JenSMP -
Most Achievement tests don't help with school placement. They are more about comparing kids to other kids in various areas than helping teachers know what to do with kids. The MAP is an exception, and I would certianly suggest that the guidance counselor try and set that up.

I think that curriculum compacting is going to give you your actual answer. In this he 'pre-tests' each new subject and only has to go through the actual material if he get's less than a 80%.

More about this in the book http://www.amazon.com/Developing-Math-Talent-Educating-Advanced/dp/1593631596#reader_1593631596

they call it the Diagnostic testing - Prescriptive Instruction Model.

It's not an exact science - someone who knows the curriculum well and has an open mind needs to sit down with him and ask him lots of questions and observe his thought process.

If it's Math - try Aleks.com's free asessment.

Best Wishes,
Grinity


Coaching available, at SchoolSuccessSolutions.com