The actual birth date of Christ is unknown but we have chosen December 25th to celebrate. Children should understand why they receive gifts on December 25th. It is because the Wise men gave Mary gifts of Gold, Frankincense and Myrrh for Jesus. The gifts were precious and had spiritual meaning.
Gold is for royalty. The Wise men gave this gift as they recognized Jesus as being a King, they had followed His star, it leads them to the place He was in, and when they found Him, they offered their gifts to Him.
Frankincense is connected to worship and the Jewish People burned it at the altar when they prayed to God. Jesus has a Devine nature and the Wise men knew that He came from God so this is why that gift was offered.
Myrrh was a perfume. It was used for burials to prevent the smell of decay following death. They knew that this Royal, Devine king would die for the sins of the World so they offered Him this gift.
Luke 2:10-11 do not be afraid, for behold, I bring you good tidings of great joy, which will be to all People. For there is born to you this day in the City of David a Savior who is Christ the Lord.