Hi bob,
First I would recommend that you attend an MOC event like a seminar and make sure you know the law forwards and backwards. If you're doing something someone in government doesn't like, you better make sure you're doing it right.
Keep in mind that I am not a lawyer and what I tell you does not constitute legal advice.
Per
MCL 123.1102 and
CADL v. MOC PUBLIC schools are "quasi-munisipal" organizations that are preempted under state law from regulating firearms to and extent stricter than state law. PRIVATE schools are private and as such not subject to MCL 123.1102 because they are not units of government.
If you have a CPL and you are openly carrying your firearm, theoretically, there is nothing the school can do about it, however, many will try. Things such as putting up signs, going into lock-down, and calling the police. Essentially harassment. Whether or not they can get away with these this is questionable unfortunately. Schools have a lot of leeway when it comes to safety and maintaining order.
I hope that helps. If you have more questions, please ask them.
** Edited to distinguish between public and private schools.
