一、科学性和针对性 设疑,首先要明确问题的来源,能针对学生普遍存在的困惑与知识缺陷,一举中的。同时,有针对性的设疑一定要以科学性为前提,不能为了突破难点而不顾及问题的科学性。比如在一次“质量守恒定律”的公开教学中,教师在提出“化学反应前后,参加反应的各物质的质量总和是否等于反 First, the scientific nature and pertinence Questioning, we must first clarify the source of the problem, can address students’ pervasive confusion and knowledge defects, in one fell swoop. At the same time, targeted suspicions must be based on science, and they must not take into account the scientific nature of the problem in order to break through difficulties. For example, in an open teaching of the “law of conservation of mass,” the teacher asks whether the total mass of each substance participating in the reaction is equal to that before and after the chemical reaction.