After shutting down last month due to rising cases of the coronavirus, some public schools will begin reopening on Monday.

Which students are heading back? How often will they be in class? And could schools close again? Well, it’s complicated. Here’s what you need to know about Back to School, take two.

Which schools will open?

Pre-K and 3-K centers, and elementary schools serving students through the fifth grade, will open their doors to students on Monday. District 75 schools for students with disabilities will open their doors on Thursday. There’s no date yet for when middle or high schools will resume in-person classes.

There’s one possible exception: schools in the orange zone now covering about half of Staten Island. Mayor de Blasio says he intends to open those schools next week, but can’t say what day they’ll open.

“Next week, we intend to open schools in that orange zone area of Staten Island. We have some additional work to do. We haven’t fixed the date yet. We will do that very quickly, obviously, but we still intend to move forward for next week,” he said Friday.

How many children are going back?

The city estimates about 190,000 children will be eligible to return to classrooms beginning Monday. That’s the number of students who have opted in to blended learning and attend early childhood, elementary and District 75 schools.

Only students who have already opted in to blended learning can return this week. The last chance to do so was during a two-week enrollment period in November. The mayor has said he does not plan on allowing any other families to sign up for in-person learning unless the situation with the coronavirus changes drastically, such as a vaccine being approved.

Will all special needs students be able to return?

Not necessarily. District 75 serves the students with the most significant special needs, and those schools will reopen on Thursday across all grade levels.

But many other students who have an Individualized Education Program, or IEP, attend schools that are not part of District 75. If those students are in middle or high school, they won’t be going back to class next week. If they’re in elementary school and they signed up for blended learning, they will be able to return beginning Monday.

How many days a week will students attend in person?

The short answer is: it depends.

The mayor says the city’s goal is to move to five-day-a-week instruction wherever possible, and he believes that will be possible at most schools. That’s because so fewer children signed up for blended learning than expected, allowing those students to attend more often than planned.

For example, let’s say a school was expecting 14 students in a class to attend in person. To maintain social distancing, that class has to be split into two cohorts of students, A and B, who alternate days attending in person and at home.

But in reality, only three kids from Cohort A have been attending, and five kids from Cohort B. In that case, the school can combine those two cohorts into one group of eight children who can attend every day.

The mayor says he believes this will be possible at most schools in the city because of how many children have chosen to learn remotely and not return to classrooms. Many students who signed up for blended learning have not actually been attending, instead learning remotely. The mayor says if those kids don’t show up this week, they’ll be removed from blended learning altogether to make more space for students who are showing up. And the in-person enrollment could shrink further if some families refuse to allow their children to be tested for coronavirus, which is now a requirement to attend.

Still, the union representing school principals has questioned whether it will really be a majority of schools that can move to five days a week. While enrollment is lower citywide than expected, it is still quite high at some schools, and others say they don’t have enough staff to make daily classes work.

If a school can’t provide all of its students with five-day-a-week instruction, the city has instructed them to attempt to offer it to their most vulnerable students -- beginning with those who have IEPs. If all children with disabilities can attend daily, then schools can begin serving other high-need students, like those in homeless shelters and temporary housing, or those who are learning English.

What will coronavirus testing look like?

Every school will test 20% of its students and staff every week, and everyone returning to the building must consent to be tested. That’s a change from earlier this year, when students were allowed to continue attending even if they had not turned in consent forms. Doing that many tests is a big logistical challenge, and it’s part of why schools are reopening in phases. The city just doesn’t have the capacity to conduct this much testing at every school in the city right now.

What about that 3% trigger for closing schools?

Schools closed last month when the seven-day-average of coronavirus tests coming back positive hit 3%. But that threshold will no longer be used to close schools, and it won’t be replaced with a new one.

There won’t be any metric used to shut schools down citywide. Instead, the city will rely on its more frequent school testing to determine whether the virus is spreading in schools.

While there’s no mechanism for closing all schools, there is a mechanism for closing individual schools. That will happen if the city’s “situation room” determines there are two or more cases within an individual school. A school will shut down for at least the time of a test and trace investigation if that happens. If the investigation determines the virus may be spreading within the school, the entire school will shut down for two weeks.

So fat, 239 schools have been forced to close for a two-week period since the start of the year after positive cases were confirmed in their buildings.

What about remote learning?

Despite all this attention on in-person classes, the vast majority of the city’s 1 million students will be learning remotely, and that’s likely to be true for the rest of this school year. The mayor and Schools Chancellor Richard Carranza have been asked how they are improving remote learning often, and there haven’t been many specific answers.

At a recent briefing, Carranza said the city is working to share best practices and get more students the devices they need to get online:

“It's not sexy sounding, it's not big newsworthy, but we're actually taking what teachers are doing and sharing those best practices with other teachers, while at the same time building our device distribution network and getting more devices, while at the same time making sure that we have a trauma-informed approaches, because, you know, all of all of the city has been, you know, impacted by the trauma of the pandemic,” he said.

Still, about 60,000 students are still in need of devices like tablets or laptops, the DOE says, about nine months after remote learning began in March.