New York Mayor Bill de Blasio said Monday that he plans to welcome 700,000 students back to school buildings for in-person instruction for the start of the academic year in September, an extraordinary announcement that comes while other big cities plan for remote learning as the pandemic continues to rack the nation.

The city is home to the nation’s largest public school system, serving more than a million children, and is being closely watched by education leaders as it prepares to open its doors. Under the plan, approved by the state this week, students who opted for in-person instruction will still do much of their learning virtually and will only head to classrooms on certain days to prevent crowding in classrooms and hallways.

The city asked parents if they wanted to send their children back into school buildings for a “hybrid” schedule of in-person and online learning. The overwhelming majority said yes.

The United Federation of Teachers, which represents thousands of the city’s educators, has protested the plan, saying it still does not have enough assurances that it will be safe for students and staff to use school buildings.

“Parents and teachers must be confident that schools are safe before they can reopen,” UFT President Michael Mulgrew said in a statement posted on Twitter. “In New York City that is still an open question.”

De Blasio’s announcement comes as outbreaks of the novel coronavirus have thrown some school systems into chaos. Several school systems in Georgia, where Gov. Brian Kemp (R) has barred cities from establishing their own virus restrictions, opened last week. The state’s largest school system, in Gwinnett County, was forced to send 260 teachers home — either because they had tested positive for the virus or were exposed to someone who tested positive. Another Georgia high school came under scrutiny after students posted photos of hallways packed with people. Administrators attempted to punish the students who shared the images — and then shuttered the school for cleaning after nine people at the school tested positive.

De Blasio (D) said he understands why what’s happening in other places could cause trepidation in New York. But he said the city’s virus-related restrictions have paid off.

“Now you look around the country, you see a challenging situation,” De Blasio said during a news conference on Monday. “New York City is different . . . and we’re ready.”

The announcement marks a major milestone for a city that was once an epicenter of the pandemic, with infections in the densely populated city spreading easily. The virus claimed the lives of several educators and other school employees in New York City, though it was unclear how many of them contracted the virus via the schools, which closed in March. More than 200,000 New Yorkers were infected and 22,000 died.

But the city has made strides in recent weeks, with the number of new cases falling by half. On Monday, the city embarked on a new phase of reopening. Subway service returned to normal and hundreds of thousands of people in retail, manufacturing and construction were permitted to return to their jobs.