Really (un?)surprised at how many women in this thread arguing against sex education don't seem to have any better understanding of their bodies than the average teenage girl.
I don't think I would expect a teacher to stand in front of a class and talk about specific sex techniques or masturbation. I would not want to do it! I would not have wanted my teacher to do it! But currently boys and girls leave school only knowing a basic reproductive script for sex that damages girls' physical and mental health and weakens (straight) relationships, and wherever else you see sex depicted (tv, films, books, porn) it's the same story.
Fortunately, I think there's a workable middle ground here.
For starters, when teaching the reproductive model of sex, it's not possible to describe it without references to arousal. For males, it's not a possible act without an erection. For females, it's possible to have penetrative sex without arousal, but it can cause internal injury (as well as physical and emotional pain). Females have as much erectile tissue as males. The clitoral (sometimes called urethral) sponge protects the urethra from physical irritation during penetration (the main cause of UTIs). Lubrication and vaginal muscle relaxation (often mentioned in basic sex ed already) prevent vaginal tearing. Arousal is therefore necessary for safe sex and full arousal in females (i.e. the kind that makes the clitoral sponge erect) generally requires physical stimulation.
So ideally: 1) teach accurate anatomy of the full clitoral network and vagina and how arousal changes it. Why arousal is important for functionality for both male and female. 2) I think a very brief generalised comment, mentioning that clitoral stimulation is necessary for full arousal in females, can be made while remaining scientific and avoiding uncomfortable specifics.
Recommended reading:
The Hite Report, by Shere Hite (this has been a problem for so long!) Come As You Are, by Emily Nagoski. Vagina Obscura, by Rachel Gross. John Gottman and his wife's research on desire. Read about Helen O'Connell (who first mapped the full clitoris in 2005!!) and the women of the Federation of Feminist Women’s Health her work built upon.