They do, because children with ADD simply cannot function in a chaotic room where expectations and standards are not clear. But a structured classroom can be very deceiving. I know that parents will often look in on a classroom and if it's quiet and all the children are working at their desks, they will conclude that they're looking at a structured room where their child will be successful. You can't judge a room's structure that way because often that's not what we mean by a structured classroom. A casual observer might look at that room and conclude that the structure is not there.
Structure is absolutely there.
That's very difficult. I generally don't recommend that a parent demand a certain room. Even somebody who knows the teachers well, like myself, can find it very hard to predict what teacher will work best for what child. The most important advice for parents is you need to be with a teacher who is open and willing to communicate with you. You need a teacher who is a team player, who wants you as part of the team, who encourages and does everything she can to bring parents into a partnership, who is willing to listen and be flexible.