I'm no expert by any means. This is just my personal experience as a MG V/S learner myself, and the father of another. I suppose it's possible that what I'm suggesting is a memory deficit for your son is coming from the perspective of someone who has superior memory and doesn't know it... though if you ask my wife, I'm the one with the memory deficit.
Of course, nearly all my communications with my wife are verbal, and I have clear difficulties remembering verbal information. If you tell me your name, I'll forget it immediately. If I read your name, I'll recall it pretty well. If I write it, I'll never forget it. So clearly, my memory abilities are linked to my VS mode of thinking.
But yeah, multiplication tables and spelling were things I excelled in. We learned multiplication tables in 3rd grade, in a self-paced manner, and I mastered them long before any of my classmates. That same year I won the school spelling bee, and only lost at the district level because I got over-confident and tripped over my own tongue. When I'd spell a word, I'd see it in my mind, and read off the letters. If I was writing and I misspelled a word, I'd usually notice, because something about it didn't
look right.
Earlier I mentioned how you probably have an idea of your son's memory abilities already from direct observation. People used to use the words "photographic memory" around me at a young age, and now they're using them with my DD. At 18-24mo, she became the family finder. If we had lost something, she'd remember seeing it somewhere, even if she hadn't had any access to that location for weeks. My understanding of VS learners is that this is a typical behavior, because of the nature of storing memories as visual information. I may be wrong again, because all of this is coming from my own (perhaps flawed) perspective.
