Today teachers at 243 Chicago Public Schools returned to their job without a contract, and with the possibility that they could stage a district-wide strike.

Chicago Mayor Rahm Emanuel put a happy face on for the first day of school for about one-third of CPS students and teachers, noting the interim longer school day agreement reached between CPS and the Chicago Teachers Union. “It’s a new year for students across Chicago, because now they have a full day and full year of school that matches up to their full potential,” Emanuel said in a statement.

But Wendy Katten, co-founder of the Raise Your Hands coalition of CPS parents, notes that it is impossible for parents to know if their students will continue to attend school as CPS and CTU continue closed door negotiations. “Parents are confused,” Katten says.

According to Katten, part of the confusion is that the deal announced July 24 for a seven-hour school day gave parents a “false sense” that the labor impasse was resolved. “There was too much celebration and parents thought things were going to be fine,” Katten says, noting that Emanuel and CTU President Karen Lewis both held triumphant press conferences on the agreement.

But CTU has made clear throughout contract negotiations that there are many issues that still need to be resolved. These include teacher pay, job security, health benefits, and implementation of a new teacher evaluation process, according to a CTU statement released Thursday.

CTU members authorized a strike June 11. Following the rejection from both CPS and CTU of a third party fact finder’s report, the union may strike anytime after August 20 provided they give CPS a ten-day warning.

Teachers are returning to work under the terms of their former contract that ended June 30, according to CPS spokeswoman Becky Carroll.

Also, the Board of Education gave CPS the authority to temporarily base their spending on a proposed fiscal year 2013 budget, according to Carroll. That budget has come under fire from just about everyone on the political spectrum as it drains the district’s reserve fund.

Rod Estvan, who specializes in education policy at Access Living, says there are no recent examples of CTU teachers working without a contract. CTU has not held a walkout since 1987.

But Estvan notes that teachers at the Zion-Benton School District in Lake County worked until January of the 2011-12 school year without a contract. The approximately 300 teachers in that district worked without a contract from July to January, then staged a four-day strike in January before coming to an agreement.

September 4 will be the first day of school for the majority of CPS schools.