I would suggest that you talk to them like they are Young Adults not children. Nothing P.O'ed me faster at that age than been treated like a child. It's something that I always try to avoid. There are somethings that you cannot, for obvious reasons, tell children and there are certain limits on what gear they can have. When I run into a limit, I always make it clear that it is a limit imposed on me by law, custom or whatever and that I have to respect it. Being individuals, there will be a wide spectrum of ability. Some will take to it like ducks to water, some will struggle. Helping the ones who struggle is the best part of a challenge. The only other thing that I can offer is that you tell a lot of related jokes and story's. They are great for making children remember.