【教学设计思路】通过复习提问及演示实验,创设问题情景,使学生对所研究的问题产生兴趣.在教师的引导下,利用控制变量的思想对所提出的问题展开研究,同时引导学生以小组为单位开展自主合作学习,积极参与探究活动,学生在经历了提出问题———形成猜想———制定计划与 [Teaching Design Ideas] Through reviewing questions and demonstrating experiments, creating problem scenarios to enable students to become interested in the research questions. Under the guidance of teachers, use the idea of ​​control variables to conduct research on the issues raised, and guide students to the group. For the unit to carry out independent cooperative learning, and actively participate in inquiry activities, students have experienced the problem of making a conjecture --- formulating a plan -- and