Lots of people talk about a syllabus as a sort of contract between professors and students in which professors tell students what will be expected of them and students are informed about how their final grades will be determined. Of course, this contract is one-sided and typically gives students no input into the process (yes, there are exceptions), but at least they typically know what they’re getting themselves into by taking a given course. As I tweak my syllabi in the week or so leading up to the beginning of the semester, though, I often find myself asking questions like “Should this assignment be worth seven percent or eight percent of the final grade?” and “Which of these assignments do I expect to take students more effort?”
Because these questions have no clear answers, I end up making arbitrary decisions to determine how each requirement will contribute to the final grade. This is especially a problem in new courses or courses in which I have new assignments (some of which have not actually been written when the semester begins). In one previous course two assignments were given the same weight in the final grade but one ended up taking students about half the time, thought, and effort, of the other. I tweaked the weights the next time I taught the course, but the “contractual” nature of the syllabus prevented me from changing the weights when I realized the problem.
I don’t think that setting course requirements in stone at some arbitrary point (for me, this is when I make copies of the syllabus for students) is a bad thing. Students have a right to know how their grade will be determined. I’ve actually heard students in other people’s courses complain when assignments were dropped because they were hoping to use those assignments to bring their grades up. I do think, however, that it is important to recognize how arbitrary some of these decisions are and carefully reflect on them throughout the semester so that we can make adjustments for the future. Just because we set something in stone doesn’t mean that it is necessarily correct.