Hi Artminot,
 
Are you asking about the origins of the Christmas holiday, or are you asking about the winter break holiday for your child's school?
 
If the latter, please contact your child's school for the most accurate answer to your question. If you don't have the school's contact info handy, and if located in the United States, you may research the contact info in SchoolFinder: http://www.education.com/schoolfinder/
 
If you're asking about the origins of the Christmas holiday, here is a resource you can review:  http://www.holidays.net/christmas/story.htm
 
I hope the above resources help in getting to the answer you seek.