From the Los Angeles Unified School District website, SAS stands for "Schools for Advanced Studies". It is part of the Gifted/Talented Program ("GATE").
You can read more about it online here: http://sfpc.lausd.k12.ca.us/gate/prog-opt-2.html
Dearborn Street Elementary School is listed as a program participant, located in District 1. View the Dearborn Street Elementary School on the list here: http://sfpc.lausd.k12.ca.us/gate/prog-opt-3.html#ProgOptPg3SAS
We hope that is helpful.