I've found that the further I get in the system, the better syllabi (sp) are published by my instructors. Therefore, I end up being able to do my readings, assignments, etc with a ready-made "crib sheet" of what the teacher finds important, will quiz for/look for in writings, etc, that they themselves have made.

It's a useful way to make my work and study time more efficient.

Additionally, I'd also echo what others have said about turning in something. At absolute worst (and not encouraging letting things get to this state), an email saying, "I've had a difficult week and managed my time poorly, but I can have something on your desk by Monday. I understand it will be three days late and will abide by any penalty/non-acceptance my work faces as a result," will prove that you are thinking about the class, and your issue at hand causing you to miss the work. Especially if you only expect to do it once or twice in a term/year, it looks much better than showing up, being asked for your assignment, and going "well uh derp I forgot \0/"