• A student brings you a piece of writing and as you glance at it, you notice that he has problems with periods—many are missing, and a few are out of place.

• You are moving around the room as students work on a math assignment and as you sit down beside one student, you see that she has done some of the problems correctly.  When you look a little closer at the ones she got wrong, you see that she has made the same common error time after time.

• A student hands an assignment in and you see right away that he has missed the point entirely—he might have been on a different planet when you were teaching the material, because he has done everything wrong, and you don’t know where to begin correcting the assignment.

Teachers have passed down the method for handling these situations for centuries—mark the papers, pointing out the errors, and ask the student to correct the errors.  The teacher may look at the mistakes with the student and review the proper procedure, or may ask the student to refer to the textbook to find out how to do the work. In my experience, this approach works only with students who have got nearly all the answers right.