Nate - the National Assistive Technology in Education Network brings together information from the many fields and disciplines that are involved in assistive technology services in educational settings.
One key resource we would direct you to is the AT Research section of the NATE website. "Research has many benefits. It can help guide our decision making about AT for an individual student. It can help us determine what appropriate goals might be for a student’s use of AT and reasonable criteria for success. Additionally, basing AT decisions on research helps comply with IDEA. IDEA requires us to use peer reviewed research as much as possible when selecting interventions to help a child advance appropriately toward attaining annual goals."