ADD is an old term; the current term for all types is ADHD, with three subtypes.
ADHD predominantly inattentive type: (ADHD-I)
ADHD predominantly hyperactive-impulsive type: (ADHD-HI)
ADHD combined type: (ADHD-C)
http://www.help4adhd.org/en/about/what/WWK1
If hyperactivity isn't an issue than they may be thinking of ADHD-I; though hyperactivity doesn't necessarily show up as getting up and moving around--sometimes it's being excessively chatty.
Perhaps you should push for a more general psychoeducational testing, instead; if you are able to do it privately I wold do that as well. Though it may ultimately lead to an ADHD diagnosis, the results may also/instead indicate a very bright child who may not be challenged in school and/or a "quiet" learning disability. My ds' psychiatrist diagnosed ADHD immediately, but the psycho-educational testing at the children's hospital gave us a lot more information to work with as to how ds' learned and what his strengths and weakness are--such as a more than 15pt gap in what ds understands visually vs. what understands verbally (they also confirmed the ADHD diagnosis, and that he is possibly Asperger's as well).
Did they say why they wanted to do the evaluation? Perhaps they did some "standardized" testing and found he performed better on those than he typically does in the classroom?
I also suggest a visit to the optometrist if he hasn't been this school year; I was several months into 7th grade before I realized that it wasn't that I couldn't understand what was on the board, but that I couldn't see it clearly
. Dh was a bit different in that he had a significant drop in grades before his eyesight deterioration was discovered.
What is Executive Function?
Language & Math