Ask them what sorts of images they get of young people and their sexuality on the television. In magazines? Do/did they or their friends feel pressured to have intercourse at a young age? How old were their peers when they began to be sexually active? How old do your students think a person should be before becoming sexually active? And, is abstinence a viable choice? Why or why not?
Most mammals, other that humans and our artificially selected stock animals, have relatively small breasts when not nursing their young. Their breasts swell with milk for the duration of nursing, and then shrink back to their near-normal size afterwards. Humans, however, have noticeable breasts all the time, which also increase in size during nursing.
Why would nature cause the evolution of larger breasts (mammary glands) in human women? Why would this be adaptive? Hint to your students: Think about the early humans, who were short of stature, muscular, hairy, but walked upright. Is it possible that this is one way they could recognize potential mates at a distance?