"The state law was designed to disrupt that and say, 'This can't continue, this isn't professional for teachers to be treated this way,'" Knowles said.
Chicago Public Schools and the teachers union had settled in March on having student growth on tests and other goals count as 25 percent of a teacher's evaluation in the upcoming school year, down from the district's proposal of 45 percent. Months later, though, those numbers and the timeline for implementation are still being disputed and are part of what is keeping negotiations rolling past deadline.
Knowles said basing 25 percent of teacher evaluations on standardized tests would actually be modest compared to some other parts of the country. In Florida, for example, 50 percent of teacher evaluations this year will be based on student growth.
Florida was also the site of an education showdown that focused largely on teacher evaluations back in 2010. After protests and teacher walkouts, then-Gov. Charlie Crist vetoed a bill that would have made 50 percent of teacher appraisals based on student growth on standardized tests. He won the support of teachers but ultimately lost the election. When Republican Gov. Rick Scott took office in 2011 the legislature passed a similar bill and this time it was signed into law.
Teachers aren't entirely opposed to changing how they are evaluated, said Randi Weingarten, president of the American Federation of Teachers, the nation's second largest teachers union.
"What the Chicago Teachers Union is doing is what teacher unions across the country have tried to do, which is be very open to new evaluation systems but wanting them to be reliable and about continuous improvement as opposed to about narrowing curriculum and fixated on testing," she said.
How much the reforms factor into Obama's votes among teachers in November is yet to be seen. Teachers will be deciding between a Democrat who supports education reforms his party typically hasn't or Romney, who described teachers Monday as turning their backs against students and supports many of the same reform ideas, such as teacher evaluations based on growth and expanding charter schools.
"I think most labor union members and organizers are going to see the forest from the trees and they are going to do what they can to support Obama," Knowles said.
Associated Press reporter Sophia Tareen in Chicago contributed to this report.
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