Newark officials have postponed a new high-stakes test that will be given to students hoping to attend the city’s most sought-after high schools.

Eighth-graders were originally supposed to take the brand-new exam this Friday or Saturday. But the district quietly changed the test dates to Feb. 15 and 16 on its enrollment website, without providing an explanation.

A district spokeswoman on Tuesday attributed the change to “logistical modifications.” School staffers said they first heard about the scheduling change last week.

The delay adds to uncertainty surrounding admissions to six “magnet” schools that are the district’s top-performing high schools.

In recent years, each magnet school has set its own admissions criteria, which have included students’ grades, state test scores, attendance records, interviews, and auditions. But last month, with the enrollment process for next school year already underway, the district’s new superintendent announced that every aspiring magnet student would have to sit for a new test in January.

Officials said the test would assess applicants’ reading and math skills as well as their interest in the schools’ themes. But they have not shared other important information, such as how much weight the test results will be given relative to the other admissions criteria that schools will continue using.

Even as families try to figure out how the test will affect their children’s chances of getting into one of the coveted magnet schools, officials were still tweaking the exam as recently as last month.

“Right now, we are in the process of finalizing the test,” said Superintendent Roger León at the December school board meeting, adding that he planned to add “a couple of questions.”

“I’m looking forward to providing a really good quality [exam],” he said, “that will be worth our students’ time.”

The district spokeswoman did not respond to detailed questions Tuesday about how the test was created or what will be on it.

Karen Gaylord, who works with parents at Science Park High School, said she believes the later test date will allow families to focus on applying to schools without worrying about the new test.

Families have until Feb. 15 to submit applications — the same date when Newark Public Schools students will now take the magnet-school test. (Students in non-district schools, such as private or charter schools, will take the test the following morning.)

But Gaylord said she is still waiting for information from the district about how the new test will be used. For example, she was not sure whether each magnet school will decide whether to give more weight to students’ grades or their exam scores, or whether the district will set the rules.

“These are still questions marks for me,” she said.