I have mixed feelings about this. My son is in the 5th grade, and he's quite innocent, so it seems a little early to expose him to the topic (this year). On the other hand, he makes some random comments that he has heard from other classmates, who probably have older siblings, and seems to be at the threshold of being exposed to facts and half-truths. So doing it in a formal fashion is probably better. \n\n4th grade is too early, in my opinion.
How do you feel about sex education for 4th and 5th graders? Is it too soon?