BAPTISM IS THE FIRST ORDINANCE OF THE GOSPEL.Start by having the children say the 3rd and 4th Article of Faith.
Place pictures of Jesus being Baptized GAK 208, Boy being Baptized , and Girl being Baptized on the board
(3) We believe that through the Atonement of Christ, all mankind may be saved, by obedience to the laws and ordinances of the Gospel.
(4) We believe that the first principles and ordinances of the Gospel are: first, Faith in the Lord Jesus Christ; second, Repentance; third, Baptism by immersion for the remission of sins; fourth, Laying on of hands for the gift of the Holy Ghost.
What is an ordinance? That is a big word and we do need to understand it.
"In the Church, an ordinance is a sacred, formal act performed by the authority of the priesthood. Some ordinances are essential to our exaltation. These ordinances are called saving ordinances. They include baptism, confirmation, ordination to the Melchizedek Priesthood (for men), the temple endowment, and the marriage sealing. With each of these ordinances, we enter into solemn covenants with the Lord.
Ordinances and covenants help us remember who we are. They remind us of our duty to God. The Lord has provided them to help us come unto Him and receive eternal life. When we honor them, He strengthens us spiritually.
When Jesus was on the earth, He performed ordinances to help people. He healed the sick and made the blind to see. He made the deaf able to hear and even brought the dead back to life. He gave the sacrament to His followers.
Jesus has given to men who hold the priesthood the power and authority to perform ordinances. Worthy men and boys who hold the priesthood can perform ordinances. They perform the ordinances to bless us and help us to become like our Father in Heaven. The ordinances help us prepare to return and live with Him.
Because Jesus has given the priesthood to men on earth today, we can receive many blessings in our lives. We can be baptized, receive the gift of the Holy Ghost, and be sealed with our families forever.
Baptism is the first ordinance of the gospel of Jesus Christ. Before being baptized, people must have faith in Jesus, repent of their sins, and want to do the things that Jesus taught."
I really like the May 2009 Sharing Time from the Friend
John 3:5 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.
Being "born of water and of the Spirit" means to be baptized and to receive the gift of the Holy Ghost.