Honestly I think it's fine for them to teach that in schools without the parents getting a say. I think they should be allowed to teach it, but then if the parents really don't want their kids to know then they can keep them off for that day or something. Just to be clear, I don't think kids should be forced to learn about it if the parents really don't want, but I also don't think some parents should have the power to stop it from being taught to all the kids. Teaching kids about it is just giving them the information, they can decide from there whether they agree with it or not, so I don't think that's the same as forcing them to have certain viewpoints, unless they get in trouble for disagreeing with something of course. Sort of like how all kids are taught about evolution, but then they can decide from there whether they want to accept it or not.