They're talking about 5 year olds here, not high schoolers.
The best sex ed a kid that age needs is to know that boys/girls have cooties. STAY AWAY!!!
Actually, I can imagine a type of sex education for 5 year olds, but more along the lines of “impulse control training” for the boys, and “assertiveness training” for the girls.
A lot of gender training that used to be the norm, has long been under spiteful attack by those who didn’t see the inherent value of such training to male and female identities. And this has become even more valuable because of so many broken homes today.
Boys need an effective male role model, and girls an effective female role model to base their behavior on. And yes, this is sex ed, a lot more than fussing about sexuality, which is way over the heads of five year olds.
At the same time, five year old boys unpredictably but purposefully need maternal affection, as girls do paternal affection, and not just as contrast to their gender role model. The role model is “what I will grow up to be”, but the affection model is someone of the opposite gender who provides unconditional support.