At a protest on Monday in Brooklyn, teachers highlighted their concern over the fact that a handful of schools in the city that still lack proper ventilation.
The United Federation of Teachers (UFT) also claims that 2,000 additional teachers being brought in by the city to cover the new mix of in-person and virtual learning are not enough.
And teachers are concerned about COVID testing. On Monday, Mayor Bill de Blasio announced that 55 school employees have tested positive for the virus.
RELATED: 55 positive COVID-19 cases among NYC school employees
That is a positive testing rate of just .32%, but teachers say one school in Brooklyn with a positive case was not immediately disinfected -- and it took the district three days to notify people.
The mayor acknowledged there will be some bumps in the road.
"We will see some people unfortunately test positive," he said. "And they'll be out, you know, for about two weeks and then come back. We will see some classrooms shut down, of course. And as for whole schools, it's too soon to tell. You could see that."
One of the buildings in question is the Martin Luther King, Jr. education complex on Manhattan's Upper West Side.
RELATED: City Council members push to delay in-person learning
It has classrooms on the interior with no outside windows, which de Blasio said is the only school building he knows of that will require an alternative site following the ventilation inspections.
Teachers and staff have also expressed concerns over added travel time depending on where the students end up, possibly at the campus of Manhattan Community College, when they would prefer to stick with remote learning.
RELATED: New York, New Jersey, Connecticut out-of-state travelers quarantine list
MORE CORONAVIRUS COVID-19 COVERAGE
Back to school information
How coronavirus changed the New York region
Do you have coronavirus symptoms?
What's Open, What's Closed in the Tri-State area
COVID-19 Help, Information. Stimulus and Business Updates
New York City
Westchester and Hudson Valley
abc7NY Phase Tracker: