Advent is known as “little Lent,” and prayer, alms, and sacrifices are an important part of the season. To help children participate in the true purpose of Advent (rather than treating it selfishly as a countdown to getting their presents on Christmas day), a visual teaching aid is most helpful.
For each small sacrifice or good deed done by a child during Advent, a piece of straw is added into the manger or creche. On Christmas day the Baby Jesus figure is placed inside the creche, and the prayers and sacrifices symbolized by the pieces of straw have added up to prepare Him a comfortable place to rest. This visually symbolizes the room for Jesus that we have prepared in our hearts by making sacrifices and doing good deeds for others.