I don't OC at K-12 schools (unless I'm visiting Autosurgeon in Coloma!) because I don't have a 100% grasp on the laws that concern K-12 school carry. Once I take the time to learn the important points and memorize the laws, I would OC at a K-12 school if I had business there. However, I never have any business at K-12 schools so you probably won't see me at one.
As for college campus carry, I would definitely, without a doubt, OC at my university if it weren't for the fact that they would expel me. (I'm only one month from graduation!) I would actually feel more comfortable CCing at my university though, and before you all jump down my throat, let me explain why. Yes, OC deters criminals. Most criminals. The kind of criminals that want your money or your fancy watch. Those are, say, 99.9% of the criminals out there. However, much of the reason I would choose to carry on a college campus is be be able to defend myself from a campus shooter. If the campus shooter is there for the sole purpose of killing as many people as he can, I feel that the argument of "you'll be shot first" does actually apply in this case. Don't get me wrong - I usually call BS on that argument too, in 99.9% of the situations we may encounter, but when someone wants to kill as many people as possible, it does make sense that they will shoot you before shooting others because you are more of a threat.
In conclusion to this post (which turned out longer than I intended), yes, I would OC at a K-12 school, and yes, I would OC on a college campus as well as CC in the classrooms if it were legal and not against the college's rules for me to do so.