There is no way for objective instruction to take place with regard to human intimacy. In a classroom, anything less than objective instruction is indoctrination. That immediately puts schools and families at war because of their different goals. Parents have the right and responsibility to educate their own children without interference. Sex education programs for adolescents are invasive and do not respect the modesty or sensibilities of the recipients.
Teens are generally dependent on others for most aspects of their livelihood.
The liberal framework keeps trying to disconnect sex from marriage and family, as if it really can stand alone. As long as the true reality is ignored or denied, problems like teens with AIDS, babies, abortions and suicides will plague us. It is fair to say that no one should feel guilty about nonexploitative sexual practices. But that does not address that many people aren't farsighted enough to make wise long-term decisions and that these are the people who, in another time, were most helped by traditional sexual morality. There was a reason that people married so early in that period.