I know of a friend who is a tuition teacher making consistantly $15k+ a month, very easy to calculate their income by the number of students they teach multiplied by their fees.

But their work is not easy, my friend has to physically teach average 8-9 students a day, 7 days a week to make that kind of money, not to mention the travel time and expenses (she has a car). Even teaching until 10pm! Its hard work.

She always has to reject new students because she physically has no more time to accept anymore new students. If you are a good tuition teacher, parents are willing to pay top dollar.