The proposed new teachers contract would undo a key provision of the 2005 contract, which expanded the school week so that teachers could work with small group of students. Now, most of that time would be devoted to teacher professional development and some to parent outreach.

The 2005 contract added an extra two-and-a-half hours, or 150 minutes, to the school week and had most schools divide that into four after-school tutoring or small-group sessions per week. “Multi-session” schools that have staggered starts were allowed to spread those extra minutes throughout their normal school day. Also, schools could request to use some of that time for teacher-team planning rather than tutoring.

The new contract, which must still be ratified, would take back those 150 minutes and split them into three chunks: Teachers would spend 80 minutes each Monday in school-based professional development, 35 minutes on Tuesdays collaborating with colleagues, and 40 minutes each Tuesday communicating with parents in writing, on the phone, or through newsletters and class websites.

Multi-session schools will again be exempt from this default arrangement, though they will be expected to provide professional development and parent engagement, according to union officials. Also, schools that prefer their current arrangement with the extra instructional time could request an exemption that would allow them to keep some part of their schedule.

Teacher committees at each school will help decide how to use this new training time, though a main focus will be on the Common Core and the city will offer schools guidance as they design their training, officials said. At Thursday’s contract deal announcement, Chancellor Carmen Fariña said teachers could spend some of the professional time writing curriculum or sharing best practices.

“This is peer-to-peer, teacher-to-teacher,” she said, “And it really is, to me, a dream come true.”

Some educators embrace the notion, embedded in the contract change, that it is worth sacrificing some instructional time to help teachers improve their practice. But others note that the quality of professional development and collaboration can vary widely from school to school and they question whether taking away teacher time with students will ultimately lead to higher student achievement.

The New York City Parents Union called the change a “travesty” in a statement released Friday.

“Those who highlight the loss of 37.5 minutes per day of instructional time for our children are on target. This contract puts students last and promotes the erosion of time on academic task,” the group said.