The problem is when the children came home telling parents what the teacher said it caused a social media outcry from the parental community.
My impression from the reaction of parents is they no doubt preferred to tell their children about Santa in their own time as compared to the teacher bursting the imaginary bubble of six and seven year old children.
Be that as it may, this brings up some things worth talking about--especially for the Christian community.
When my wife and I raised our two children we chose never to pretend Santa was real. As my children became old enough I simply told them Santa was a cartoon figure. While it was fun for them to use their imaginations as they might like at their young age, they nonetheless knew Santa was not real.
We proceeded to tell them the truth about the tradition of St. Nick and how the idea of Santa became associated with Christmas (here is a good article on a Biblical view of Santa).
One thing I never wanted to do was to sow any seed of doubt in the minds of my children concerning the real meaning of Christmas. I wanted them to know the modern idea of Santa was a myth while the history of the Bible concerning the birth of Christ was real.
One thing we must do as Christian parents is never grieve the Holy Spirit. If we are going to celebrate Christmas at all, then the only appropriate way to do so is to exalt the Lord Jesus Christ.
He must be front and center in our celebrations. Indeed, enjoy the season as you make much a do about the birth of the most important person in history. Carefully take the time to teach the history of his birth to your children. Guide them into the awe and wonder not of an imaginary fellow in a red suit, but of the miracle that is Christmas--God came to us at Christmas as a helpless little babe lying in a manger!
As J.I. Packard said it, "The Almighty appeared on earth as a helpless human baby, needing to be fed and changed and taught to talk like any other child. The more you think about it, the more staggering it gets. Nothing in fiction is so fantastic as this truth of the Incarnation."
You will never make a mistake teaching your children the truth and when it comes to Christmas they need to know the real reason for the season in all its purity and wonder.