I would at least go over her head to the Principal (or subject supervisor). Take examples of what your child is doing at home, explain how upset your child is by the homework being given, and make it clear that you will not have your child do busy work that has no point, nor will you have your child do extra work (the regular homework plus additional work).
My DS's second grade teacher pulled the same thing. After several discussions with her that got us no where (she started sending extra work home with him, so he now had twice as much homework, and none of it was at the right level), I told him he didn't have to do any of it. He is too much of a rule follower and was afraid to not do his homework, but at that point I went to the Principal and started down the path to subject acceleration.
Of course, if the homework only takes 2 minutes and isn't upsetting him, it may not be worth the discussion (although I would argue it may be worth it, since it appears this teacher has absolutely no clue).
