CHAMPAIGN, Ill. (AP) — Graduate student workers at the University of Illinois have gone on strike after 11 months of unsuccessful talks with administrators on a new contract.

Picket lines started Monday morning on the Urbana-Champaign campus, with a few hundred people gathering for a midday rally. The (Champaign) News-Gazette reports some undergraduate classes were canceled or moved to buildings away from picketing.

University spokeswoman Robin Kaler said administrators didn’t immediately know how many classes had been canceled.

Graduate Employees Organization co-president Gus Wood says daylong talks Sunday with administrators resulted in “absolutely no movement.” The group represents about 2,700 graduate students who teach many undergraduate classes.

The group says it wants protection for tuition waivers provided to many graduate students. The university says it has made “generous and serious proposals” addressing those concerns.