I don't know how this played out in the rest of the US, but I have a feeling that there aren't many (if any schools) that allow guns on their campuses, even if for the sake of education.
Same town, different era: My 12 year old nephew received a poor grade and "this is terrible!" written on his essay by his teacher because "What I did last weekend" recapped target shooting with his dad and grandpa at the range.
http://methowvalleynordic.com/biathlon-home/
edit: added link
It was pretty common in the 50s, and up to the civil rights era in the 60s, but after that, the answer is very much no. Currently, possession of a firearm on school grounds is a felony for almost everyone.
Depends on the state of course, but it isn't a federal GFZA violation if you are state-legal and have a state-issued permit to carry.
They have ex-military personnel teaching this as an optional component (you were expected to do CCF or Duke of Edinburgh Awards) - but it is kind of odd to have school kids dressing up in military camo outfits to go into school one day a week.