I agree with Patience, the ability to have the students give even a small amount of eye contact is essential. Having children be able to look at you (or the object) even for a second is progress, and being able to have them comply with a task or simple command is essential. The thing that has worked best for me is being able to have children do things repeatedly and be able to do things without even thinking about it also is a special task. Working with children that are non-verbal it can sometimes be difficult to fully do many assignments as they are written out but with some small tweaking and a lot of verbal support from the adults within the classroom all activities can be implemented and achieved.