The mask requirement is among the health and safety changes implemented for the school year after the district's board of trustees voted Aug. 12 to approve a mandate.
The mandate requires everyone inside HISD buildings and buses to wear masks, regardless of vaccination status. The district is also encouraging masks to be worn outside.
"This decision stems from one simple fact. If we can save just one life, then it's worth it," said Superintendent Millard House II, who spoke from Parker Elementary on Houston's southwest side.
House visited multiple schools Monday and plans to do the same on Tuesday to kick off his first school year as the district's superintendent.
While at Parker, he called the first day of school a day to "celebrate," given that many students haven't been in the classroom for 18 months.
But he also addressed the district's mask requirement and how it plans to respond when there are COVID cases.
"Let me be clear. Masks are not a choice," House began. "If we run into a situation where individuals don't comply with what that mandate is, staff can be, unfortunately, met with discipline."
"Students, it's a little bit different situation where if they don't comply, we'll be separating them from the rest of the population in their classroom, asking parents to come get them. If they don't comply beyond that, they'll be moved into a temporary virtual status," he continued.
The superintendent explained that seating charts are in place in classrooms and cafeterias to help with contact tracing once there's a positive case.
"We'll have positive cases today. It's just the nature of what we're dealing with in public education right now," House said.
Still, there's no threshold of cases required to close a school. However, he explained, the district may take other actions to mitigate the spread such as closing part of a classroom or grade level, depending on the situation.
HISD's first day of school for the fall semester happened to land on the same day that the FDA gave full approval to Pfizer's COVID-19 vaccine, meaning it now carries the strongest endorsement from the U.S. agency.
And while some cities and other large school districts across the country have decided to mandate vaccines, House said HISD isn't there yet.
Instead, they're offering incentives like a $500 stipend to employees if they can prove they're fully vaccinated as well as COVID relief time that allows workers to take 10 days to step away if they have the illness or need to quarantine.
As for other safety measures, elementary students will get their temperatures checked when they arrive at school because they are too young to be vaccinated.
Currently, only people 12 and older are eligible for the Pfizer vaccine. In order to receive a Moderna or Johnson & Johnson vaccine, you must be 18 and older.
No vaccine has been authorized yet for children under the age of 12.
If HISD's school board approves it, staff may also need to undergo health screenings.
Other protocols include cleaning buildings with hospital-grade disinfectant. Visitors will be limited to only those who are essential and pre-scheduled.
In-person gatherings are allowed, but everyone must be wearing masks and social distancing.
House told ABC13 on Sunday that health changes made in the district are influenced by his position as both a parent and an educator.
"I say this as a father, so those mothers and fathers out there know that your leadership understands where you are. I have that knowledge myself. But I have done everything earthly possible from masking to putting dollars where we need to reaching out to people I know who can help as well," House said.
You can visit the HISD website for more details on the health and safety protocols for the new year.
The district also recently announced that it would offer a virtual learning option for students who are 11 or younger with compromised immune systems.
The program begins on Monday, Aug. 30.
House said though the state won't provide funding for the virtual instruction program, the district plans on leveraging money from the Elementary and Secondary School Emergency Relief Fund to cover the costs.
Parents of eligible students will need to submit an online form and submit medical documentation to their campus by Wednesday, Aug. 25.
HISD is the largest public school district in Texas and the seventh largest in the United States.
You can watch Superintendent Millard House II's remarks from the first day of school in the video below.
For more back to school coverage, follow Charly Edsitty on Facebook, Twitter and Instagram.
For updates on HISD, follow TJ Parker on Facebook, Twitter and Instagram.