CHICAGO – The Chicago Teachers Union issued a 10-day strike notice Wednesday, saying teachers in the nation's third-largest school district are ready to walk off the job for the first time in 25 years.

Union President Karen Lewis said contract talks with the Chicago Board of Education, which have been under way since November, have not yet touched on some issues that teachers are most concerned about, including wages. She said job security and teacher evaluations also are issues.

The notice means the soonest teachers could strike is Sept. 10, but it doesn't mean a strike will definitely happen.