一、条件不变,问题改变对例题的问题进行拓展、引伸,得到一系列有一定深度的问题,然后引导学生深入思考,发散思维。例1 两地相距270米。小东和小英同时从两地出发,相对走来。小东每分钟走50米,小英每分钟走40米。经过几分钟两人相遇? 学生利用“共同走的路程÷速度和”解决这一问题后,教师可出示下列问题: First, the conditions remain unchanged, the problem changes on the sample questions to expand, extension, get a series of questions with a certain depth, and then guide students to think in depth, divergent thinking. Example 1 270 meters apart from each other. Small East and small British departure from both at the same time, relative to come. Small East walk 50 meters per minute, small British walking 40 meters per minute. After a couple of minutes, the two meet each other. After students solve the problem by using the “distance traveled together and speed”, the teacher may show the following questions: