This is a curriculum by Katherine McLaughlin at Planned Parenthood, Karen Topper at Green-Mountain Self-Advocates, and Jessica Lindert. I know several folks who use this curriculum and really love it. It was developed for adults, but they have a school expansion now. If you already have the adult version you can get the supplement school materials for free.
I think you get great bang for you buck with this curriculum. It covers different types of relationships, public/private, friendship, communication, decision making, moving from friend to partner/sweetheart, many roads to relationships, being in a relationship, communicating about sex, decision making about sex, challenges or things that could go wrong, do you want to have a child, avoiding pregnancy, and getting a STI.