One knock on school vouchers is that won't be generous enough to offer students a chance to attend a private school.

Are private schools too expensive? Consider this: the average public school spends, very roughly here, $10,000 a year.

The Mackinac Center for Public Policy reports on a group of private schools where tuition will be $2,200 per year.

How do they do it? Students "spend four days in the classroom and one full day working each week. Their earnings go toward their school costs."