How to grade? I developed a rubric based on apparent level of preparation, accuracy, and presentation skills. As I call on each student, I write down his or her name, and assign a grade from 0% to 100%. I get to call on most students each day. When students volunteer to help they get 100% if they're right on the money, and nothing at all if they're not.

I also select two students each class meeting to grade the other students, which is a tremendous help to me. The students are generally much less forgiving than I, which gives me courage to assign low scores. I assign the final score myself for each presentation.

The course grade consists of the average of these presentation grades, along with a few other things. I give each student a limited number of opportunities to be absent, and then start assigning 0% for additional absences. I also give them a limited number of "declines," that is, opportunities to say, "I'd rather not touch that one." If they overrun that limit, they get 50%, which pulls down their average, but not as much as not coming to class at all. In fact, few students use their "declines." So far, none have overrun their limit (only 2 or 3 each quarter).