STAMFORD — City public school students outpaced others in the state in their improvement rate on a standardized exam aimed to gauge their competency level in reading and math, according to the district’s recent analysis of the test scores.

Stamford school district officials say city public school students had the highest improvement rate in the state on last spring’s Smarter Balanced tests compared to the previous year.

The Smarter Balanced Assessment corresponds with Common Core standards and is taken online by all third- to eighth-graders over a six-week period.

Stamford students in grades four to eight had an average growth rate of nearly 37 percent compared to the state average of nearly 36 percent.

Stamford students had a 44.5 percent average growth rate in math compared to the state average of 41.5 percent and a 36.7 percent growth rate in ELA compared to the state’s 35.9.

Despite the improvements, Stamford students remained below the state average overall in reading and math.

In Stamford, 48 percent of third- to eighth-graders are reading at grade level, while nearly 44 percent are at grade level in math. The statewide average for reading at grade level was more than 54 percent and nearly 46 percent in math.

Stamford Superintendent of Schools Earl Kim said the inconsistencies could be attributed to the design of the test.

“If there were a difference in growth rates across two types of curricula, that would suggest a problem with the curricula,” he said. “It’s an art more than a science.”

Judith Singer, executive director of research and assessment for Stamford Public Schools, said district officials plan to investigate what caused the inconsistencies.

Singer highlighted the improvement Stamford fourth-graders made in math. She attributed the growth to the elementary program, Everyday Math, that corresponds with Common Core standards. An updated version was introduced during the 2016-17 school year.

Singer said Stamford’s test scores are also affected by the city’s demographics that include a high population of English language learners and special needs students.

“Because the population is different in ways that are very closely related to achievement, it’s not surprising to see them somewhat below state numbers,” Singer said.

However, Stamford’s high needs students had a growth rate similar to the state average.

“Everybody’s improving,” Singer said. “The pattern holds.”

tclark@hearstmediact.com; 203-964-2265; @travclark2