The oldest enemy of all...

Time, there just isn't a whole lot of it to explore in the curriculum set up that I am a part of.  We have something called a spiral curriculum where we do a mile wide and an inch deep.  I'm not the biggest fan of it because it means we cover a standard a week roughly.  We are also starting to hit problems for science process skills because taking a week off to do an inquiry lab just isn't feasible without dropping a standard at least.

The other part is that to explore the more puzzle based games requires time to play.  Arcade style games work great for a class period or two but you lose the advantages of a grand puzzle solver.  The same issues occur if you wanted to bring in a game as a narrative for an English class.  How do you guarantee everyone has played and how can you justify 9 hours of playtime?

Schools and teachers are also in a weird spot, especially with an AAA game, where they have to convince the parents that the games they are bringing in are for educational purposes and not a lazy teacher.  You'd have to have a very unique school set up to make it work.