How much preparation and planning goes into every hour that you teach?
What about grading?
Do you think your rates reflect the amount of time you put into teaching?
If you are a student, do you value teachers who actually work outside of the lesson preparing it for you?
Personally, I would say there is about an hour of extra work for every hour of teaching, lesson time. What does that mean? It means I'm working that time for free or my rates are actually much lower than they appear to be, taking into account all the effort that goes into it.