astronomama,

Busy couple of weeks over here, so I'll be back with more detail in a bit, if no one else clears up this point for you to your satisfaction before then...but quick version: the difference between his cognitive and achievement measures is probably not actually statistically significant, or if it is, not as dramatically so as it might appear (see regression to the mean). So not yet cause for panic...That's a different question from whether his needs are being met in school, of course.

...pronounced like the long vowel and first letter of the alphabet...