PHILADELPHIA – Who should be held responsible for the academic problems in the Philadelphia school district?

Many people would blame the thousands of classroom teachers, who are on the front lines of student instruction. They make, on average, somewhere around $65,000 per year.

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But what about their bosses – the principals and assistant principals – who are ultimately responsible for supervising the teachers and making sure children learn?

The buck stops with them, in more ways than one.

In the 2013-14 school year, a lot of those principals and vice principals made a heck of a lot of money, even though a huge percentage of students continued to struggle academically.

A total of 225 building principals made at least $100,000 in straight salary in 2013-14. The top salary on that chart was $149,890 while the lowest was $108,950.

Sixty of those principals made at least $140,000, 106 made at least $130,000 and 50 more made at least $120,000.

All added up, those 225 principals were paid $30.1 million.

Meanwhile, 45 assistant or vice principals were paid between $104,342 and $129,311. They made a total of $5.6 million.

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The principals and assistant/vice principals made up the bulk of what was clearly a top-heavy payroll in the Philly district in 2013-14.

A total of 331 employees – none of them teachers or other employees stationed in classrooms – made at least $100,000 in straight salary. They pulled in a grand total of $42.9 million.

The top salary went to Superintendent William Hite at $270,000. But the principals were well represented at the top of the scale.

Thirteen of the top 20 salaries in the district went to principals. Two of them ranked sixth and seventh on the list, respectively, with each making $149,890. They were paid more than two assistant superintendents, who were each paid $145,700.

All of that spending on huge administrative salaries – particularly principals – came at a time when the Philly district could barely afford any big salaries at all.

In June 2013, the district announced it was laying off 3,783 employees, including 676 teachers and 283 counselors, to help erase part of a mammoth $304 million deficit.

“Among the targeted teachers are those that teach reading, math, English, special education and music,” the Washington Post reported.

And what did the Philadelphia district get in exchange for the big money paid to all those school administrators? More bad academic news.

In November 2014, Pennsylvania state education officials released their School Performance Profiles.

Individual schools were scored on a scale of 1-100, based on student test scores, graduation rates and student attendance.

A score of at least 70 was considered acceptable.

Statewide, nearly 75 percent of schools scored at least a 70, according to TheNotebook.org. In Philadelphia, only 34 of 214 schools – mostly run by those high-paid principals – were able to make the grade.

Meanwhile, the Philly district was one of 21 across the nation that participated in a special Trial Urban District Assessment in 2015, based on results from the National Assessment of Education Progress test.

Among those districts, 32 percent of fourth-graders and 26 percent of eighth-graders scored proficient on the test, which focused on math and reading.

In Philadelphia, only 15 percent of fourth-graders and 20 percent of eighth-graders made the cut, according to NationsReportCard.gov.

“The trend toward administrative bloat has been going on for decades in American schools,” Ben Scafidi, senior fellow at the Friedman Foundation for Educational Choice, told Watchdog.org.

“We’re spending more and more money on personnel outside the classroom and haven’t seemed to get any returns in student achievement. It’s time to try something else.”

The people in charge of the Philadelphia school district might be wise to heed that advice.

Alissa Mack contributed to this report.