There are 25 ornaments that we hang on the tree. One each night counting down until Christmas. Each ornament contains a prophecy about Christ in the old testament and its fulfillment in the new. We started this tradition on Bo's second Christmas and the little ones look forward to hanging a new ornament each night.
The most exciting advent countdown we do with the children is hiding the small items each night that they then look for with their flashlights. Each item has a corresponding bible passage to go with it and the boys love to find the box containing the item with their flashlights.
This year I am ordering some of the Samaritan's Purse charity gifts and wrapping a picture of the gift and placing it under the tree with "To: Jesus" written on it. We will open the gift on Christmas and sing Happy Birthday to Jesus. This verse will be written on the card:
...Inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me." Matthew 25:40