He got schooled.

Mayor Zohran Mamdani defended his decision Tuesday to reopen public schools as parents, students and teachers faced a treacherous return a day after a monster storm dumped 2 feet of snow on the city.

Facing a blizzard of criticism, a reeling Mamdani argued that the city Department of Education wasn’t yet ready to switch to remote learning and that schools were “critical to the health and wellness” of students.

But all told, just 63% of students returned to school Tuesday, said schools Chancellor Kamar Samuels, well below the average attendance rate of 88-92%, according to the city’s Independent Budget Office.

Roughly 12,000 teachers called off, forcing the city to tap 5,000 substitutes, Mamdani said. The city has 78,300 teachers, meaning 15% were out.

“With students coming back from mid-winter break, it was not possible to ensure that enough students had the devices they needed to effectively participate in remote learning,” Mamdani said during a news conference updating New Yorkers on the storm response.

“Our public schools hold a purpose beyond providing a designated place for kids to learn,” he said. “They are critical to the health and wellness of nearly 900,000 children across our city. Whether it’s a warm meal, essential mental health support or a source of childcare for working parents, in-person schooling is a resource that our city’s children — and families – depend on.”

The return-to-school was especially galling for many New Yorkers after Mamdani gave the city’s students a traditional snow day on Monday following the historic blizzard – and as snow cleanup remained uneven across the boroughs and commuter chaos continued.

Some schools – especially on Staten Island, where 29 inches of snow fell on its east shore – were virtual ghost towns. 

One Staten Island high school had 180 staff members out, while multiple other schools reported 15% to 20% student attendance, Councilman Frank Morano (R-Staten Island) said.

“What is the possible educational value of opening schools today?” Morano fumed. 

“One principal told me that if they had remote education they would have had 96% attendance. I hope that we can take a look at local autonomy and allow a little bit of flexibility for school districts that don’t have a subway and are car dependent.”

Many students in the Forgotten Borough had to walk in the streets to get to class.

Sanitation honchos said they were shifting resources to Staten Island to clear snow.

“This is small, difficult work, and some of these hilly and narrow streets will take hours to clear,” said Javier Logan, the sanitation department’s acting commissioner. “It is a snow falling operation that I’ve never seen in my 27-year career.”

The troubles getting around Staten Island – which were compounded by bus detours, the Staten Island Railway only partially running and power outages – made it the decision to reopen schools ridiculous, said City Council Minority Leader David Carr.

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“Today should have been another snow day or a remote learning day,” Carr (R-Staten Island) told The Post.

“Everyone is having a hard time, but there are many teachers who can’t make it in today as well as students. Parking is practically nonexistent for faculty and staff because the plowing inevitably covers curbside spots on our roads.”

Around 75% of city schools had fewer than half their students show up for class on Tuesday, city data shows. Two schools — Concord High in Staten Island and Research and Service High in Brooklyn — had less than 15% attendance. 

The simmering frustration and outrage was a polar opposite when Mamdani’s decision to close schools Monday drew a collective breath of relief from students, parents and teachers as Winter Storm Hernando bombarded the city with blizzard conditions.

He announced the traditional snow day in a cutesy video with eighth-grade student Victoria Mompoint, who exclaimed with glee at the news. 

But Mompoint turned on the mayor when he declined to give kids a snow-day sequel. 

“A lot of people are telling me, texting me on Instagram, ‘like, can you call the mayor back?” the 14-year-old told Gothamist.

“It’s not even like kids don’t want to go to school — kids don’t want to wait for a bus that’s going to take probably 30 minutes plus and climb over mountains of snow, and it’s probably not possible that all the snow is going to be cleaned off by the time that kids have to go to school tomorrow morning.”

The teen wasn’t alone.

A Change.org petition to make schools remote Tuesday drew an astronomical 172,000 signatures and even many of Mamdani’s allies were baffled by his decision.

One teacher told The Post he had to take an Uber to work after she slipped and fell on the ice.

“I only live 10 blocks from school, and so I had the best of intentions to get there, and I fell twice, and my knee is all scraped up, and my ankle still hurts, and I’m not old, right?” he said.

“In my opinion, there was no reason not to be remote today if you trust your teachers and students and believe in them to do the right thing.”

Democratic Councilwoman Kayla Santosuosso said there was no way her district – which covers southern Brooklyn – could safely make it back to school after the intense snow.

“I had some teachers say that they had more absences in their school than subs who showed,” she said. “My district is still a mess all over despite DSNY moving mountains.”

Wintry woes extended further north in Brooklyn, where outspoken lefty Councilwoman Shahana Hanif – a Democrat who represents the crunchy neighborhoods of Park Slope, Gowanus and Cobble Hill, as well as Borough Park and Kensington – blasted snow removal efforts.

She revealed a snowy subway station and school entrance in an X post.

“Okay, schools are open and I know parents are relieved but is/was there a plan to ensure sidewalks and entrances were fully cleared so students can safely walk into the building without slipping?” she posted just after 10 a.m.

Councilwoman Joann Ariola (R-Queens) said her district was plagued with icy issues.

“My office has been inundated all morning with calls and messages from teachers who can’t find parking and staff who couldn’t enter their buildings due to snow buildup,” she said.

“They really should have had a remote day, to give the city time to get things cleared out near our schools. That didn’t happen, and now we have this mess today, confirming all of the things we all knew were going to take place.”

Fears over safety forced city workers to clear thousands of unshoveled sidewalks and other areas that were really private property owners’ responsibility, sanitation reps told The Post.

New Yorkers could also have to brace for stumbling around towering mountains of trash as garbage collection won’t return to normal until Monday, officials said.

Council Speaker Julie Menin (D-Manhattan) acknowledged the lawmakers’ and parents’ concerns about schools.

“I think moving forward – while it’s always difficult in these storms as to what the right course of action is – having some kind of flexibility is very, very important for parents in these tough storms,” she said.

The state’s department of education gave a “waiver” for Monday’s snow day – meaning the city won’t be penalized and lose funding if it doesn’t mean the 180-day school day requirement, according to the United Federation of Teachers union.

The waiver only covered Monday and stemmed from Gov. Kathy Hochul’s state of emergency declaration issued before the storm, education officials said.

Schools could apply for waivers covering additional days, according to state guidance.

– Additional reporting by Hannah Fierick, Haley Brown and Carl Campanile