一直以来,教师教学“用分数表示可能性的大小”的一般流程是:先教学猜一次、摸到一个球或一张牌的可能性,然后再迁移至摸到一类牌、一类球以及一类数的可能性。这样的教学,固然能体现循序渐进的原则,但由于缺乏一个整体布局和 The general process that teachers have been teaching “using the fraction to indicate the size of the possibility ” has always been to first guess the probability of touching a ball or a card, and then move to touch a card, a class Balls and the possibility of a class number. Although such teaching can reflect the principle of gradual and orderly progress, due to the lack of an overall layout and