DS only has 1 piece of home work a week. Once, the teacher marked 1 math question wrong, DS did it right, but teacher said it was wrong. DS did it with my help, so I can see it is a bit tricky, you may get it wrong in a hurry. So I left it. The other time, teacher missed some part of his homwork which was in another page. Well, I guess teacher must marked it in a hurry. I didn't say anything. But then this time, it's about writing, teacher marked one word wrong, suggested a different word. But I think the one DS used is definitely right, and I asked a few people for confirmation, they all agreed DS was right.
What would you do then, just leave it? Talk to DS, and tell him that he is right, that teacher sometimes do make mistakes? Talk to teacher?