This is a terrible position to take. Anyone can be educated.
The thing is, nobody likes being flat-out told they’re wrong, and with the way arguments on the internet go, that’s all that will ever happen.
Most of my friends are heavily conservative, but I’ve learned how to have productive conversations with them about issues, and it’s almost always “This is how it benefits you if it were different.”
It’s difficult sometimes, but it’s worth doing, and it’s important to understand that the guy you’re talking to isn’t the enemy. He’s just another dude.
Period flow can happen without warning, and even if there is a warning, it’s not usually something that girls are comfortable enough with to want to announce the reason in front of a classroom.