函数图象变换问题,学生常将左移和右移相混,伸长和缩短互淆.究其原因,与我们的教材是不无关系的.依据现行教材,函数图象变换问题的教学一般是按以下“三步曲”进行的:Ⅰ作出用于对比的两个函数的图象C_1和C_2,再观察分析它们的位置关系进而得出相应的结论(C_1如何变换成C_2之结论);Ⅱ将上述结论推广,得到“一般结论”; Function image transformation problems, students often shift left and right mix, elongation and shortening confusion.The reason is not unrelated to our teaching materials.According to the current teaching material, the function of the image transformation problem of teaching in general Is performed according to the following three steps: I make the images C_1 and C_2 of the two functions used for comparison, and then observe and analyze their positional relations and draw the corresponding conclusion (how to convert C_1 into C_2 ); Ⅱ generalize the above conclusion, get “general conclusion”;