课前预习是听课之前主动了解将要学习内容,为听课做准备。它能使学生发现旧知中的薄弱环节和新知中的疑难问题,而带着疑问去听课将收到意想不到的效果。预习对于高年级或已有经验的学生来说并不难,他们知道预习该干什么。但对于低年级学生来说,确实有点难度,需要教师对其不断进行培养。为了达到预习的目的,帮助学生形成预习的经验,为课堂教学提供有力的帮助,教学时可以这样设计: Pre-class preview is to take the initiative to understand before the lecture to be learning content, to prepare for lectures. It enables students to discover weaknesses in old knowledge and problems in new knowledge, and taking questions with them will result in unexpected results. Previewing is not difficult for advanced or experienced students who know what to expect. But for the junior students, it is a bit difficult, need teachers to continue its training. In order to achieve the purpose of preview, to help students form a preview of the experience for the classroom teaching to provide effective help, teaching can be designed as follows: