I must disagree on the "fact" about the dementors. On page 14, chapter one of Harry Potter and the Order of the Phoenix, Fudge states "That's right. And they're [the dementors] breeding. That's what's causing all the mist."
Ts site has a bunch of great ideas for using harry potter in the classrooms, including crafts, games, centers, printables, lesson plans, and articles that support the use of hp in the classroom (for the non-believers!)