It's not entirely clear to me that private schools would cater to individuals, or group by ability in the way that tutors do. My wife taught at a private schoo

It's not entirely clear to me that private schools would cater to individuals, or group by ability in the way that tutors do. My wife taught at a private school for some years that did that. They had the traditonal grade levels, coursework was modified for the student. They had to have the grade levels: it was K-8, placing students back in public schools, or a private high school, is really difficult if you don't. This was a learning disabled private school, so your mileage may vary.