My understanding also of the WJ-III math fluency is that it tests speed of calculations, not necessarily knowledge...so I don't know if that's from lack of a disciplined math curriculum at school or something in the brain.

All the more reason to check it out.

Anyway it's very interesting reading about the school math experiences of other kids this age, as in what they're learning and whether or not they're being challenged...and it's not very encouraging unfortunately.