I don't really know exactly what the curriculum looks like now regarding sex education in schools. but I do know if you've waited til highschool to educate, you have waited too long.
I would prefer to have my child taught the biological aspects of reproduction as part of biology/anatomy/science classes - that does not include the sex ed curriculum. Additionally, I would certainly not oppose having age-appropriate sex education enter into the curriculum in early middle school, or before (omg, these children are so grown by grade 5). Abstinence would certainly be one of the many options and considerations of the curriculum. But abstiinence on its own, or as a main theme? I wouldn't be comfortable with that at all. Children and teens need to know as much as they can be taught, given all the alternatives, and encouraged to open dialog with their parents. Abstinence education is fine, in the home or church, as long as the children are given the whole story. Abstinence is something our family teaches us, encourages us and expects us to follow. Sometimes it works well for some teens. but far more often than not, not. How do I know? because when I was growing up, we may have had basic sex ed at school, but our parents and churches preached abstinence until marriage. it was the only option given. it was really not all that effective in preventing pregnancy, SDTs or worse.
it was so simple when I was growing up: "if you have sex before marriage you will go to hell..." end of story. but somehow we knew that was a crock.