When I went to review my son's 5th grade sex ed. material, it was during the height of the AIDs epidemic and the material looked clinical and harmless.
Boy was I wrong. What I discovered was that kids were not even ready to handle a clinical description of biologic functions, let alone any mentions of homo-sexual activities. The boys went around for weeks later, teasing each other about having ovaries and vaginas.
A co-worker told me her son and some of his male friends forged gymn excuses saying that they couldn't take gymn because they were having their periods.