Brainstorm:
Since the parents are in the classroom every week already, can you get them to work with a group of you 'best students' while their son is doing something else? Let them try to teach a bit, and there is a chance that that will thaw their denial a bit.
Do BOTH parents volunteer in the classroom? That would be unusual in my son's school, and I'll bet it isn't the norm where you live either. If so I'll take a wild guess and say that they probably believe, as I once did, that their son is doing so well academically because they are such involved and loving parents. ((shrug))
Another idea is to have a meeting with the parents to learn from them what the tester suggests for school modifications. Letting them tell you might be just the thing.
Smiles,
Grinity
