Arlington Schools are far superior to those in Fairfax which is also reflected in the fact the Duncan would choose Arlington. Arlington is a small county with 10% of the student body compared to failing Fairfax or Montgomary Counties. Especially, now during these bad times many students in Fairfax are in trailers and teachers are being laid off. Arlington does not have the same problems because of the great wealth of the people living there supporting the public schools. Arlington is the foundation of rich democratic america - just take a drive in Country Club Hills and it is right there to be seen.
It’s difficult (if not silly) to compare schools in Arlington or Falls Church to those in Fairfax or Montgomery. Arlington has all of 3 high schools; Alexandria and Falls church each have 1.
It could be said some Fairfax/Montgomery schools are better than those in Arlington/Alexandria/Falls Church, and some are worse.
Fairfax does, after all, have THE #1 school in the entire country, with a complement of a half-dozen or so Arlington students, 3 from Falls Church, and none from Alexandria.
I would imagine Duncan moved to Arlington because it does have good schools and is very close to DC, not to mention a seriously liberal slant.