One problem is that school boards are not allowing teachers to carry. I would think there is some kind of supremacy that school boards can’t over ride state law. I know the state laws on concealed carry allow an employee of a college or university to carry while on the job on campus no matter what the local rule is. That element needs to be resolved or might as well no have a law that allows teachers to carry.
Better to require all teachers and staff at public schools to take NRA gun safety courses, then allow them to carry or not. Signs on entries saying “This school protected by Second Amendment and armed teachers.” Perhaps in any given school many will be armed, perhaps only a few or none but an attacker has to consider the likelihood that some are armed and he might just get shot down before he gets to kill students and go out in a blaze of glory, or at least the attention he craves for his death. Florida is implementing such a custom. We won’t have any more school shootings, I think, until trannies and other crazies get their hands on RPGs or Hamas rockets, but that is a different problem.