I was in the intuitives zone and trying to figure out the bridging between how I understood things and to explain/codify it as a pre-teen eventually became a career defining process.
The path I'd suggest is to separate the two elements even further apart. Rather than him explain or challenge him on any particular problem, I'd look for him to instruct you in how to solve a problem. That external need can sometimes sharpen the introspective skills. I also think strategy games may help because they often require projecting specific thought processes onto another person.
DS7 is in a different category as he gets very positive remarks about how well he'll explain math.
