What do you think of this idea for a private school?

I live near Philadelphia. Philadelphia’s school system ranks rather poorly. This idea was suggested by someone I know who lives in Philadelphia and is concerned about the future education of his infant son.

His idea is to rent a room with two teachers to oversee about 24 students using an online charter school. He estimates that the cost would be about $6000 to $7000 a year, about the cost of a parochial school. He sees that initially the students could all be in different grades.

This is not intended to be a fix to all educational problems, but rather a means by which middle class parents could affordably have their children educated.

I am a little uncertain about this idea. Let’s suppose for the sake of discussion that online charter schools are adequate. There seems something off to me about having a child’s education paid essentially in full by both the taxpayers and the parents. If it took off, the people most likely to use it would be those who currently send their children to private school, meaning that the city would have to provide additional resources, likely causing a tax increase.

Any thoughts on this?