教学有法,教无定法,贵在得法.教育学家杜威曾说:“数学绝对不仅仅是简单地告诉,教学应该是一种过程的经历,一种体验,一种感悟.”数学教学中,教师应立足教材,构建有效情境,向学生展示数学本质,使学生理解概念的逐步形成,真正使学生的学习过程成为在教师引导下的再创造过程.笔者认为教师应该格外关注课堂教学中的“教学起点”问题,找准教学起点,恰当设疑提问,方能使课堂教学更有效.本文结合随机事件的概率略抒浅见,希望起到抛砖引玉的作用. Dewey, an educator, once said: “Mathematics definitely does more than simply tell that teaching should be a process experience, an experience, a perception.” Mathematics Teaching, teachers should be based on textbooks, to build effective situations, to show students the nature of mathematics, so that students understand the gradual formation of the concept, the real learning process to become teachers under the guidance of the re-creation process. In the “teaching starting point ”, identify the starting point for teaching, proper questioning, in order to make the classroom teaching more effective.This paper combined with the probability of random events to express my views, hoping to play a valuable role.