I have the same question as Alexsmom - did she count it wrong even though the answer itself was right?? I would definitely have a problem with that. To me, that goes above just coping. I can see dealing with the detailed picky stuff, yes, but getting correct answers marked wrong is not acceptable, imo. DS is very concerned with right/wrong & I can see that really bothering him too.

Can you have a chat with the teacher to figure out her expectations for the work?