State officials uncovered astonishing evidence that city high school diplomas are worthless — a Manhattan classroom of 11th-graders reading “The Three Little Pigs,” The Post has learned.

The report from the state Education Department says the classic children’s fairy tale was just one of several ridiculously easy reading assignments uncovered at Landmark High School this year.

“‘The Three Little Pigs’ story was read round-robin style in a grade 11 classroom, which demonstrated limited student access in this class to grade-level text,” according to the department’s Office of Accountability.

A two-day review of the Chelsea school — which has been flagged for poor performance — found some obviously “low-level” texts in other classes as well.

But some students at Landmark struggled to deal with age-appropriate books.

“In classes where students were observed reading challenging text, when asked to answer simple questions about the text, most either reread the words in the text or said they did not know,” the report says.

“The Three Little Pigs,” a mostly illustrated text, is, in fact, recommended at the city’s public schools — but for pupils who have just finished kindergarten.

A former city education official called the Landmark example “mind-numbing.”

“I can’t even believe this is part of a high school’s instruction,” the ex-official said. “I’m very surprised to see this. This doesn’t seem reasonable for a high school.”

In other findings revealed by the state, kids at Flushing High School — where The Post revealed that 150 failing students took quickie “credit recovery” classes to graduate — couldn’t recall ever getting assignments that were “memorable or challenging.”

At Brooklyn’s Boys and Girls High School, more than one-third of all classes were being disrupted by students’ chatter a month after Mayor Bill de Blasio touted supposed improvements there in March.

The city DOE said the use of “The Three Little Pigs” at Landmark was a five-minute “Do Now” activity at the start of class to get the juniors settled down and ready to work.

It was also intended to help the kids consider whether telling the tale from the wolf’s point of view would change the moral of the story, officials said.

“The purpose was to use a simple, well-known story to support understanding of bias in a college-level text,” Principal Caron Pinkus said in an email. “After this introduction exercise, students held a discussion about bias and point of view in the college-level texts they were reading.”

But Robert Pondiscio, a senior fellow at the Fordham Institute, said, “’The Three Little Pigs’ . . . is simply not a grade-level text, at least no version I’m aware of. Color me skeptical.”

Additional reporting by Michael Gartland