LAKE FOREST, Ill. (CBS) — Classes are back in session at Lake Forest High School, but the teachers’ strike continues this Tuesday.

As WBBM Newsradio’s Bernie Tafoya reports, contract talks lasted until 11 p.m. Monday, and are supposed to resume in the mid-afternoon.

LISTEN: WBBM Newsradio’s Bernie Tafoya reports

Teachers are in the fifth day of their strike, while students are in the second day of being in school during their strike.

The administration says 1,400 students showed up Monday. There were 70 certified substitute teachers who conducted classes.

More of the same is planned for Tuesday, along with motivational talks and career day talks from people who work in marketing, the law, journalism and pharmacy.

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

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.