Isn't it more fun to leave this to preachers, pundits, and politicians? I remember a Right Wing woman a few years ago arguing against sex ed, stating all that was needed was to teach kids to keep their hands out of others underpants.
Now, in the real world, it is difficult do design an experiment. Teen pregnancy rate has three variables: sex education, sex practices and frequency, and availability of contraceptive pills/devices. These three are the variables.
I know of no comprehensive study on these. Most focus on the teen pregnancy rate vs sex education. However, sex education could be anything, most school districts focus on "teaching" abstinence, which may (according to research) delay sex, but not prevent it. So even that measure misleading. Good luck.
The first step is to ascertain whether the sex education class promotes various forms of contraceptives. Some classes only teach abstinence.
After you've found classes that promote contraception, then determine how you're going to measure the students' future behavior.
You could poll people without children who have taken (and passed) one of these classes in the last 5 (10?) years. Only two questions are necessary. Do you have sexual intercourse? Do you use contraceptives? A third question could ask those who don't use contraceptives -- Why not?
Then you can poll people who have not taken a sex ed class that promotes contraceptive -- asking the same questions.
Many studies have been done in this area. In designing any experiment, you first need to review previous studies in the area to find out what variables are important and/or need to be controlled. Also you will get some ideas about how to contruct your experiment.
I searched Google under the key words "'sex education' contraception studies" to get these possible sources:
There are more studies out there.
I hope this helps a little more. Thanks for asking.