The main thing to be aware of is charter schools and school vouchers. The latter literally diverts public funds to parents who want to send their kids to private schools.

Charter schools are more subtle. They are privately run schools which often can work around regulations which restrict public schools (for example, they may not have to hire union teachers). There are de jure rules to make sure that these schools are accessible to everyone in the community, but often there are informal methods by which these schools end up being just for white students (for instance, the administration will wait until the school choice period is over and then selectively eject non-white kids).