Tamlynne,
We ended up homeschooling my gifted/AS son, now 14, in part so that he could work on social skills and academics separately, and in appropriate settings. An emotionally disturbed class is not the appropriate setting for either of those tasks for your son, it seems to me. It does sound like these meltdowns are being triggered specifically by anxiety over missing a question on the "morning work", from what you say, and it further sounds like the aide who is supposed to be helping is NOT improving the situation.
Functional behavioral analysis from a good, qualified, professional might be helpful here, and should absolutely be tried before the school tries to initiate a change in placement triggered by behavior related to his disability, which this most certainly is.
From my own experiences with my own son, who may be significantly different than yours, I don't think that "This is a great paper!" would be very reassuring to him in these circumstances. He knows that he made a mistake, and he is upset over it. Even though a 90% is still a "good" grade from your perspective, he doesn't have the same perspective you do, and it still emphasizes that the "goodness" comes from having right answers. For you to praise the work with the mistake anyway may be confusing and may make him wonder if he is really capable (since he is being praised for getting something wrong), or wonder why you are "lying" to him, both of which could increase his anxiety over this. No blame here, for sure - just a perspective that you might not have considered. I know that it took me a long time to even begin to get a grasp on how my son saw the world and figure out why he reacted to some things the way he did.
My son was only in school (K) for one year, but I still had to work fairly long and hard to get him past the idea that it was okay and not the absolute end of the world to miss answers on a "test" of any variety. In his mind, the point of the test was to be able to get all the answers right, and missing one was no different than missing a hundred. The intensity of the emotion associated with something like this can really be incredible - my son will still occasionally bring up things that he got "wrong" 9 or 10 years ago and complain that the question was worded badly or that the picture should have been larger so that he could see it better or that more than one of the choices was correct or...or...or...
Missing a question is no longer the trauma for him that it was when he was younger (it now just elicits a request for immediate explanation), though he still has some anxiety and perfectionism. It took a while, and quite a bit of explicit discussion of the topic for him to get the idea that the point of tests, quizzes, and other evaluations was at least two-fold: first, to identify areas where you hadn't mastered everything yet and could still learn things, so the teacher would know what to teach you and what you could skip over, and second, to let the teacher know where he or she needed to improve their teaching of topics that had already been covered. Maybe talking about the idea of work as feedback for the teacher might help him reduce some of his anxiety and make him more willing to do the work. Of course, it would be helpful if the school didn't make a big deal over grades, and if he really was allowed to skip over things he knew already - I don't know how realistic that is.
I would definitely insist that he not be discriminated against in provision of gifted services on the basis of his disability, and that the AS-driven behaviors be recognized as such, and dealt with appropriately using a plan developed after functional behavioral analysis and included in his IEP. The plan should include instruction for his teacher(s) and aide(s) on how to minimize triggering and reinforcing these behaviors, and should include explicit instruction for your son on alternative coping skills for dealing with stressful situations, including things like self-talk, deep breathing, requesting to go to a quiet place (which should be granted), squeezing a squishy ball (if he finds that calming),etc.
Feel free to PM me if you want to.
Best of luck on your journey.
