But they didn't learn anything new because I'd already taught them everything. They clearly understood the biological differences between boys and girls. They understood where babies come from and how a man and a woman both required to have a baby. They knew about how sperm fertilizes the egg, etc.
I've never implied a problem with sex education for children. But I decide what's appropriate for my kids, not you. And it's sure as shit not ok for a teacher to make that decision for me, and then keep a secret to hide it from me.