I missed this when it first appeared, but caught it in todays Atlanta paper. My favorite passage in this biology professors despairing account of her students unfounded confidence in their mastery of the material:
In the face of all evidence to the contrary, my students exhibit an unswerving confidence in their own abilities. They earnestly assure me that despite test scores in the single digits and an inability to answer questions posed by their teaching assistant, they really know the material: "It just doesnt show in my grades."
Read the whole thing.