(CNN) New York City Mayor Bill de Blasio said city schools plan to reopen in the fall with a "blended learning" approach in which most students spend just two or three days in school per week.
"At some points in the week, you're learning in person in the classroom, at other points of the week you're learning remotely," he said Wednesday.
"Most schools will not be able to have all their kids in school at the same time," he added.
NYC Schools Chancellor Richard Carranza said the idea of the approach is to lower the number of students in one place at the same time as society adjusts to the coronavirus pandemic.
"We know that we cannot maintain proper physical distancing and have 100% of our students in school buildings five days a week. It's just geographically, physically not possible," he said. "Health and safety requires us to have fewer students in the building at the same time."
New York Gov. Andrew Cuomo acknowledged concerns Wednesday about teachers' safety.
"When we came to the reopening of the economy, I've said I'm not going to put someone in a dangerous situation. There is no money on the planet that can pay for a life as far as I'm concerned, so it's a balance, and the same is with schools," Cuomo said Wednesday.
The announcement, two months before NYC expects to start schools, provides some clarity for students and parents in the largest school system in the country, which teaches over 1.1 million students in over 1,800 schools.
Coronavirus cases are spiking across the country, but not so in New York City, once the epicenter of the pandemic. New York City's reopening has been slow and cautious, and even now indoor seating at bars and restaurants remains closed. It remains to be seen if reopening indoor schools will change those low case totals.
Still, there is apparent widespread support among parents to get kids back in the classroom. At least 75% of parents said they want to send their children back to school in September, de Blasio said last week.
The CDC's guidelines for reopening schools encourage hygiene, the use of cloth face coverings, and staying home when appropriate. It also suggests staggered scheduling, a back-up staffing plan, modified seating layouts to allow social distancing, physical barriers and closing of communal spaces.
De Blasio said that everything will be done with a "high bar" for health and safety and that the city will move forward accordingly with data and science. He said they plan to "put every precaution in place" and "test to see if it's working."
New York State has not decided if schools will be open in September but has asked each of the 700 districts to come up with a plan. Cuomo said the decision to reopen will be made during the first week of August.
De Blasio said the city will continue to work closely with the state on the school plan.
"The only way we're going to be in a position to open schools is if we're in ready position right now actively doing the work. If the data tells us we have to do something different, we will and we'll work with the state very closely on that, but my responsibility is to have the schools ready to go," he said.
De Blasio said students will be learning five days a week, whether it's in person or at home.
"Students will return in September in either a blended learning model or a fully remote learning model if they so choose," he said.
Young people are much less likely to have serious problems due to Covid-19, but they are not immune to the virus, and they can infect other people, including teachers and parents, who may be more susceptible.
"We can make up learning for students," Carranza said. "We cannot bring a student back who is infected and passes away."