情景再现:“桃树和梨树共有100棵,桃树和梨树棵数比是7∶3,桃树和梨树各有多少棵?”学生课前已经预习过课本,无一例外地进行了如下解答:7+3=10 100×7/10=70(棵)100×3/10=30(棵)。我问:“还有不同的方法吗?”一阵沉默。预想中的多种方法因为学生的预习而没有如期出现,怎么办?出示其他方法?还是留时间给学生,让学生发 Scene reproduction: “There are 100 peaches and pear trees, peach and pear number ratio is 7: 3, the number of peach trees and pear trees?” “Students have previewed the textbook before class, without exception To the following answer: 7 +3 = 10 100 × 7/10 = 70 (tree) 100 × 3/10 = 30 (tree). I asked: ”Is there any other way?“ ”Silence. What to expect? Many ways to anticipate a student’s prep and not to appear on schedule, what to do? To show other methods? Or to leave time for the students, let the students hair