Parents said first grade children at Cedar Hill Elementary School in Montville had to be consoled after the incident, which was sparked when one pupil asserted Santa Claus was real.
The child’s statement is thought to have prompted an outburst from the teacher in question, who then reportedly went on to debunk several other myths including the Tooth Fairy and the Easter Bunny.
Myra Sansone-Aboyoun, a mother of one child in the class, said she had to comfort her six-year-old daughter after she told her what had happened at school that day.
“I was heartbroken,” she told News 12 New Jersey. “You know, my daughter is the hugest believer in the whole Christmas spirit - Santa, giving.”
Another parent with a child in the class, Lisa Simek, wrote on Facebook the teacher had “completely unleashed” on pupils.
“She told them Santa isn’t real and parents just buy presents and put them under their tree. She told them reindeer can’t fly and elves are not real,” she said.
“She did not even stop there: the tooth fairy is not real because mom or dad just sneak into your room in the middle of the night and put money under your pillow, same goes for the Easter bunny.
“A grown woman tried to crush our six-year-old’s spirit, along with the spirits of the other 22 kids in [Cedar Hill’s] first grade class.”
Michael J Raj, the principal at Cedar Hill Elementary, later apologised for the teacher’s behaviour in a letter sent to parents.
“As a father of four myself, I am truly aware of the sensitive nature of this announcement,” he said.
“If the conversation comes up at home over the next few days you can take appropriate steps to maintain the childhood innocence of the holiday season.”
Montville schools superintendent Rene Rovtar later said the substitute teacher, who has not been named, was no longer working in the district.
“A student had written that Santa is real. She felt compelled, somehow, to tell a student that Santa is not real,” she told NJ.com.
“It's obviously something we're deeply concerned about in terms of her judgment.”
More about: Santa