When New York City’s education department announced plans to close a handful of struggling schools in Mayor Bill de Blasio’s turnaround program, they argued the schools were simply too low-performing to stay open.

But while officials were making that argument, students were still being sent to them. In total, 25 students were allowed to enroll across at least some of the six closing Renewal schools after January 1. The full closure plans became public January 6.

Those who enroll after the traditional admissions process is over — referred to as “over-the-counter” students — are often among the hardest students to serve. Many are behind academically, are recent immigrants, have experienced homelessness, or were previously incarcerated.

The city’s decision to allow late-arriving students to enroll in schools they planned to close likely does them a disservice, multiple experts said.

“If they’re going to take the drastic and final step of closing a school, it means that they’ve decided that this school is so limited in what it does for kids that it shouldn’t stay open anymore,” said Norm Fruchter, an NYU researcher who authored a study about how the city assigns late-arriving students, and is generally supportive of de Blasio’s education policies. “Why send any more kids there?”

Schools Chancellor Carmen Fariña has vowed to reduce the number of mid-year students sent to Renewal schools, and the department previously banned several of the city’s most troubled schools from receiving them.

“The policy makes sense,” Fruchter added. “This seems to violate that.”

Fruchter and others acknowledged that deciding where to place the tens of thousands of students who arrive on the education department’s doorstep in the middle of each school year is a challenge.

At the high school level, which is governed by a complex application process, the most desirable schools often have few slots available mid-year, significantly limiting the options for those who arrive late. His research has shown those students are disproportionately sent to struggling schools, which tend to have more open seats.

In the context of the city’s Renewal program, late arrivals pose a difficult catch-22. Many of the schools in the turnaround program are struggling to attract new students, which would bring additional funding. But those schools are perhaps least able to handle an influx of students who are likely to need additional help.

It isn’t a new problem. The Bloomberg administration also struggled to find seats for students who arrived mid-year, and disproportionately placed them in schools that were later closed, or were already undergoing that process.

Deidre Walker has seen that tension play out at her own school. A math teacher at J.H.S. 145 in the Bronx, one of the schools that will be closed next year and received new students, Walker said latecomers are often still learning English or require services like occupational therapy. The school, she said, isn’t always able to meet their needs.

“If you continue to send more and more students that need more and more services in a situation where people are struggling, you need to send more bodies that can deal with the demand,” she said, noting that her school only has one English as a Second Language teacher. “That’s not happening.”

Concern that the school did not receive sufficient resources despite being in the city’s Renewal program was a constant refrain during its contentious closure process.

Michael Aciman, an education department spokesman, said in a statement that mid-year placements are “determined on a case-by-case basis to meet the needs of individual students and families. All students attending a Renewal school slated for closure will have a seat at a higher performing school next year.”

Officials noted that the closure plans for five of the six schools were not officially approved until March, so “these schools were subject to the same enrollment guidelines as other Renewal schools.”

Members of multiple schools that will be closed next year expressed surprise that the city would continue to send students to the schools it planned to dismantle. A teacher at Monroe Academy for Visual Arts and Design, a Bronx high school which has received 11 students since January 1, said she didn’t understand the city’s rationale for sending them more students.

And a senior leader at a community organization that partners with one of the soon-to-be-closed schools, said “it’s hard to imagine a justifiable reason” for the decision. “Those students will inevitably need to start anew again in just six months’ time.”

Other observers were more circumspect. Aaron Pallas, a professor at Teachers College, said that given the thousands of students who are assigned mid-year, sending 25 to closing schools did not seem like a large number.

It is possible that there were logistical reasons for sending them. Some may have been previously enrolled in those schools, for instance, the situation of at least one student who enrolled at J.H.S. 145 in the middle of this year. For others, it could have been the closest school or one that enabled them to stay with a sibling.

“Over-the-counter students are sometimes hard to place,” he said, adding: “It’s hard to know in this case what the logic was.”