I would stay away from certain flies for beginners, starting with either the Adams or Parachute Adams. I just think that two hackles are much too difficult to deal with when you are struggling with one. They used to always start beginners with the Adams and I never understood it.
These days a lot of classes start with the Wooly Bugger and guess that's OK. I might start even more simply than that, maybe just a fly with palmered hackle like the old bivisibles or the British Soldier Palmer. Someone said Griffith's Gnat, even better. Then the Bugger, once you could wind hackle.
Everyone forgets that a real beginner has trouble winding thread around the hook reliably. I just don't think you can throw too much at someone right away. Some of the flies mentioned incorporate too many skills in one fly. I like Al Campbell's approach in his beginner series. He starts with a nymph that is basically pheasant tail wound around a hook (not the real Pheasant Tail Nymph that's more complicated) . I myself was thinking of an old English dry fly I used to fish that had a tail made of some pheasant tail fibers, the butts wound around the hook, and a brown hackle collar at the front. It was called the Pheasant Tail curiously enough, and is, I think, a good beginner fly. I caught a fish on it too.
Sit down with someone who has never tied a fly in their life, and you'll see what I'm getting at. Once they get some basics though, the sky's the limit.
Eric