Teachers from District 300 in Carpentersville are on strike.
The district covers more than 20 schools in communities that include Carpentersville, Dundee, Barrington Hills, Algonquin and Lake in the Hills.
Teachers union leaders say they were unable to reach an agreement with the school district. The sticking points are compensation and class size.
On Monday evening, striking teachers worked on signs they plan to carry Tuesday morning. Many expressed a strike is not what they want.
"We tried to do whatever we could to avoid this," said Mike Williamson, teachers union spokesperson.
The district believes the school board has tried to reach a resolution.
"I can speak for the entire board saying none of us believe that it is the appropriate time in this terrible economy to go to our taxpayers and ask them for more money. That's not going to happen," said Joe Stevens with the school board.
ABC7 is told union leaders have asked to meet with the board's negotiators Tuesday. It is not clear if that will happen.
Parents picked up students from various activities at Jacobs High School Monday evening. Most said they are hoping for a quick resolution.
"They're teaching our kids... That's who loses. The kids," said parent Carri Helton.
"If it goes too long, it's going to push finals back and that's going to start affecting me," said student Taylor Brust.
