So often we emphasize concepts in reproduction and forget that our teen might not understand the basic information behind the concept. For example, although they might know that a condom helps prevent pregnancy, do they know how the condom does that?
There is so much more to teach your 15+ year old son now that he is through puberty. You are preparing him for sexual maturity.
We are so careful to make sure that our daughters are ready for their first period. But after they start having regular monthly periods, they have likely reached the end of puberty and have entered sexual maturity.
If you have adolescents who are 15+ years old, they have likely reached sexual maturity. Now it is time to keep the teaching going, but at a new level. This age group is often more challenging to get their support for your teaching attempts, but the topics will definitely be of interest to them.