Questions about Adolescent ADD/ADHD.

I am a teacher and I have seen my share of ADD/ADHD kids. One in particular - she had low reading comprehension, so it was sort of a chicken and egg deal. Could she not understand the material so she would wander or did the wandering lead to her 'ADD'? So when is ADD just lack of overall interest in the topic due to comprehension or, just interest?

Also, I told another student to use a tactic I use - I don't have ADD, but I have to pull together and do a lot of different activities as a teacher. I told him to keep a post it list of 'to dos'. Cross them off when done, break down larger tasks into smaller tasks. STICK TO THE LIST. He actually did a little better. Is it this f'ing easy, because these student's accommodations essentially boil down to "hey, pay attention, write that down. Now write that down. Now pay attention. Look over here. Look over here...."