We've been having some discussion amongst the CS faculty over the last few weeks about whether CS50, the intro computer science class at Harvard, should do away with letter grades and instead switch to SAT/UNSAT. Recently, the Harvard Crimson reported that CS50 is going to do away with letter grades, but this is not true -- the issue is still being debated by the faculty, and has yet to have any formal approval. (I don't know what led the Crimson to report it as though it were a fait accompli.) Given that my opinion seems to differ from most of the CS faculty, I thought I'd put my two cents forth here. Of course, this only represents my own thoughts on the matter, not the CS faculty as a whole (so if you are a Crimson reporter, don't go around reporting this as the final word).
For the record, I used to teach CS61, one of the two follow-on courses to CS50, so the output of CS50 directly feed into my course, and I have a vested interest in the intro course maintaining a certain standard. (My colleague Steve Chong is taking over CS61 next fall.)
David Malan, who teaches CS50, has done a fantastic job at increasing enrollments since taking it over 3 years ago -- I believe the enrollment has more than doubled (possibly tripled) under his watch. CS50 is going great guns and attracting students from all over the University, including many students who would have otherwise never taken a CS class. (Unlike a lot of places, CS is not required for Harvard undergrads as a whole, although it is required for a number of majors, including engineering, applied math, etc.) The course culminates in the CS50 fair where students show off their final projects. It is a great course and David has done amazing things to raise the profile of CS at Harvard.
So, right off the bat, I question the need to change the grading option for CS50, which potentially creates more problems than it solves.
David says that he has been wanting to get rid of letter grades entirely in CS50 for some time, and this year decided to raise the issue for discussion. David's claim is that there are still a lot of Harvard students who are intimidated by CS50 (despite the massive trend in increased enrollment) and that doing away with grades will make those students feel more comfortable trying out CS. While this may be true, I am not sure that we should be designing our foundational intro courses for those students. Harvard already has a "CS for non-majors" course, CS1, to fill that need.
A number of faculty believe that more women will be attracted to CS if they can take the course without worrying about their grade. I can't say whether that is true, but I find it somewhat implausible that what is standing between women and CS is just letter grades.
Even if you believe that doing away with letter grades will increase enrollment, consider the possible downsides. The first is that students who complete CS50 with a "SAT" grade won't have a good idea of their readiness to take more advanced CS courses. Grades do have informational value, and eliminating them makes it much harder to plan one's future course of study. The second is that the course will be less attractive to students who intend to major in CS or engineering, or who are simply used to getting all A's (as many incoming freshmen at Harvard are), so this change could actually decrease enrollment at the top end of the course. It would be fine if the hardcore students could just skip CS50 and take one of the later courses instead, but those courses are not currently designed to supplant CS50 for the better-prepared students. Also, skipping CS50 means missing out on the community experience that I think is important for student cohesion.
The third, and most severe, problem with this proposal is that it will make CS50 no longer suitable for the ABET-accredited engineering degree (which requires letter-graded courses) and the University-wide General Education requirement. So by trying to cast a wider net with CS50, the course no longer satisfies important requirements for certain students, so this approach seems self-defeating.
The compromise proposal currently on the table is to offer CS50 in two flavors: a letter-graded version (call it CS50g) and a SAT/UNSAT version (call it CS50su). It would be the same exact course, just with different grading options. This way students who need the letter grade can take CS50g, and everyone else can take CS50su. It seems clear that this will backfire in several ways. First, many students who take CS50su will later realize they needed a letter grade to satisfy a requirement down the line, but it will be too late. Second, it will create a class distinction between the CS50g and CS50su students. Students taking the course for a letter grade will demand much more detailed feedback on their assignments and more rigor in the grading process (since they will be competing for A's) whereas the course staff, used to dealing with mostly SAT/UNSAT students, will not feel the need to make such fine distinctions.
I have not looked into what other universities do and whether there is any agreement that doing away with letter grades for an intro CS course is a good idea. I know that MIT grades all freshmen pass/fail to alleviate stress associated with grades, which might make sense if done across the board, but it is unclear that changing one class is the right way to do this.
Personally, I'd rather not mess with CS50 right now. It's doing great things and I am concerned that doing away with letter grades would do more harm than good. Of course, many of my colleagues here at Harvard disagree with me, and they are encouraged to weigh in on the comments section below.
Update 4/20/10: The Crimson published a follow-on article this morning discussing the CS50 controversy.
Update #2 4/26/10: Given the many concerns raised, there was simply not enough time for the CS50 SAT/UNSAT proposal to be discussed by the faculty before the deadline for changes to the course catalog for next fall. As a result the proposal has been tabled for now; I expect it will be revisited next year.
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