I am not an expert on testing either and I have no reference to offer for my opinion. My impression as to which testing might better demonstrate science aptitude is more in the realm of perceptual, abstract and non-verbal reasoning and/or logic rather than information or even verbal reasoning. Aside from measuring a capacity for �connecting the dots� these areas somewhat capture the ability to see 2nd, 3rd, or greater order of effects. We probably all agree that strong logic ability is indicative of systematical and ordered thinking which, of course, is necessary to confirm or disprove initial perceptions.
Science knowledge could be directly accessed through above level achievement testing for that subject. If I was in your place, I would ask to go way up, based your descriptions of your son�s interests. Lower level elementary tests may completely miss his areas of expertise.
