Don’t you stand in FRONT of a whiteboard? They hang flat against the wall. Someone has figured out how to flim flam the school system.
The idea is that the prof will tell the crazed killer —
“Pardon me, sir, could you please wait until I take the board off the wall and hold it in front of me for protection, before you aim your gun at me.”
And naturally the killer will oblige him...
(/sarc)