Yes, Firstly, I think it's great that you're going the extra mile to support his interest in being in a class. You are awesome. I have only worked with special needs people aged 5-25 and in classes filled with mostly special needs people, so take my experience and advice with a grain of salt. I assume from your intro that they are mid/high functioning, streamlined in a regular class and the class is willing to slow things down every once a while to accomplish some basic work refresh (or can be persuaded to if you split up the class and switch.) While there are a million ways try to get him to connect in class I would first start by talking to him, his friends and family to see if he is happy with his progress. I say this because no amount of class coaching will be very effective if he is happy with where he is at in the class and his role in it. Hell, in the worst case, improv may not even be his thing, he just wanted to take a theatre like class and his "thing" is memorizing and reciting sonnets. (In that case he could start and ends the showcase with a sonnet that fits in with your theme and he'll have practice time in front of his peers and an audience, etc etc) If he is happy where he is there is still hope it it's just going to include more involvement on your part. ( I have only had one student that I can remember who was like this so I won't go into much detail if this is the case, and move onto-)

If he is unhappy or maybe unsure of what you're asking of him it's best to assure him that every thing is cool and safe and you just wanted to touch base. This is when I would take the time in class to discuss scenes and try only one new game every day. I'll get to that later.

During the scene discussion I would use more detail and time than you normally would and use a set formula of questions. I would only do this once or twice a night talking about what worked in his scene, who seemed the most connected and why, what needed fixing ( pacing, eye contact, agreeing.) I would also do this with scenes he payed close attention to, and/or visibly enjoyed. I would be careful about opening comments up to people who are less than supportive of his role in the class. I wouldn't shelter him but everyone should feel safe, of course. As scene work progresses I would start focusing in on the things that were pinpointed as needing to be fixed. For example, use a new game that focus on body language vs. speech if he's having trouble maintaining connection with people. Move scenes quickly to new "pop" locations, if he is finding it hard to maintain long scenes with beginning, middle and ends without falters. If he has a favorite game, work back to it if he is experiencing difficulty in another game. For example: I think the scene would have played lighter if you made more of an effort to be inventive like you did in the amazing scene you did last week about the fish bowl space helmet.

Not everyone agrees with this next thing I do and it's not something that works for every person and almost never works with a classroom of similarly abled people. (Goodness, I just felt my name get listed as an asshat on tumbler.) Ok. I find stopping scenes if the special needs actor is having trouble is just fine. It's a last resort but if done in a caring and quick manner, bringing other students up to help or calling back to one of the discussion questions (I have 5 set questions/skills and my first 5 classes work on each one individually so I usually genteelly remind everyone of the number "rule" we should be focusing on, as it seems to help focus the problem into a "solving moment" and helps the actor to self correct.) I know, I hate me when I do it but for some people and especially kids, it works with my teaching style, which is usually very hands on because of the nature of the kids, and varying special needs. I asked one of my really high functioning adults why it helped him, because I was surprised that it did and he said something like it grounded him from all the stimuli that was happening. Another reason why I try to only introduce one new game a night. Lots of structure with the class is good and even helps the actors know when to be creative, if that makes sense.

It's late and a million other things are swimming in my head to try and help you out but I think I'm too tired to explain them fully at the moment. I hope this helps as a start as special needs improv is very wonderful and I've seen it work like magic. Don't sweat it, either. Try everything and only keep what works for your class for that minute but keep trying.