Greg, & everyone:
I have never been told that I could not carry a knife at school but I really do not know if other teachers have been told not to or not but most male teachers I know carry a pocket knife. My multi-tool pliers are appreciated by several of the other teachers because I have used them to help them. If you think about it though, Home Ec has many more accessible blades than anywhere else. I even have paring knives etc, for cooking for various events during the year.