I remember being in fifth grade and they brought all the girls in my grade into an empty classroom where the nurse showed us a video about "maturing" and all that. it talked about sperm and eggs but they never explain how the whole ordeal occured. When i asked they said my mom should explain that to me at home. xD Although it wasn't until that summer when she was driving me home from girl scout camp that my mom told me. At eleven, being the first time i ever heard anything so peculiar and shocking, didn't even know what to say. I didn't know why anyone would want to do something so disgusting! At the time, I could tell my mom was really nervous to tell me, but now my mom is alot more comfortable with talking to me about that subject.

Bella, at 11 years old your kid probably already knows more than you think, but also has probably more misinformation and misunderstanding than you would believe possible as well. At that age its all fact mixed with fiction largely obtained from the playground.

What you need to do is help him clear up the misinformation he has.

As how to start the conversation, perhaps just shock him into sitting still. Start by shouting "SEX!!!" and while he is still stunned say "Right, lets talk"