Students arrive at Stuyvesant High School in New York City in October.
CNN  — 

New York City’s public high schools will reopen for in-person learning on March 22, Mayor Bill de Blasio said Monday.

The city’s high schools are the final group within the largest school district in the country to be welcomed back to school buildings.

“We are ready to go, we have all the pieces we need to bring high school back, and bring it back strong, and of course to bring it back safely,” de Blasio said at news conference.

There are about 55,000 students in grades nine to 12 and 17,000 staff members returning, according to the city Department of Education.

The students returning had previously opted for in-person learning.

All of the city’s 488 high schools will reopen, and about half of them will have all or most of their students in class five days a week. The education department said that number will continue to increase.

Meisha Ross Porter, the city’s new education chancellor, said it was a priority to get high schoolers back in school for in-person learning and she is “thrilled” to be making good on that promise

Teachers will return to schools March 18 to prepare classrooms, she said.

New York’s public schools have a .57% Covid positivity rate, Porter said, adding that “our schools are the safest place to be.”

Middle school students returned for in-person learning on February 25, while elementary school students returned in the fall.

Two key factors fueled the push to reopen school for younger age groups earlier: Younger children have struggled the most with online learning, and younger students appear to have the lowest rate of coronavirus spread.

De Blasio said children have experienced great emotional turmoil over the last year because of school closures. “Think about the children we’ve lost to suicide,” he said.

“There’s so many reasons that we need to bring our kids back … I want this to be loud and clear, we are bringing our schools back fully in September, period.”

The US Centers for Disease Control and Prevention recently released guidelines for reopening schools that focus on five key Covid-19 mitigation strategies: the universal and correct wearing of masks; physical distancing; washing hands; cleaning facilities and improving ventilation; and contact tracing, isolation and quarantine.

School sports will return in April

The city’s Public Schools Athletic League will return in the beginning of April.

“We are ready to go, we have all the pieces we need to bring HS back, and bring it back strong, and of course to bring it back safely,” de Blasio said.

“All sports” will also return with “strict safety protocols,” and be brought back in phases in April “to make sure it’s done safely,” he said.

Their will be a “heavy emphasis” on moving sports outdoors and the seasons will extend into the summer.

Addressing parents, the mayor said “we cant have big crowds, we have to protect everyone, so this is about giving kids a chance to participate.”

To participate in the league, weekly testing and masks will be required and there will be no spectators allowed. The league will be open to both in-person and remote students.

CNN’s Eric Levenson contributed to this report.