Ask why Rudolf should be Rudolfina.
Because only female reindeer have antlers at Christmas. The males have dropped theirs by then.
Ask what names foreign countries have for Santa Claus. Or find out several, and ask which countries use those names.
Traditional Christmas meals / foods in other countries.
Who invented Christmas crackers. In which decade were the first Christmas cards sent. When was the last (official) white christmas in London ?
How many billion records of "White Christmas" have been sold ?
Or, if all else fails, get a book out of the public Library. If they haven't got one on their shelves, they can get one from another library for you.