A former university academic dean, I know of hard-nosed Calculus professors who started off their introductory class by saying to the students, "Look at the person to the right of you and the one to left of you." Then they continued, "One of you is going to fail this class." Then to add hard evidence, the professors asked for a show of hands of those who were taking Calculus for the first time, next they would ask how many were taking it for the second time, and finally how many were taking it for the third time.

By this point most of the students were beginning to get the message that Calculus is a really tough subject and the odds of flunking are high if you fool around and don't develop the discipline to study hard. Students got the message; it's a costly proposition to fail Calculus, a gateway subject, if your ambition lies in the more lucrative disciplines of the hard sciences. Chances are, if you can pass Calculus, you won't earn your living asking, "Would you like fries with that?"

Sadly, the opponents of abstinence education don't want an equally tough approach to the realities of sexual activity. Their mantra is: "kids are going to experiment, so give them condoms." But given the unforgiving nature of a sexually transmitted disease such as genital herpes – once you get it, you've got it for life – not to mention some of the others like human papillomavirus (HPV) that increase the odds of cervical cancer, or the lengthy and unrelenting demands of taking care of an unplanned infant, I think it is only fair for the kids to know exactly what their odds are when they are given condoms and told "if you're going to do it, use protection."

To answer this question factually, we need to look at the outcomes to see just how effective condoms are, not theoretically in a testing laboratory, but in actual usage by teenagers. What the data clearly show is that in real-world conditions, condoms work much of the time but they certainly don't work all of the time. Now there's a comforting thought for any young girl when she's contemplating the prospect of (a) putting her hopes and dreams of a college education on hold in order to care for a baby she wasn't ready for, or (b) the never-ending discomfort and embarrassment of dealing with herpes, a disease she'll have to cope with for the rest of her life and one which she could pass on to anyone she is intimate with; she can even pass the disease to her own baby.

The National Center for Health Statistics analyzed the data from the 2002 National Survey of Family Growth and produced estimates of the probabilities of a first birth occurring by each birthday from ages 15 to 20 for women completing the survey who were 15 to 24 in 2002. Among women who used contraception at first intercourse, the probability of giving birth at each age is roughly half (half!) that of those that did not use contraception. What is not as often pointed to, however, is the fact that the odds of giving birth even to those women who did use contraception were still significant and rose to 17 percent by age 20.

Like Calculus, sex is a tough subject, one that you can't fool around with – one that requires discipline and self control.

But there is another comparison that the "they're gonna do it anyway so give 'em condoms" advocates of condom-based sex education (in their battle against the abstinence approach) treat as irrelevant. While the probability of a sexually active female giving birth approximately doubles between 18 and 20 years of age whether the young women uses contraception at first intercourse or not, if you're a teen who does not have intercourse, the probability of giving birth by age 20 is the same as it is by age 18; it's zero. No sex, no babies and no hopes and dreams smashed to pieces. Pretty simple.

What the data are telling us is that out of every 24 girls in sex-ed classes where they are handing out condoms, the odds are that about four of the sexually active ones can forget about going to college even if all of them tell the guys they have to wear those condoms they got in sex-ed class. When a girl just says "no" to five to ten minutes of awkward fumbling around in the back seat of some guy's car, what's it going to cost her? Maybe five to ten minutes of popularity with a guy who probably won't be around to help pick up the pieces of her future.

It is sad to think about how, for the sake of a little attention and maybe even a little affection, a lot of girls say "o.k." and then have to contend with the very real possibility of ending up pregnant or infected even when he wears a condom. To my mind, clearly facing these hard realities of sex makes the choice about sexual activity very simple and very uncomplicated.

There is a mountain of media out there promoting a phony philosophy about the joys of casual, risky sexual experimentation; one need look no further than the junk advice featured in magazines like Cosmopolitan to see just how pernicious it is. Even the "Dear Abby" column in many daily newspapers spreads the expectation of sexual activity for teens.

This assault will not be neutralized until a brigade of those who know better find their voices to convince today's Sex-in-the-City generation of misguided young women that it is discipline – it is having an attitude that says, "I won't mess up my tomorrows by fooling around today" – that opens the gateway to achieving their dreams and ambitions, whether you're talking Calculus or sex.