… mastery, we tend to teach in a way that will help only a minority of students do exceptional work. Conversely, we’ll leave an equal number of students behind doing unimpressive work, and the majority of our students settling for mediocrity. When teachers have the bell-curve in mind as a mark of their success, they tend to design their lessons so that the majority of students will not have the opportunity to push past their initial limitations. The final irony is that in pursuit of teaching excellence, some of us unwittingly prepare our students not to learn.