Now, again, if they were simply teaching the science of sex, I have no problem, whatsoever, with that. That's applicable. There is some academic reasons behind it. But scant focus is applied to this aspect. Really its just a soapbox for some blowhard to blather on about clandestine sexual trysts and to condone kids having sex.
This is all anectdotal, but when I was in Public School, we were taught that having sex could lead to diseases. We were taught that there were ways people protect themselves against said diseases. We were even given a little chart that showed the effectiveness of each way someone might go about protecting oneself. (For instance, the latex condom being x% effective, abstinence being 100% effective, and so-forth.) I have never in my life understood what is not scientific about this. I can think of no reason not to teach people this.