Just a few years ago, when I was in junior high, some people carried around folding knives or multitools. Somehow, against the principal's best efforts, word had gotten out that the district regs allowed knives that were too small to count as weapons by state law. Now, our principal lied about that, said that they were illegal, but she had just handed out printed copies of the handbook that explicitly stated what constituted a weapon, and at least some of the teachers didn't care. The art teacher actually borrowed a classmate's multitool when he needed a knife, and didn't appear to give it a second thought. On the other hand, though, my best friend's girlfriend got expelled for having a pocket knife, I'm not sure if it was a case of not knowing the rules well enough to challenge it or if the blade was too long.