About 1,600 teaching and graduate assistants at the University of Illinois at Chicago who say they struggle to live on the university’s wages declared a strike on Tuesday.

Their union, Graduate Employees Organization, is calling for a salary increase and a waiver of student fees. Anne Kirkner, GEO co-president, said they do the work of professor for a fraction of the wages.

“That’s precisely why they hire so many of us, because we’re cheap labor,” she said.

Kirkner was one of hundreds of students picketing along Halsted Street on the UIC campus Tuesday. She’s a doctorate student in criminology and teaches a criminal justice class of about 60 students. Kirkner said she and other grad students have had to take on second jobs to make ends meet, which can be difficult to balance on top of her own studies.

UIC graduate employees earn a minimum salary of about $18,000 and they receive tuition waivers. They pay about $2,000 a year in general student fees and health insurance costs.

In a statement, the university said the strike is not in the best interest of the school or students, but it respects the rights of the employees. It said it’s committed to continuing normal school operations during the strike. But the union said most classes taught by grad students were canceled Tuesday.

Administrators said they will continue to negotiate with the union. They’ve offered an 11.5 percent raise over three years, compared to a 24 percent increase proposed by the union. The university said it can’t waive fees because it relies on the revenue. The administration also said the current minimum student wage is the equivalent of a $62,000 salary for a 40 hour work week when combined with the value of the tuition waivers.

“You can’t say that to people who are struggling to pay rent, to pay their medical bills,” Kirkner said. “The reality is that we live on $18,000 a year. We don’t see any of that tuition waiver. That’s just money they’re opting not to charge us.”

Chelsea Cox, a graduate student in clinical psychology, walked the picket line with a borrowed orthopedic boot. She said she’s suffering from a stress fracture, and the school’s health insurance didn’t cover the cost.

“The money that we make, unfortunately, doesn’t cover these unexpected accidents that might come up,” she said.

Last year, graduate workers at the Urbana-Champaign campus were on strike for about two weeks before a contract agreement was reached.

The UIC graduate employees have been working without a contract since the end of September.

The next bargaining session is scheduled for Friday.

Susie An covers education for WBEZ. Follow her on Twitter @WBEZeducation and @soosieon.