The scourge of student homelessness in New York City, already at record levels, is increasingly falling on the smallest shoulders.

As of the 2016-17 school year, nearly one in 10 elementary-age students were doubling up in the homes of family or friends, living in shelters, or arranging other temporary housing, including in parks, tents, or cars, according to a report released Thursday by the Research Alliance for New York City Schools, a New York University-based group that studies the city’s public schools.

“The problem is most prevalent among our youngest students,” the authors write, noting that the impact can have a significant negative impact on children who experience homelessness at such “a developmentally crucial age.”

By contrast, 7.3 percent of students in middle school and high school were experiencing the same housing instability, although the percentage of students in both categories appears to be growing. (Some of that rise, however, could be attributed to better data collection, the study notes.)

The report also found that 95 percent of students who live in shelters — especially the nearly 19 percent of the homeless who have resided there for three or more years — were black or Hispanic. The figure underscores “the disproportionate impact of extreme poverty on NYC’s Black and Latino students,” the authors write.

Researchers don’t have a definitive answer as to why younger students are experiencing homelessness at a rate higher than their older peers. One guess, according to Zitsi Mirakhur, a research associate and one of the authors of the report, is that families may only enter a shelter with younger children, while sending older children, who are relatively more independent, to stay with relatives.

What they did try to study was what educators and the school system more broadly could do to improve academic performance in schools with high levels of homelessness, where “students arrive at their schools with heavy academic, social, and emotional burdens.”

Researchers specifically looked at five schools with more students living in shelters than the citywide average, but where students were performing academically on average with students who live in permanent housing citywide. They wanted to see what schools were doing right in serving their students, Mirakhur said.

The answer, she said, is that many staffers take matters into their own hands. The report cites educators consoling families, joining them on visits to the city’s homeless PATH intake center, and coordinating with families to pick up students so they can make it in time for free breakfast. But the staggering number of students in need “makes it almost impossible,” the authors write.

“A lot of schools’ staff talked about how they end up in these triage situations,” Mirakhur said. Researchers talked to 18 staffers. “Students have immediate needs — they need food today, they need a coat, they need school supplies,” she recalled them telling her.

Some of the most helpful strategies that staffers cited were having non-instructional staff who focused on homeless students and partnerships with community-based organizations, although such arrangements, tenuous and “ad hoc,” were also vulnerable to disruptions and discontinuity.

By looking at attendance data, a Harlem principal discovered that a chunk of her homeless students were leaving midday because they had to join parents for mandatory appointments with social service agencies. That sort of information allows the school to “step in and say to the agency, ‘You need to reschedule. They’re missing two hours of instruction every Tuesday,’” the principal told researchers.

About 10 percent of the homeless students studied in the report started school in District 10 in the Bronx, which includes the Riverdale, Bedford, Fordham, Belmont, and Kingsbridge neighborhoods. Mirakhur said they don’t know why a district with pockets of relative affluence would also have the highest levels of youthful homelessness but speculated that a number of schools they focused on were near clusters of homeless shelters.

Miranda Barbot, a spokeswoman for the city education department, acknowledged there is “more work to be done,” but pointed to city investments, such as yellow bus service for students in shelters, which the study mentions as a positive step. The department also expects to spend $12 million on hiring 100 coordinators by the spring to work at schools with high populations of homeless students, more training for educators on how to offer supports, and managers who will take on a regional role in overseeing homeless services.

The department currently spends $16 million on a few other efforts: a special social worker program, enrichment programs at shelters, and placing students in shelters closer to their schools.