Risque title today, eh? So one of the joys of being a FACS teacher is the sex ed component that accompanies so many of your units, particularly in Child Development when you really can't skip over that whole "How are babies made" question.
One of the challenging things about handling this subject matter is that you've got kids all the way across the comfort spectrum: some will have no problem publicly asking the most graphic questions, some wish only to curl up under their desks and die. Most are somewhere in between.
Because of this, it's really crucial to work to establish an environment in which nobody is spending a full 52 minutes desperately pleading with God for a bear to walk into the classroom and eat them so that they can escape this discussion. So naturally you're not going to jump straight into "When a mommy and a daddy love each other very much...", but instead you're going to take some time to create that more comfortable climate first. Even with that, you're going to need some boosters here and there to keep things light and break the tension when necessary.
Here's one of my favorites.
For background, I use guided (sometimes called "skeleton") notes for my classes - they're already formatted and have most of what they need, but they have to follow along and fill in the blanks as we go. It's enough to keep them paying attention and on task, but not so much that they're focusing only on copying to the exclusion of listening (or that their hands cramp up and they begin crying carpal tunnel).
When we begin our discussion of conception, I make no assumptions. We start with the basics - the essentials of female and male reproductive anatomy. As such, it's obviously necessary to work with some diagrams (NOT pictures, diagrams). When I have the female anatomy on the board - and their note sheets - and we go over the different structures, I've never had any issues at all, they take it stride, almost ho hum. As soon as we flip to the male anatomy, that changes - you just can't project a penis onto the board (again, a diagram people!) without the room immediately becoming charged (and you can really see it in the less comfortable kids' faces - "ohmygodtheresapenisupthereitsapenisicantdothis WHERE IS THAT BEAR, GOD????"). Additionally, you have your less mature kids who are desperately, desperately trying not to giggle because they don't want anyone else to think they are immature. And of course everyone else is aware that things suddenly got weird and now everyone's a bit on edge.
So here's my built-in way to diffuse this inevitable event. For about seven or eight blanks in a row, they have to write in the same word over and over: sperm. By about the third of fourth one they begin to catch on, and by the sixth time they're writing "sperm" everyone is laughing out loud, the tension has disappeared, and "sperm" is now a meaningless word because they've looked at it so much and we can now move on.
Seriously, works like a charm, every time.