Since I spent a few years tutoring kids who were being failed by public schools, I have a pretty good sense for some of the curriculum. I will say that everybody I follow who is a passionate supporter of government schools who has made some snarky statement about how proponents of school choice and moving more students, if they choose, away from state schools are "afraid of education" is dead wrong.
One thing that's been taught as fact at least since I've been in school is that there's a clear separation between facts and opinions with no overlap - factual statements are objectively right or wrong while opinions only belong to the person who holds them and cannot be objectively true or untrue. Of course, what this teaches kids as early as grade school is that moral values are opinions and therefore cannot be objectively true or untrue.
This is something that should scare people more than it does and it should be regarded as unethical to teach the distinction between facts and opinions in this way without introducing nuance.
First of all, teaching that moral values cannot be objectively true or untrue is in and of itself the teaching of a moral value. In order to say that no moral statement can be untrue requires a moral judgement in itself. It's a self-refuting idea. If I were to say, "In my opinion, opinions can be wrong." you can't refute my opinion because, by trying to tell me that opinions can't be wrong you're telling me that my opinion is wrong.
Still, when kids are taught this way in grade school, well before their brains are ready to deal with these concepts, and they have to think of facts and opinions in this way in order to achieve in school, this confusion built from falsehood and oversimplification is hard to deprogram.
I don't think I'm being alarmist about this.
In my experience most adults who aren't religious seem to at least try to take the position that moral values can't be objectively true or false. When you press people on this, I think that most people know in their guts that this view is wrong. Just ask them about child brides or FGM - they'll either make exceptions; or, the hardliners will at least have to take a pause before doubling down and telling us that, if it's their culture or whatnot, we can never say that that's wrong.
Anybody who does manage to convince him or herself that what he or she was taught about this is true should become dispassionate - a nihilist. If there are no moral truths then what justifies you trying to change something? If all cultures are equal, why try to change ours?
Most people don't take that route and the only alternative in line with the rejection of moral facts is to become a narcissist. If you're passionate about any moral value without believing in objective moral truth, you're trying to shape the world for "your truth." It doesn't matter if anybody else has a different moral truth, you're going to impose your truth on them because it suits you. Here, I think I'm describing the majority of the illiberal Left.
Yes, beliefs in objective moral truths can be dangerous, too; but, at least there's some coherence. If we understand that values can be true, we can have something to debate. It gives us an opportunity to discuss how we can move humanity forward. Our public schools are a vicissitude to that end.