You need to be aware that in addition to the dorms and classrooms specifically mentioned in the law, certain Universities that are mentioned specifically in the State Constitution can have gun bans that also have the force of law. I believe these are MSU, U of M, and Eastern Michigan University. I know that U of M has banned guns on campus, and I believe MSU has as well. I don't know about Eastern. That means that violating the gun ban at those universities is not just a violation of policy, but an actual violation of the law.
As far as "dorms and classrooms" go, some schools are putting as broad a defination as possible on classrooms by including any area where a class might possibly be taught. This includes parking lots (driving classes), athletic fields, outdoor nature areas (biology classes), etc.
Personally, I try to stay off campuses as much as possible.