CHICAGO (CBS) — After nine school days on the picket lines, striking teachers at four Chicago charter schools have reached a tentative agreement with management, and will return to class on Tuesday.

The proposed four-year deal for teachers at Chicago International Charter Schools would increase pay about 35 percent over the length of the contract, reduce class sizes and protect counselors and social workers.

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The agreement raises teacher and paraprofessional pay to CPS standards, and a new salary schedule includes extra pay lanes for teachers with advanced degrees.

Class sizes would be capped at 30 students, with a goal of 28 students per classroom.

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CICS also would pick up seven percent of teachers’ pension contributions, and provide one week of paid maternity and paternity leave.

Nearly 200 CICS teachers walked of the job on Feb. 5. While they were on strike, principals and non-union staff at CICS led online learning activities for students.

Union members must still vote to ratify the deal.

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This was the second charter school teachers’ strike in Chicago since December, when teachers at Acero staged the nation’s first charter school strike, which lasted four school days before a deal was reached.