Even the Grinch wouldn’t be this mean.

A sourpuss teacher in Rockland County ruined Christmas for a class full of second-graders this week, when she told them that there is no Santa Claus during a lesson about the North Pole.

The evil educator even told the youngsters — mostly 7- and 8-year-olds — that the presents under their trees were put out by their parents, and not St. Nick.

The stunning Scrooge-like behavior has caused a blizzard of outrage at the quiet George W. Miller Elementary School in Nanuet, where angry parents would like to see the teacher roasted like a chestnut over an open fire.

“If that happened to my daughter in her second-grade class . . . I’d be very upset,” said, Sean Flanagan, 48, whose child was in second grade at the school last year.

“If her brothers told her [there was no Santa], they would be punished. So I can’t imagine what should happen to the teacher.”

A nanny picking up a child at the school yesterday told The Post that anyone who tells kids that Santa doesn’t exist should get coal in their stocking.

“It’s outrageous that a teacher would strip a child of their innocence and try and demystify something,” said Margaret Fernandez, 59.

A grandmother of a kindergartner said, “I think this is awful.

“If it happened to my granddaughter, I’d tell her her teacher made a mistake, and there is a Santa,” she added.

The unidentified teacher reportedly made her anti-Santa comments Tuesday during a geography lesson, when students told her that they knew where the North Pole was because that’s where Santa lives.

Yesterday, school officials wouldn’t discuss the Christmas incident or say if the teacher would face any discipline.

District Superintendent Mark McNeill released a brief statement, saying only, “This matter is being addressed internally.”

One Christmas official was commenting on the record yesterday — Santa himself!

“When I read what happened at the school, I had an opinion that I don’t feel would be printable,” said a still-jolly St. Nick, who was posing for pictures with kids at the Palisades Mall. “I do feel it is unfortunate that this teacher has lost the spirit of Christmas in her heart.

“It is important to keep that spirit alive so that Santa can be real for everyone.”

The teacher’s attempt to sleigh Santa even got a reaction from the granddaughter of Virginia O’Hanlon, whose famous 1897 letter to the New York Sun asking if Santa was real drew the legendary response, “Yes, Virginia, there is a Santa Claus.”

“My grandmother was a teacher for years, and I don’t think she ever had a problem answering that [Santa question],” Mary Blair, 69, told The Post.

“The most real things in the world are things that you don’t see or touch,” she added, “and they are the things that mean the most — love, kindness and generosity.”

Additional reporting by Frank Rosario