If you can line the kids up in like 1 hour blocks and bust 8 out in a day you might make some decent coin. Like $50 a lesson, you got a $400 day. That all under the table, no insurance, no designated facility... by the poster that looks like how Mariun's doing it.
Problem is if you got like one kid at 10am, another at noon, and the last one at 3. Then you've got you're thumb up your ass most of the day, and you don't make squat.
I did a few lessons once, wouldn't recommend it. Unless you like hanging out with little kids.