Hi Merlin -- I think it would depend on the class. I teach some "performance" classes in communication -- meaning that students have to be present for various group workshops, to give speeches, to write critiques of other students' speeches. There is no way to make this up.

Because you didn't indicate that there was anything of that nature involved, I would say take off the day. In non-performance classes, I usually build in 3 days that students can take off without hurting their grade. On the other hand, I allow students who never miss a class to keep the points they earn over 100 for their final grade, as "extra credit."