboid. The concept of a cuboid is derived by way of example and does not give its definition. When teaching, the examples should be sufficiently close to the cuboid to highlight its essential attributes and form the correct concept. When students give examples, teachers should follow