Tracking is pervasive in New York City from kindergarten through high school, with 28 percent of all schools sorting students based on grades, test scores and other factors.

That’s why Chancellor Richard Carranza’s comment that screening is “antithetical” to the mission of public schools was so surprising. But the question is, what can he do to change the system?

Any action will be contentious and difficult. On the one hand, advocates argue that screening creates divisions along racial and socioeconomic lines. However, others say it has produced some of the most popular, even iconic schools in the city and helps keep middle class families in the public school system.

If Carranza is serious about tackling problems with screening, here’s a list of five areas he could tackle.

1.) Eliminate District 2 priority

New York City’s high school admissions process is based on the idea that students can apply to any school in the city, regardless of their zip codes. But one of the wealthiest school districts in the city has essentially cordoned off certain schools for students who live within the district’s boundaries

District 2, which encompasses the Upper East Side and downtown Manhattan, is home to some of the most popular high schools in the city, including Eleanor Roosevelt and Baruch College Campus High School and N.Y.C. Lab School for Collaborative Studies.

These schools have near-perfect graduation rates, and thousands of students rank them as one of their top 12 schools each year. However, they are so competitive it is nearly impossible for students outside of the district to snag a seat.

Maurice Frumkin, a former city education department official who now runs an admissions consultancy, said it’s heartbreaking to tell students that the rules effectively prevent them from attending a great school.

“I have to sit with kids in the Bronx who are more than qualified for Eleanor Roosevelt and I have to tell them, ‘Sorry, you can’t get into that school. It’s impossible,’” Frumkin said.

These schools enroll a disproportionately low share of black and Hispanic students. For instance, 15.5 percent of Eleanor Roosevelt’s student body is comprised of black and Hispanic students. Citywide, about 67 percent of students are black and Hispanic.

2.) Change the admissions rules at five specialized high schools

At the red-hot center of this fight are eight elite high schools that admit students based on a single test. These schools have drawn intense scrutiny after only about 10 percent of admissions offers went to black and Hispanic students this year.

The city’s official position has long been that admissions at specialized high schools are codified in state law. But in fact, only three schools — Stuyvesant High School, Bronx High School of Science, and Brooklyn Technical High School are written into state law. Experts say the city could change admissions at the remaining five schools with a vote from the city’s school oversight board.

Mayor Bill de Blasio recently said he will “revisit” the subject. Carranza has also seemed receptive to changes, saying that he is not in favor of single-test admissions.

Without a single test, the city could pick new admissions methods that would likely lead to a more diverse student body. They could select the top-performing students at middle schools across the city, or admit students based on factors such as grades and attendance.

3.) Create one common application for all screened schools

Since New York City’s screened schools have latitude to craft their own admissions criteria, students may have to submit test scores, grades, examples of their work, and attendance records. Or they may have to sit for tests at the schools, interviews, write essays, or complete artistic auditions.

The set of requirements is dizzying and disadvantages students without the time and savvy to  navigate the system. Those learning English might find it difficult to navigate school websites. The High School Directory, a large book of school options intended to help students sort through admissions requirements, has historically left out information. Some of the open houses that explain this information are nearly impossible to get into and affluent families can pay for a service that tells them when to be near a computer to sign up.

Additionally, fulfilling some of these requirements is easier for families preparing years in advance. For instance, one of the city’s most prestigious schools, Beacon High School, asks students to submit a sample of their work. However, that is only possible if students know in advance to save their best work. Many parents from more affluent areas of the city start preparing for high school admissions early — sometimes in elementary school.

If the city instituted one, centralized set of admissions requirements for screened schools, the process would be simpler to navigate. That may help students from low-income backgrounds who have difficulty sorting through the process now.

City officials are aware that applying to high school can be difficult for families. Officials have tried to tackle the problem by providing more information to students and parents. For instance, they launched a tool that helps students search information about schools and provide more translated copies of the High School Directory. They also promised to improve access to open houses.

4.) Reduce the share of screened schools throughout the system

Advocates who believe any screening mechanisms, including test scores, attendance rates, or auditions, are inherently biased, say the city should either eliminate screening or seriously reduce the share of schools allowed to pick their students.

Nearly a third of high schools in New York City today have some screen for academic success or artistic talent — but it wasn’t always that way. During Mayor Michael Bloomberg’s administration, the share of screened schools shot up around the city. In 2002, only 15.8 percent of school programs screened students for academic success. By 2009, that share had increased to 28.4 percent. (Some schools have multiple programs.)

Further sorting takes place far before high school. When students are as young as four they can sit for a Gifted & Talented test. These G&T programs are starkly segregated by race and class. Additionally, students are screened in one quarter of middle schools.

Matt Gonzales, who supports school integration work through the nonprofit New York Appleseed, said he believes middle schools screens should be eliminated. “Especially for 9 and 10-year olds, it’s kind of ridiculous to put kids through this process,” Gonzales said. “We’re actually just screening for families and not kids.”

City officials said they are trying to eliminate the use of screens when possible, but so far have not set a target for reducing the share of screened schools in the city.

5.) Require that screened schools set aside seats for students from disadvantaged backgrounds

Some of the city’s Gifted & Talented programs and Bard High School in Queens are already prioritizing admissions for some students who qualify for free-or-reduced-price lunch, which is often used as a proxy for poverty. The city could expand the number of schools doing the same.

Gonzales said it would make sense to start with a set aside program. Ultimately, he would want to see some type of “controlled choice” formula that takes a student’s background into account when assigning a school. (In this scenario, the formula could include both academic success and socioeconomic status.) But in the meantime, it might make sense to start smaller, he said.

“Whatever we do is going to have to be iterative,” Gonzales said. “Starting off with some priority system or set aside system, I think that would actually be a very good, methodical way to start tinkering with the way we do admissions.”