Mayor Bill de Blasio’s rise to power was supposed to ease the pressure on principals to post statistical gains. De Blasio quickly eliminated rankings and letter grades from the city’s school evaluations and declared he would not close low-performing schools.

But that has not stopped some high schools from pushing students toward graduation in illicit ways, according to a recent spate of city investigations and reporting by the New York Post. The details include schools that have changed grades of students who failed a course and some that have given credits without any teaching.

The Post has responded by calling for de Blasio to fire Chancellor Carmen Fariña, though similar academic wrongdoing long preceded the current regime. The city’s response has been a pledge to proactively sniff out academic fraud, an approach not taken up by the Bloomberg administration.

[Read more about the city’s new task force here.]

Behind the tug-of-war is a complicated set of problems for New York City schools. Low-performing high schools, now under threat of being taken over by outside groups, are still under pressure to increase their four-year graduation rates. With many students still entering ninth grade well below grade level, schools have long relied on “credit recovery” programs, many of which operate within city guidelines, to keep students on track.

Here’s a guide to credit recovery and how it came to dominate the news cycle once again.

What is credit recovery, anyway?

When a student fails a course in high school, he or she doesn’t necessarily have to wait until the next semester to retake it. At many schools, students can earn credits through condensed makeup courses that target specific topics.

The practice is broadly known as “credit recovery,” but it can look different from one school to the next.

"Some schools are trying to make things make sense for students. Some are trying to cheat students."Leslie Santee Siskin

Some see the work as a way to help troubled students who have the skills to stay on track. Tech-savvy principals have embraced the courses as a way to award credits who through classes conducted partly online. Students at transfer high schools, which serve older students who have left traditional schools, say they provide much-needed flexibility.

But critics say the programs too often serve students who are simply unmotivated, undermining the value of an academic credit.

In 2012, a social studies teacher from a Queens high school recalled how his principal ordered him to enroll any student who failed his class in a credit recovery program. The students were corralled into a library and told to complete a packet of 75 multiple-choice questions and two essays.

“Some students completed the packet, others did not,” the teacher wrote. “All got credit.”

How many students earn credit that way?

It’s hard to tell. Only since the 2012-13 school year has the Department of Education actually tracked credit recovery courses using specific codes. A department spokesman said Tuesday that he could not say how many credits were earned through credit recovery citywide, or at individual schools, for any year since.

The newest data we do have shows that only a small number of students earned credits through credit recovery. In 2010-11 and 2011-12, 1.7 percent of total high school credits were earned that way.

Many of the schools that relied more heavily on credit recovery were transfer schools or were phasing out, with large shares of high-needs students. At Pacific High School, nearly one in three credits earned in 2012, its final year, came through make-up courses.

Why is this getting so much attention now?

Recent investigations and high-profile news reports have focused new attention on how some schools are inflating graduation rates by changing grades or enrolling students in credit-recovery programs that fall far short of the state’s requirements.

"I think it's cynical and has nothing to do with subject mastery and retention."David Bloomfield

A report by the education department’s investigative arm last month found programs where students received no instruction at John Dewey High School. Meanwhile, the New York Post has chronicled how students looked up answers to questions online (at Flushing) and earned science credits for studying math (at Lafayette). In past years, Chalkbeat has reported on instances when teachers were pressured to give credits to students who failed their courses (A. Philip Randolph) and creative ways that students made up physical education credits (Pace).

On Sunday, the Post published a front-page account of an 18-year-old who barely attended government class at William Cullen Bryant High School, and still passed.

Few educators would say those stories portray valuable educational experiences. The credit-recovery programs in particular look like a loopholes designed to help students cheat the system and to help adults avoid the consequences of a school’s low graduation rates.

“I think it’s cynical and has nothing to do with subject mastery and retention, and everything to do with kicking the numbers up,” said David Bloomfield, a professor of educational leadership at the CUNY Grad Center and Brooklyn College.

The city has investigated specific complaints about such programs in the past. But until now, officials had not set up a systematic way to look at how credit recovery was being used.

Is there anything good about the programs?

Plenty, some educators say. Credit recovery, when properly planned and supervised, is sanctioned by the city and helps many students reach graduation who might have otherwise fallen behind or dropped out.

In 2012, special education teacher Sam McElroy wrote on Chalkbeat that he had heard about credit-recovery scandals, but was won over after a year leading a blended learning initiative at Flushing High School.

“The scheduling flexibility it allows, the quality of the content that can be delivered, the ability to individualize courses,” he wrote, are “undeniable benefits.”

Leslie Santee Siskin, a research professor at NYU Steinhardt who studies high schools, explained that the outlier programs get most of the attention — and the outliers are pretty bad.

“There are probably lots of other students who can work on their own with a computer program and show that they’ve filled the gaps,” she said.

“Some schools are trying to make things make sense for students,” she added. “Some are trying to cheat students. It’s important to tease out which is which.”

The Post wants Chancellor Carmen Fariña to resign. How did we get here?

As we wrote in 2011, credit recovery is “an old practice with a new name.”

It rose to prominence under the Bloomberg administration, as high schools faced more pressure to graduate students within four years — a priority that trickled down from No Child Left Behind, the federal law whose provisions designed to hold schools accountable for their success considered only four-year graduation rates in its early years. Credit recovery made increasing sense for struggling students who would otherwise spend semesters re-taking courses.

"I wonder if they would have been better off spending the extra year in high school, really learning something, and then going on to college. "City high school teacher

Teachers have been conflicted about the programs for years. In 2009, Chalkbeat wrote about one teacher’s “second thoughts” about using credit recovery to get a group of her struggling students across the finish line of graduation.

“I wonder if they would have been better off spending the extra year in high school, really learning something, and then going on to college,” the teacher wrote.

As new research showed that a steady accumulation of credits was a key predictor of a student’s eventual graduation, the city began to track how many credits a school’s students earned each year. In 2007, those numbers began to factor into school assessments, which were in turn used to decide what schools the city would close.

With the Bloomberg administration’s school-accountability strategies in full swing, informal credit recovery programs came under scrutiny. Prior to 2009, state regulations didn’t actually allow for students to earn course credit without a certain amount of “seat time.” That changed by the 2011-12 school year in an effort to bring oversight to the programs, though the policy was being examined again by 2012, when a state official said he had grown concerned that the policy was being used in ways outside its original intent.

The city itself restricted credit recovery in 2012, limiting how many courses a student could make up. Meanwhile, stories about programs that skirted the rules popped up again and again.

Michael Dowd, a social studies teacher at Midwood High School, said schools under Fariña feel less frenzied to show gains, reducing the worries that can fuel grade inflation and inappropriate credit-recovery schemes. The city has removed two of the big sources of pressure, he said: “The closure threat — coming from the city, anyway — and the progress reports, which reward you for credit accumulation.”

Still, for schools trying to strike the right balance while avoiding state sanctions, Bloomfield said it is often a “no-win situation.”

“You either adhere to high standards and kids will fail and they won’t graduate and it will be held against you,” he said, “or you let kids coast and you’re splattered over the front page of the New York Post.”