J.S.
You need to request a Planning and Placement Team Meeting aka a PPT. When you're there, you need to request that they do the neuro-psych evaluation. It will be free. If you have the official diagnosis from your child's pediatric neurologist, that would help you greatly.
The goal is to get either an IEP (Individualized Education Plan) or a 504 Plan. Either of these education plans would REQUIRE the school to make accommodations for your child so that he gets his free and appropriate education. The fact that he has ADD means that he technically has a disability according to Federal Law, which means he's entitled to certain benefits under the IDEA Act (The Individuals with Disabilities Education Act).
http://www.ncld.org/parents-child-disabilities/idea-guide