Wow - some great ideas above. My thoughts are pretty basic in comparison, just focusing on the practical aspects of how do you start these kinds of conversations. With both my 2E kids, I framed the testing as 'understanding what is easier, and harder, for you to learn, so we can better match you with the kinds of teaching you need'. With results in hand, my lead-in was along the lines of 'we have some information back that really helps understand why you are struggling so much in school right now. School is set up to teach you *this* way, but you need to learn *that* way'.
Note that this equally covers the gifted and LD issues. And a lot of the anxiety arises from that mismatch in the classroom - being asked everyday to do things that seem inexplicably hard, even though (especially because) everyone else seems to do them fine.
For both my 2E kids, a critical part of reducing anxiety was helping them discover and believe that they could do well when taught the way they needed. Admittedly, this was easiest when remediating DD's dyslexia (a long but straightforward process), and a lot harder for less easily-remediable issues, whether other language/ processing deficits, ADHD, anxiety, or lack of gifted peers/ teaching. Sometimes, the only place where they got what they needed was outside the classroom.
With DS especially, we talk a lot about the saying "If you judge a fish by it's ability to climb trees, it will spend its life thinking it is stupid." For my fishy DS whose strengths and weaknesses are the opposite of those demanded by elementary school, sometimes I need to remind him that he is doing great to be working hard on on those branches at all. I need to make sure he spends enough time in the water to truly understand that no, I am not stupid, but yes, I do need to be self-aware enough to understand the difference between the kinds of environments in which I thrive and the kind in which I don't. And recognize that I am not to blame for either, this is just how I am.
