Agreed- handedness doesn't determine educational needs. Do you think it has any influence over specific abilities? It's hard for me not to think of it as part of the uniqueness of our DS, as his left-hand dominance was evident at such an early age- we chalked up many of his differences to being a lefty- before we linked them to aptitude.
A lot of the stuff for which Silverman is most famous seems to lack reliable support, including this whole "visual-spatial learner" concept. I see a lot of danger in putting trust in untested concepts like this; it could, for instance, result in someone not working hard enough to find a learning disability, content with the notion that their smart dyslexic child was "just visual-spatial". Silverman appears to buy into a lot of other stuff without solid research support as well, such as multiple intelligences theory and learning styles.
Because of this, I wouldn't ascribe any sort of learning differences to handedness based just on Silverman's speculative and anecdotal writings. And I haven't seen anything else to convince me that, for instance, left-handedness means a parent should look harder at math enrichment or acceleration. Until I see something credible, no, I wouldn't believe in it.
Being left-handed isn't that unusual. Even if there were some small correlation with certain abilities shown someday, you couldn't make decisions regarding a specific child based on that; you'd have to rely on the evidence about that specific child. Here you probably have compelling evidence of a need for gifted math support (PR scores, plus whatever you've seen of his actual math ability) and should proceed based on that, in my opinion. If your child seemed math-average in your day to day perception of him and were happy with average schoolwork in that area, but wrote like Dickens at age 7, it would of course also be foolish to prop him up in math based on something Linda Silverman wrote, while ignoring his other demonstrated talents.
