Chicago public school teachers walk a picket line outside Lane Tech High School on Tuesday, Sept. 11, 2012, on the second day of a strike in the nation's third-largest school district. Negotiations by the two sides failed to come to an agreement Monday in a bitter contract dispute over evaluations and job security. (AP Photo/Robert Ray)
Chicago public school teachers walk a picket line outside Lane Tech High School on Tuesday, Sept. 11, 2012, on the second day of a strike in the nation's third-largest school district. Negotiations by the two sides failed to come to an agreement Monday in a bitter contract dispute over evaluations and job security. (AP Photo/Robert Ray)
