I was thinking more along the lines of hothousing the skill in a non test specific way - setting up Adults that you know and trust (at least minimally) for him to practice talking to.
Some kids only need the parent to tell them what to do and why. My kid was the opposite. He needed to practice the behavior and have me notice and praise what was working. What are some real world activities that involve him explaining his thinking to strange adults? Does he have a favorite topic that he could be an expert helper to folks on?
