在自然课的教学过程中 ,教师要精心地选择和设计学具 ,这对师生顺利完成教学任务、达到教学目的起着非常重要的作用。好的学具除了要具备实用、美观、安全等方面的特点外 ,还应该具有以下特点 :一、学具应该是有结构的所谓“有结构”,是指学具中隐含着规律或现象 ,而这些规律或 In the course of teaching nature, teachers should carefully select and design learning tools, which is very important for teachers and students to complete the task of teaching and achieve the purpose of teaching. A good learning instrument should have the following characteristics in addition to being practical, beautiful and safe. First, the learning instrument should be structured with the so-called “structured” meaning that the rules and phenomena are implicit in the learning instrument And these rules or