I try to do the very same thing regarding school-related print-outs. It was an absolute nightmare when, this past semester, most of my assignments required laborious print-outs. It was absolutely ridiculous how much paper and ink were wasted on these readings! What I'd do is print notes and readings on used paper, and first drafts of papers on used paper. It's a much more economical solution.
And changing the margins would help out as well. Hopefully, that won't encourage professors and teachers to expect more writing of students when it's not necessary. If we can change the standards of margins and page lengths to suit more environmental needs, academic papers would be less hassle, both for student and the environment.