A private school for upper-income families in NYC has been quietly segregating students in their classrooms.

The first sentence of LREI’s mission statement defines the school as a “progressive” place of learning: We pride ourselves on being a progressive pre-K through twelfth grade school.

Segregation by race…how very progressive…

Remember when the Democrat Party lost their fight to keep schools segregated by race after the Republican majority passed the Civil Rights Act of 1964? Well, it looks like they’re at it again…

According to the New York Post, parents are irate over a plan to segregate students by race at the celebrity-friendly Little Red School House in the West Village.

In the last month, parents at the $45,485-per-year private school, which counts David Schwimmer, Christy Turlington Burns and Sofia Coppola’s offspring among its pupils — became aware that Director Philip Kassen would place minority middle-school students in the same homerooms come fall.

They also learned that the race-based placement policy had already been in effect for the 2017-18 school year for 7th and 8th graders, and would likely be expanded to the 6th grade in September.

Each grade, which has approximately 40 students, has two homerooms. Students remain with their homeroom groups for 30 percent of the school day.

Parents revolted at the revelation.

“My daughter who is 11 was like, ‘Wow, this is crazy. They are talking about separating by color,’” one father, who asked to remain anonymous, told The Post.

“And I was thinking how antiquated is this? This is backwards. It’s almost like segregation now.”

After a Post inquiry, Kassen sent a message to parents Wednesday detailing last year’s race-placement “initiative” — which multiple sources said they had never been informed of.

But parents said the school has always let race play a heavy hand in class placement. One mother said for three years all but one of the 10 non-white students in her child’s grade were assigned to the same class in lower school.

Another father, whose daughter recently graduated from the middle school, said classes have been segregated for as long as she was enrolled there and was conspicuously in effect during the 2016-17 year.

Once the policy — which Kassen claimed was only in effect last year and limited to 7th and 8th grades — became common knowledge in early June, enraged parents went on the offensive.

“They had a couple meetings with parents and there was a lot of buzz and outrage and yelling,” said another parent at the school.

“Everyone was saying, ‘We don’t think it’s necessary. These kids have been friends since kindergarten and nursery school. They don’t see color so why are you doing this?’

On June 12, Kassen — who made $403,039 in total compensation in 2016 — emailed parents explaining that the proposed class-placement policy would be reviewed.

Eight days later, he emailed again, stating that he would nix the policy, but would continue to keep “race as a critical, but not primary, determinant.”

Parents are unclear what that means, and Kassen refused to comment to The Post beyond providing emails sent to parents.

In the Wednesday missive to parents, he explained the policy was born from conversations with recent graduates who said the school could “create greater opportunities for connection and support.”

He points to a passage from the school’s handbook that states: “Research points to the academic, social, and emotional benefits to being in a classroom with others who share racial, ethnic, linguistic, and/or cultural backgrounds.”