Photo by: Sitthixay Ditthavong

Thousands of public school teachers rally Sept. 10, 2012, outside the Chicago Public Schools district headquarters on the first day of strike action over teachers' contracts in Chicago. For the first time in a quarter century, Chicago teachers walked out of the classroom, taking a bitter contract dispute over evaluations and job security to the streets of the nation's third-largest city — and to a national audience — less than a week after most schools opened for fall. (Associated Press)