Atlanta Channel 11 (on the net) is still reporting lockdown at some schools and is talking to a school district administrator (Joe ??) now. He is reporting normal classes in remaining schools in lockdown and others no longer on lockdown. You may have some incorrect information -- possibly only some schools are having an inservice day.
Maybe Atlanta is not part of the Fulton County School system. Have no idea since Atlanta is in Fulton County.
My kids are off as are all Fulton County schools. I will link to the Fulton County School calendar showing March 11 as a Teacher Work Day.
http://www.fultonschools.org/addapage.asp?page=media-bin/html/2004-2005Calendars.asp