How does this work?

"Teachers are so racist that if you let them carry guns to school, they will just start shooting the black students."

Wait a minnit...  Why are there so many racists permitted teaching classes?  With or without a firearm on them, why are they up at the chalkboard if the only thing preventing them from committing a homicide is the fact they can't legally bring a gun to school?  Wouldn't one teacher that had illegally brought a gun to school have lit up a black student by now if racist teachers were so prevalent?  Do the parents know a good proportion of their kids' teachers are this homicidally racist?  Why did these racists get into teaching in the first place, didn't they know some of their students would be of a racial background they didn't like?

If this is all true, you got a bigger problem than a few future CCW strapped teachers.

Wait!  I got an idea.  Only permit the black teachers to go armed.  Problem solved.