Our 5 year old is also very strong in math. We recently had him tested with the SBV and the Woodcock Johnson - III. We don't have the final results for him, but everything correlated well with what we thought about his skills. I have previously communicated with the Center for Talented Youth (CTY) staff at Hopkins about how to have him tested; they are well known for their work with gifted kids, particularly in the math area -- they started the "original" above grade level talent search. This started in the 70s as the "Study for Mathematically Precocious Youths"; the original premise is that boys and girls take the same math classes (in general, and more at that time) through middle school, starting differentiation in high school, so if you test kids at 7th grade, you may see what sort of differences there really are between the genders. Anyway, their team suggested the KeyMath3, because of its thoroughness in evaluating different mathematical skills. We ended up with the WJ-III because as it turns out, it isn't so easy to find someone who actually knows and uses the KeyMath3. If we ultimately test him further, we will probably go up to Hopkins to do specific math testing.
The SBV and WJ-III, though gave us the answers we need right now (that is, he is very very bright, particularly at math, and they /we will need to work harder at keeping him accomodated and challenged, particularly as he gets older). We are sort of feeling our way in accomodation. His teacher is working with him one on one on a 3rd grade math workbook, and we are going to try out the EPGY program, to see if that is something he responds to.
Good luck!! Our son tested great, and he can certainly be a bit timid. Rapport with the tester is important, and make sure that they don't test for too long at once (we did three two hour sessions, which worked out great). DS was very disappointed after the three weeks of testing that he didn't get to go back to see the "puzzle doctor" anymore. He wants to know if 6 year olds can go to the puzzle doctor again...
