Updated 09/17/12 – 11:15 a.m.

LAKE FOREST, Ill. (CBS) — Teachers in north suburban Lake Forest are meeting with school district leaders Monday morning to try to hammer out a contract. Meantime, Lake Forest High School students were back in class, despite the fact teachers have been on strike since Wednesday.

CBS 2’s Courtney Gousman reports school board members in Lake Forest have decided to resume classes led by substitute teachers and school administrators, while teachers are out on strike.

Meantime, the Lake Forest Education Association labor union and the Lake Forest Community High School District board went back to the negotiating table at 9 a.m., in hopes of reaching a compromise.

There are 150 teachers that work at Lake Forest High School, and they’ve been on strike since Sept. 12.

LISTEN: WBBM Newsradio’s Bernie Tafoya reports

The biggest sticking points in contract talks in Lake Forest have been a two-tiered salary system for teachers, and benefits.

Teachers have said they accepted a pay freeze last year due to the down economy, and now they say the school board is trying to lock in those sacrifices by creating a two-tiered system of hiring, in which new teachers won’t be paid at the same rate as current employees.

About 80 Lake Forest teachers earn more than $100,000 a year, in a town with a median household income that’s about twice that. But union spokesman Chuck Gress said the new hires start at $50,000, and have much less opportunity for big pay raises.

As negotiators were trying to hammer out a deal Monday morning, Lake Forest High School students were back in class, after crossing a picket line outside the school.

Sophomore Sarah Porter said, “I think it’s just gotten kind of old by this point. Like, we had our three days off and that was fun, but now since we’re at school, we might as well be learning something.”

Another student speaking to CBS 2 gave the day’s activities a poor review. She said none of her regular classes were held and there was little instruction. Many students were not paying attention, she said.

School Board President Sharon Golan said, “We’ve got a full day of instruction in all the key content areas.”

Golan said 70 substitute teachers, and a number of assistants, and even parents are on hand to help students get back to learning.

Professional guest speakers have also been brought in to address students.

Golan said the move to resume classes came at parents’ request.

“They have asked that we keep the schools open, but [they] also asked that we hold the line in terms of financial demands. Our numbers are real. We feel that the demands are unrealistic,” she said.

Golan said union teachers are asking for a 5 to 6 percent pay raise per year.

Union leaders wouldn’t talk numbers, but said it’s time to make up for last year’s pay freeze.

“We will be fair and we are willing to compromise, so that we can get this deal accomplished and get our kids back to school,” Gress said.

The regional superintendent planned to be on hand at the high school, to be sure that attendance and curriculum requirements are met, in order for Monday to count as an official school day.

Striking teachers said they plan to stay on the picket until 3:30 p.m. Monday, as negotiations continue.