J.C. Nalle Elementary School was at risk of closure in 2011 because of low academic performance and flagging enrollment. Two years later, the school had the biggest math test score gains in D.C. Public Schools, with a 27 percent increase in proficiency rates.

A report released Wednesday by Child Trends, a Bethesda-based research center, found the improvement to be a result of a series of interventions that could be replicated in other schools.

“If you look at the research, there are plenty of school turnaround efforts that don’t work,” said Daniel Princiotta, principal research scientist for the study. He said the advance in math scores at J.C. Nalle was rapid and substantial.

The positive results were not mirrored in reading. J.C. Nalle students’ performance in reading has remained lower than that of similar students at other schools, the report said.

But the study found that several of the Southeast Washington school’s interventions in math were effective, including increasing the use of technology, extending the school day and holding school on Saturday. The report noted specific successes that contributed to the turnaround:

●New investments in tablets and laptops as well as math-related software, specifically ST Math and First in Math, helped personalize lessons and gave students a way to continue working on their skills outside of class.

●The school used a $275,000 grant from D.C. Public Schools to add about 75 minutes to the school day for students in grades three to five, allowing for more academic instruction and one-on-one teaching.

●A family-oriented program was offered on Saturdays, including academic interventions and parent workshops.

●A $6.8 million renovation of the school during the summer of 2012, along with many years of sustained support from community partners.

“All of these interventions built on earlier, longer-term investments by the school and community partners that addressed both academic and nonacademic barriers to learning,” said Zakia Redd, a senior research scientist at Child Trends and the lead author of the study. “The staff and families of J.C. Nalle were primed to take advantage of this kind of investment.”

J.C. Nalle, which opened in 1950, became the city’s first community school in the late 1990s. It was redesigned on the principle that to help vulnerable children achieve academically, a school must also meet their needs outside of school.

Community schools partner with outside organizations to provide supports such as health care, enrichment, mental-health services and counseling for the whole family. The D.C. Council voted to expand the model to five more schools in 2013 and advocates are hoping to expand it further.

For more than a decade, J.C. Nalle has partnered with the Freddie Mac Foundation and the National Center for Children and Families.

Sheryl Brissett Chapman, executive director of the National Center for Children and Families, said it provides about $800,000 to $1 million annually in staffing and resources to the school. In addition to services such as dental care and counseling, she said, the school has provided specialized programs for grandparents and fathers who are reentering their children’s lives after incarceration. It has offered employment and financial literacy training for parents and after-school activities and tutoring for children.

The Freddie Mac Foundation, the biggest funder, dissolved this year. Chapman said the program has two more years of funding for the community school, but will need to find a new philanthropic partner. The foundation also funded the study of the school’s turnaround efforts. The community school partners helped fund the technology initiatives and Saturday school interventions detailed in the report.

The impact on math performance was substantial and lasting, according to the study, which looked at performance from 2010 to 2014. Students’ average annual math improvement was the equivalent of almost five months more than that of students from other D.C. schools with similar demographics.

Students’ reading performance did not improve at the same time. In 2014, 52 percent of J.C. Nalle students performed at a proficient level or higher in math and 30 percent performed at proficient or higher in reading.

Some gains in reading proficiency rates in 2013 were offset by an increase in the number of students performing below basic levels.

The report cited some possible reasons for poor results in reading, including later implementation of reading software and the fact that the study focused on third- through fifth-graders, who take the city’s standardized tests, while younger children might have been more likely to benefit from reading interventions.