The percentage of New York students passing the state algebra exam rebounded this year after worrisome results the previous year raised concerns that graduation rates could take a hit.

Seventy-two percent of students passed Algebra I in 2015-16, according to data released by the State Education Department on Monday, nine percentage points higher than the share of students who passed the exam in 2014-15. Students are required to pass an algebra exam to graduate.

When state officials announced plans to switch to a more difficult Common Core algebra exam, officials said they would attempt to maintain similar passing rates to avoid a drop-off in graduation rates. But in 2014-15 — the first year in which the majority of students took the new exam — only 63 percent passed it, nine points lower than the percentage who passed the former “Integrated Algebra” test in 2013-14. That drop caused widespread concern the state had miscalculated and many students would be held back from graduation.

But Monday’s results are proof the slow phase-in of the Common Core exams is working, said Jhone Ebert, senior deputy commissioner for education policy.

“We’re very excited about the passing rates. It shows the hard work that the teachers have been [putting in] in their classrooms,” Ebert said. “They have higher expectations for their students.”

This year, more students passed the Algebra I exam statewide and in New York City, which saw a 10 percentage point increase, pushing the city’s passing rate to 62 percent.

It is unclear why the scores increased so dramatically, though Ebert said the bulk of the score increase is attributable to teachers and students getting accustomed to the more difficult exams.

The state also conducted “scale maintenance” last June, designed, in part, to keep the passing percentages roughly equal to what they were before the Common Core, which Ebert said could have played a small role in the increase. The score changes meant students had to answer roughly two fewer questions correctly in order to pass the June exam, but state officials said that could also indicate a harder test.

The algebra exam is symbolic of the tricky dance state education officials are trying to perform, as they work to give students more ways to earn a diploma while also maintaining the rigor of a New York state diploma. The algebra exam has long been a graduation roadblock for students in New York state. Many students end up taking — and failing — the exam several times, a phenomenon that has been dubbed the “algebra whirlpool.”

Education consultant David Rubel pointed out that there are still many students who failed the test and could still struggle to graduate.

“Were they kids who almost passed and will the next time they take it? Or are they kids who are really struggling?” Rubel asked. “That, to me, is the real question.”

Recognizing the hurdle algebra presents, New York City instituted an “Algebra for All” initiative, which seeks to strengthen math supports in earlier grades, push more students to take algebra in middle school, and help all students be better prepared to take algebra by the time they reach high school.

On Monday, the city’s Department of Education officials celebrated the increase in scores.

“We’re pleased to see more of our students passing the Algebra I exam, and we’re investing in continued progress for all students through the Algebra for All initiative,” said education department spokesman Will Mantell. “By 2022, all students will have access to an algebra course in eighth grade and complete algebra no later than ninth grade.”