They do some differentiation in the classroom, but it's not really adequate to her needs. I volunteer in the classroom once a week at their literacy centers, so I can see the contrast first-hand--for example, I just went over today to help out at the table where the kids were writing stories based on sequencing cards. DD filled her page with a detailed, complex story that explored the emotions and motivations of the people on the cards and then moved on to the next one, while her classmates, even the higher achieving ones, wrote short, descriptive sentences. When she watches a movie, she immediately compares it to other ones she's watched ("Moana" is just like "Frozen" because XYZ") and explains its structure ("this is the montage", "this is the scary part, but I know it's going to be okay because it's just the climax").
We often talk about history; she remembers literally everything I tell her and makes connections between Marie Antoinette and Anne Boleyn. She comes home from school disgusted that her classmates don't know that there were no cars in George Washington's time. And so on.
The issue is that I just don't know what to do with a kid who's clearly bright but not anywhere near profoundly gifted and yet does seem to have noteworthy abilities in the humanities. Would jumping her up to 3rd or even 4th grade reading and writing even address the underlying problem? I don't want her to spend elementary school identifying main characters in slightly more difficult books.
As far as working memory and math, you may well be right. My understanding is that working relates strongly to the ability to recognize and use patterns, so it seems likely that there would be a correlation between strengths in both areas. It may be worth having her tested in again in a few years and see if her abilities even out in either direction.
