You can buy an outlet tester to check whether ground is properly wired (in that outlet).
If you're being zapped by a whiteboard hanging on a wall, then most likely it is static electricity generated when you walk across the floor. You didn't specify but I'm guessing the floor is a plastic laminate?
You could put down anti-static floor mats. For example under each desk. This would keep you from building up charge as you move around. Running mats across the entire floor may prove cost prohibitive.
