CHICAGO (CBS) — Teachers and staff for the Aspira charter school network said they plan to go on strike on March 17, if they can’t reach agreement with management on a new contract.

If the approximately 100 teachers and staff at four Aspira schools do walk out, it would be the first teachers’ strike for any charter school network in the nation.

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Marines Martinez, a social studies teacher at Aspira’s Antonia Pantoja High School, and acting teachers’ union president, said Aspira essentially has proposed pay freezes and cuts by having teachers pay more into pensions and insurance.

“The last thing we want is a strike. That is the very last thing we want. It’s just that Aspira has not been negotiating with us fairly, and we want to make sure that we put pressure on Aspira,” she said.

Aspira board chairman Fernando Grillo said a pay raise always has been included in management proposals, and a deal could be done today.

“This isn’t a chess game. This is the lives of children we’re dealing with here,” he said.

The union did seem optimistic about Aspira’s latest offer, which was given to them Monday night.

The teachers’ own most recent contract demands included a 3.25 percent salary increase in the first year, and a 3 percent increase in the second year. If not given more money, they want to be compensated with shorter days and a shorter school year for staff.

The Aspira board said its counter-offer is reasonable, even in light of state funding cuts.

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“That school funding problem manifests itself with the deficit that Chicago Public Schools have; and as a result of that, that gets passed down to us,” Grillo said. “Not once have we cut instruction positions, teaching positions.”

Martinez said Aspria teachers make far less than those at traditional CPS schools.

“One comparison that we did make was teacher at Aspira with a master’s, working at Aspira for seven years, was making the same as a teacher who just came out of college first year at CPS,” she said.

There have been a lot of charges and counter-charges between teachers and management regarding available money, pay raises, the pace of negotiations, and overhead costs.

“The reason there isn’t any money is because they spend more on their managers,” Martinez said.

Grillo said Aspira is focused on its four schools.

“So whatever is represented in our administrative ranks, it is an investment in accountability,” Grillo said.

Approximately 1,400 students attend the four schools in the Aspira charter school network.

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The union has planned a rally for Thursday evening, right before the next bargaining session.