Unless they're students I've had before, I always teach two basic things in every class. Of course, I'm not telling you what you should teach.
The first has to do with knife technique. I usually require students to bring their own chef's knives and steels, if they have them. As part of the class, I teach steeling and show how to sharpen using a stone. However, since there isn't time to sharpen everyone's knife, I let a few of them use one of mine. If give advice on what type of knife to buy, if requested -- and it always is. I also discuss what types of boards to buy (wood, sani-tuff) and what type not to buy (glass, stone, corian, hard plastics).
The second has to do with hot pan technique. Many people don't know to preheat the pan, most don't know how much oil to use for a saute or sear and almost none know when to turn or how often to toss.
I use swap-outs when I have to show prep, but don't have time to get to the finish for the class. I teach techniques rather than recipes. Techniques are cooking. Recipes are instructions to follow. Multiple recipes use a few techniques, this allows you to be canny about what you actually make and what you distribute as recipes your class learned enough to make themselves. That way you don't get stuck with a lot of half prepped standing rib roast. Also, remember you can send them home with food they can finish there. Afterall, that's why they took the class.