Who is this sign supposed to deter? Sensible, law abiding people, the 99.99% (totally my guesstimate) of us would never consider carrying any weapon into a public building like a school. How about the .01% of criminals, evildoers, or deranged men that we keep reading about not only carrying weapons into schools but then shooting people indiscriminately. Would such a sign deter them? Would someone at the end of their rope, intent on doing harm, and armed to the teeth stop in his tracks by this sign and mutter: “heck I was unaware. I guess I will just turn around and go home.” Of course they wouldn’t.
Thus, the sign deters no one. Then why put them up? It seems like a small waste of money and time.