I know it's not.
All the book uses to explain it is a problem I don't understand.
I can put the problem, but it's long and mostly just proves oscillation isn't differentiable.
So my question is:
WHAT IS OSCILLATION?
I suppose that depends on what topic you are covering. I would guess the best idea would be to post the example. (I'm apparently telling you to do a lot of typing. Sorry!)