taught me to cast in the late 50's when I was 8, but I watched him cast for a few years before that. I learned on a 9' 5wt bambo set-up on the Quinny, thats all we had at the time.... it worked. Front yard practice came later with my older brother as a warm-up to opening day. As I got older Dad bought more fly rigs, but always 5-6 wt, 9'. He knew a good thing when he fished it. We used those rods for everything. Trout, Bass, Pickerel, Kivvers (Suns) Perch.
I have since taught both my kids to cast with 9' 5wts. They both picked it up in about 1 hour, but I used the local grade school first before going to the river. Now they don't even think about it, comes natural, we just hold up the fish and hoot at each other up and down the river.
Kids adapt pretty easy. I dont think you need any fancy equipment unless they are real young.