One thing to note--the CogAT for grades K-2 is untimed whereas for grades 3 and up it is tightly timed. So a kid with processing speed and/or working memory issues could ace the CogAT in 2nd grade but do poorly on it in 3rd grade.
This was our experience. DD was given the CogAT when she was grade accelerated from K to 1st. I was never given the scores but was told they were fine for the cut-off they needed to accelerate, and that non-verbal was the highest (same as the WISC given later). Fast forward a year and she was given the timed version with half of the questions left blank, and with results in the average range (except for verbal).
