Comprehensive Sex Education

The thought of even having this issue scares me. How does one even judge when their child is ready enough mentally for this discussion? Some parents just wait for the school to graduate the child to the grade it is taught in. Others try to prepare them and discuss certain issues with them first. Aren't we really teaching them by example though, before any teacher based learning begins on either subject? The way that we interact with our partners (or lack there of) shows our children so much in regards to how we view sex and abstinence. That's why in school I believe that we must have comprehensive sex education. I don't understand why taking values and self-worth mixed with facts and statistics is so scary to anyone. In this day and age don't we want our children to be fully prepared for whatever happens in life? Ignorance gets you no where in life!