While the KeyMath is a good comprehensive math assessment, it will not give grade equivalents that are any better psychometrically than the WIAT and WJ, which he has already had. All three tests generate normative data, not true grade placement information. The KeyMath will point out specific skill deficits or peaks, but will not tell you where in the curriculum he should be instructed. For that, you need curriculum-based assessment, using summative (end of unit) and formative (progress monitoring and pretesting) assessments from the curriculum itself.
For us, though, KeyMath served well to guide the school where to start with a curriculum-based assessment. The list of topics that DD knew (and didn't know) was also cast in a way that was very much more understandable to the teachers involved, who by reason of NCLB, are terrified of gaps.
