NEW YORK — High schools will reopen for in-person instruction on March 22, and the city will phase in a return of high school sports beginning next month, Mayor Bill de Blasio and incoming schools chancellor Meisha Porter announced Monday.

"My priority as chancellor is to open, open, open," Porter said. "And I'm thrilled that we are making good on that."

About 55,000 students in grades nine through 12 who have already opted in to in-person learning will be able to attend classes in person, at about 488 high schools across the city. Staff in high schools — about 17,000 employees citywide — will return on March 18 and 19.

About half of high schools will be able to serve all or most of their students five days a week, the city says.

"There's so many reasons we need them to be back where loving, caring adults, trained professionals are there to support them," de Blasio said. "Think about that child that right now is feeling a little helpless and lonely. What is going to mean for them on Monday, March 22, when they walk back through the door of their high school, see their friends, see their teachers and have hope again."

And for the first time since schools shut down last March, the city will allow public high school students to play sports — the Public School Athletic League will return in mid April, the city says, with strength and conditioning. Competitive play will begin in May, and for the first time, will run through the summer.

Students learning remotely will be eligible to play sports in-person, the city says. Weekly testing will be mandatory, as will masks, and spectators will not be allowed.

"All sports, but with strict safety protocols with a phase-in to make sure our student athletes are ready to make sure it's done safely," de Blasio said.

The reopening of high schools comes more than three months after all schools in the city closed in mid-November, as cases of Coronavirus surged.

The city reopened schools in phases, saying that was necessary due to the more intensive coronavirus testing regimen put in place as part of the reopening. Elementary schools reopened in December and middle schools followed in late February.

High schools present more challenges, the mayor and the education department have said, because students typically would have many classes a day with different groups of students. In order to slow the spread of coronavirus, students are no longer changing classes and are grouped into cohorts — but that's much harder to do in high schools because not all students in the same grade take the same courses.

For that reason, many high schoolers had what was essentially a remote experience even when they were in-person — sitting in classrooms or auditoriums but using a laptop or iPad to learn from a teacher who may have been in another room in the same building.

Some high schools are currently being used as vaccination sites. Those sites will be relocated by early April, the DOE says. They'll remain open with their normal hours during spring break, which is March 29 through April 2. Appointments between when schools open on March 22 and when spring break begins on March 29 will be held before or after school hours, or on weekends.