It's at a support group for home school families. They operate differently than a co-op. Now, normally I wouldn't be worried about getting into switching and the like until much later, but these kids are purportedly gifted.
I'm not sure I would worry about that quite so much. Any kid who is both interested in computer networking and gifted, any any real way in that area, will likely already know more than you could ever teach them. Some simple Googling would provide a cornucopia of information. If they are very intelligent, but have no real interest in computer networking, then your likely going to have the same problem as any other teacher would -- keeping a bunch of bright, bored, kids focused on something they don't care about.
Just as likely, you will get a set of special kids, or more specifically kids with "special parents", in which case, I wish you the best of luck. I'll leave it at that unless you want to split off a parallel thread for R&P.
My thought would be to focus on the "why" behind things and relate them to real world examples. Why is a broadcast packet like yelling in a crowded room? Why is an ARP like asking every person in the room if their name is "Fred". Why are subnets like people being in different rooms. Stuff like that. Its easy to look up the commands to do something on Google, or even a old school dead-tree book. Understanding the concepts so you know what you need to do in the first place is more key.