Updated 10/16/12 – 10:47 p.m.

CHICAGO (CBS) — School teachers in Highland Park and Highwood went on strike Tuesday, canceling classes for students in North Shore School District 112.

CBS 2’s Jim Williams reports the two sides resumed negotiations at noon Tuesday and continued late into the night, with both sides hoping to end the strike impacting elementary and middle school students in Highland Park and Highwood.

“The board negotiating team entered the mediation session this evening fully dedicated to the negotiations process. The board presented the union with an improved proposal that showed substantial movement,” according to a statement the district released Tuesday morning.

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The two sides are disagreeing on salary, insurance, and what compensation teachers would receive for continuing education.

The average teacher salary at District 112 is about $70,000, higher than the state average, but teachers have said the district’s salary proposal would make them the lowest paid teachers in Lake County.

The board offered to pay professional growth for teachers who complete graduate coursework, and to pay insurance for part-time teachers on a pro-rated basis.

The board also offered to address the union’s concern about the duration of the contract by eliminating the third year.

All school buildings will be closed on Tuesday; with the exception of the Green Bay Early Childhood Center, Oak Terrace Elementary School, and Northwood Junior High School. Those three buildings will serve as activity centers for children whose families pre-registered last week. About 400 students took advantage of activity sites set-up at at the four schools within the district.

For a list of other alternatives for District 112 students, click here.

Teachers created picket lines in front of several schools within Highland Park and Highwood on Tuesday. Teachers said they would be the lowest paid school district in Lake County if they accept the school board’s latest offer.

Pamela Kramer, president of the North Shore Education Association, said teachers are asking for a 3.25 percent raise, while district officials said they’re offering a 1.5 percent increase. Both sides have been trying to come to an agreement since the spring.

“We believe in getting a fair salary package, fair retirement benefits.” Kramer said. “If we accepted the current offer, it would make the contract in our district one of the worst in Lake County.”

Susan Behn, a teacher at District 112’s Lincoln Elementary School, said, “I think that, in order to order to have the best teachers, you need to have fair compensation. It’s not about any of us getting rich. Nobody goes into teaching to make a lot of money, especially if you’re a second career like I am. We go because we love to do it.”

Fellow Lincoln teacher Larry Patrick said being on strike “is very painful. And it’s nice that we’ve had some support of students, and I know that my heart’s in the classroom. And that’s where I’d like to be. And hopefully negotiations are going to go well tonight, and that’s where we’ll be tomorrow.”

The district would not comment on the progress of Tuesday’s contract talks, or how long the negotiation session would continue.

There are 4,500 students in the district, which serves Highland Park, Highwood, and Fort Sheridan in pre-kindergarten through 8th grades.

“I’ve taught for over 21 years and I’m scared,” said Heather Sinense, a fifth-grade teacher. “It’s not something that I want.”

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