FWIW my dh is an art professor and I ran this one by him. We are currently on the road so couldn't access the image. He related the stories of a couple of his current students, one of whom is actually an art minor. No matter how hard they try these students simply lack the ability to *see* some of the specific techniques he is teaching them. As he put it something gets lost as the image is taken in by their eyes, or as it is translated to their brains or as it is transferred from their brains to their hands. It doesn't matter how hard they try there are certain things they simply cannot do. In a Drawing class where they are graded on their grasp of certain techniques their inability to satisfactorily do the work affects their grades. However if this is not a Drawing class and certain techniques are not required it's a different situation. Just as his students get credit for the effort they put in it seems that your ds's stick figures do not necessarily mean a lack of effort just because his end result is different from other kids in the class.

He has an IEP right? Is it because of dysgraphia? If so it may mean this teacher is saying she plans to penalize him for his disability. If this is not related to his disability it could still be his chosen artistic style. If it's the former I would be looking att making a major fuss. If it's the latter I think your choice outlined above is something for him to consider. If it's really just a matter of him lacking effort the teacher may have picked up on a legitimate issue. Are you able to decipher which it may be?