Disagreement with bio mom

Rebecca

So my stepson is 5 and just started his first week of school (terrifying!) I pick little man up on my way home from work on Friday nights and drop him off Sunday after church. since this was his first week at school, I'm just now getting all of his "homework." Finding out that the school wants him to be able to spell and write his name without knowing his letter first is a little mind boggling to me. Since when is this a thing?! I worked with him every time we had him to get ready for school. But every week I would pick him up, he completely forgot everything! I know mom has completely checked out of being a mom but still. I have offered to homeschool him so he doesn't fall behind but mother refuses (if we get more time with him she loses her government assistance.) I don't even know what to do any more. Ladies, please help!