Chicago (CBS) — The Chicago Teachers Union says they have reached a tentative agreement with UNO/Acero Charter Schools’ management, potentially ending the nation’s first ever charter school strike.

CTU says the tentative agreement was reached early Sunday morning. It will align pay for educators and paraprofessionals with Chicago Public Schools’ pay scale, reduce class sizes, and include sanctuary protection for students and families in Acero schools.

More than 500 CTU members have been on strike since Tuesday. Picketers have held rallies at all of Acero’s 15 schools and marched into Alderman Ed Burke’s office on the southwest side on Friday.

The agreement is still required to be reviewed and approved by the CTU membership board.