Variability #1

If the room temperature were to vary by two degrees in the course of one hour, it would be unlikely that anyone would become uncomfortable.  A variation of two degrees would be subtle and acceptable.

Variability #2

In contrast with the first example, this variation is much more profound.  In this case, the room temperature would at its lowest be a chilly 14C, and at its peak 28C.  Neither of these temperatures is comfortable, and a variation of this magnitude is unacceptable.

Does this remind you of one of your classrooms?