If all you are teaching is casting techniques, it is not necessary to even put a fly on the line. I piece of brightly colored yarn will suffice. The best program for teaching kids about and "how-to" flyfishing was a day camp put on by the Mid-Atlantic Council of FFF. It covered brief lessons (bearing in mind attention sans and simplicity) in entomology, hands-on flyting, knot tying , lunch and finally an hour or so of fishing in a pond for bluegills. The flies included a green weenie, and a few of the classics like the Adams and woolly buggers. I personally included a foam beetle, and a foam ant at my table. FFF may still have copies of the small handbook which served as a guide for the instructors conducting the course. My grandkids are grown now but they still fondly remember the fun they had participating in that day camp. Also, you might want to get specific details as to the amount of and kind of space that will be allotted to you for the five hours of instructions. You will need classroom space or at least a couple of picnic tables as well as casting space and a pond. Also. there was an minimum age limit required (10yrs old) and each kid had to be accompanied by a parent or supervising adult.