Private schools can’t discriminate against protected classes but they can ABSOLUTELY use behavior as selection criteria. That said, sometimes what it takes is a totally different approach to discipline to reach “problem students,” approaches that aren’t often available in the public school context. Some respond well to iron-fisted authority, some respond well to restorative practices and circles, etc., while some need a ton of personal attention. Some “problem students” have problem parents, some don’t. It’s a shame that our public education system is as underfunded as it is, that school boards are political, that our public system is, by-and-large, one-size fits all. Charter schools and magnet schools provide some free public alternatives, but most progressives label them as destroying public school funding (at least, until they realize, like I did, that where I live, the standard public school system is a political shitshow and that sending my kid there would lead to conservative indoctrination). My local charter is chock full of incredibly passionate teachers that have an expansive view of the world. Of course I’d sign my kid up for their lottery.