My grandkids' school uses those styrofoam containers and plastic forks now. I don't think those things will cut anything. That could be why the girl brought a knife to school or maybe even to cut an apple
I think you may be right!
Another reason she probably didn't get in trouble previously has to do with lunch duty. Different teachers have lunch duty each week or day depending on how the school is set up. There is a good possibility that the girl was spotted at some point, but the teacher on duty at that time just didn't see a problem and let it go. This last time, there was a teacher who beats every rule into the ground and she took it to administration. Once admin steps in, that's it--game over. I always deal with problems myself unless it's a MAJOR issue. (Like the time I walked up to the principal after my fifth period class and said, "I have something for you." When he held out his hand, I dropped a handful of bullets into it. I've never seen him look so startled in his life! The kid got suspended for a few days: he's in prison now--unrelated.)