You’ve probably heard the phrase, “Good is the enemy of great.” I don’t know where it originated, but I know I first came across it in the book that made it famous: Jim Collin’s Good to Great, a fascinating study of how some companies came to dominate their fields. The basic logic is simple: if you’re satisfied with being pretty good, there’s no reason to work harder to become great. True enough, and important to remember. I’ve seen the “good is the enemy of great” phenomenon almost everywhere. In students who decide a B- isn’t that bad. In teachers content with their familiar lecture or syllabus, changed very little...