If you're looking for a few good books to help have some of those difficult conversations I recommend Sex and the New You published by CPH. They're easy to read and cover some nice topics in relation to God's plan for men, women, and sexuality. Some of the topics include: Gender is More than Body Parts, You're Changing into a New You, Is Sex a Secret?, and information about what's going on with the opposite sex.
There are a few ways to use these books:
Let the Pastor do it!
It's perfectly fine for a Pastor to have these discussions during confirmation class but it works a lot better if the genders are split up and a male and female leader can be a part of each group. Having a man in with the girls is good so they can ask questions about boys and get honest feedback and vice versa for having a lady in with the boys, however, there may be times when the discussion will go better if the opposite gender is not in the room.
It's the parent's job!
Another option would be to have a parent meeting and introduce the parents to the books and encourage them to have these conversations with their kids. It can be a difficult topic for parents but it can open discussion that will be beneficial all through the teen years.
It's a group effort!
Get a group of girls together at somebody's house and let any moms join in the discussion for a fun evening of bonding and do the same for the boys and dads. That way the kids have their friends and won't feel completely on the spot and neither will the parents.
God made us special people and the ability to have intimate relationships is a gift. Let's get the kids started in the right direction!