slashdotted today! Sorry, Lee, if you are getting unwanted attention. I think it is funny how people assume that the class has "no grades" because of the XP system -- when really, it is exactly the same system everyone else uses (each assignment is graded, the grades are combined), the only differences being that:
1) Averages are delayed. By delaying averaging, you delay achievement, which can be a good thing, because it gives you something to look forward to.
2) Your grade never goes down. People HATE losing progress. If you've been getting A's all semester, and then you get a D on your final project, you have the experience of going from an A average to a B average, and it feels like lost progress, certainly a decline. But, if you've been getting A's all semester, and all this has earned you is a "C-", then when you get a D on the final project, you are still making forward progress to a B. Same final grade, but you experience going from C- to B instead of going from A to B.
3) By explicitly calling it XP, it associates the experience with a game, which makes sense because the class is about multiplayer gaming. I suspect there is a novelty to this that lends it appeal, but of course, this would fade if it were widely implemented.
4) By making everything about cumulative points, it is actually easier to add in extra credit -- you just throw some more points on there. With an averaging system, you have to talk about adding percentage points, and it can be nebulous and confusing. A simple clear extra credit system makes it easier to give extra credit, and increases motivation to want to earn it, and therefore the teacher is more likely to seek and find novel opportunities to give it, and the students may try harder to earn it, since they know exactly what it means.
It seems strange to me that no one has done experiments of this kind before to see if an "additive" grading system as opposed to an "averaging" grading system provides more meaningful and motivating psychological rewards. Anyone know of research on this? I'd love to see it. I just got my copy of Punished by Rewards today -- maybe it has something.