So my list has five girls(?) named Burwell who attended the Mordecai school:
Eliza Blair Burwell was there for both sessions of 1812.
Lucy Burwell was there for both sessions of 1817.
Martha C. Burwell was there for four sessions, 1811-1812.
Mary W. Burwell was there for both sessions of 1812.
And N. Burwell was on the rolls for 1809.
I have most of these names attached to Mecklenburg County, Virginia, and the adults named Armistead Burwell and Richard Boyd are found in the ledger, paying for their accounts (possibly also William Robards). Martha C. Burwell was married to Grandison Field in November 1816, and is mentioned as "Mrs. Field" in some of the Mordecai letters after that date (for example, 3 July 1831, Caroline Plunkett to Ellen Mordecai, in the Jacob Mordecai Papers at Duke University). So that's where I'm starting from.
I know this is a recurring theme of this blog, but there were a lot of Burwells in the area--and even several Armistead Burwells, all related. One branch of the family even ran a girls' school in Hillsborough NC, in the 1830s. (That linked website for the Burwell school does some of what I'm trying to do here, in listing all the known students and, where possible, their life stories.)
With that in mind, we'll start with the one we know most about: Martha Christian Burwell (b. 1795) was the youngest child of a very large family of Burwells--she was the sixteenth and last child born to Col. Lewis Burwell (1745-1800), who served in the Revolutionary War, and the fourth child born to the second Mrs. Burwell, Elizabeth Harrison (1754-1824). She would have been a five-year-old when her father passed away, and was a teenager during her years at the Mordecai school--seventeen when she left, making her one of the older students. She married Charles Grandison Field in 1816, in Richmond. (His name is sometimes spelled Feild or Fields or Feilds, by various branches of the family.) Charles Grandison Field and Martha moved to Tennessee in 1836, with their whole household, including a significant number of slaves. (Among the slaves in that group were the ancestors of Tennessee Assemblymen John Boyd and William A. Feilds.) Martha was widowed in Tennessee, and seems to have remarried at least once. She might have had children, but I can't find mention of their names (she might also have raised step-children). I saw one mention of her dying in 1898, which would mean she was over a hundred years old--possible, but without seeing it mentioned in multiple places I'm not going to assume that's true.
The other Burwell girls couldn't have been Martha's sisters, because all her sisters were older than her and wouldn't have been young enough to attend the Mordecai school. Unfortunately, they all have fairly common names for the Burwell families, and I'm not locating any that are the right age.
Thus end the Bs! Next entry, we move onto the C names.