My Geog professor did something similar, instead of having us pay for a $100+ text book, he gave us a CD with all of the content we needed on there. Pretty cool..
Since you're a physics professor i assume you mean wiley plus? I remember having to use that a couple of years back, while it was a good resource and helpful for problem solving I know it depends on the individual professor. My prof was very lenient on the program's parameters and it was helpful. But i have known professors to be sticklers and stress students out with a bunch of homework assignments.
