Catholic Activity: Christkindl Brief or Letter to the Christ Child
An Austrian custom practiced in the Trapp family was the writing of letters to the Christ Child during Advent.
And there is still one very important thing to do for Advent. According to Austrian custom, every member of the family writes a letter to the Holy Child mentioning his resolutions for the weeks of Advent and listing all his wishes for gifts. This "Christkindl Brief" (letter to the Holy Child) is put on the window sill, from whence the Guardian Angel will take it up to heaven to read it aloud to the Holy Child.
Activity Source: Around the Year with the Trapp Family by Maria Augusta Trapp, Pantheon Books Inc., New York, New York, 1955