If you are standing still and holding a heavy iron doorstop in front of the class to demonstrate a wedge are you doing work?

No, you are not doing work in the physics sense while standing still and holding the heavy iron doorstop. Work is defined as the force applied to an object times the distance over which that force is applied. Since there is no movement involved while you are holding the doorstop stationary, no work is being done according to the scientific definition.