The Sacrament of Holy Baptism

As the head of the family should teach it in a simple way to his household.

First

What is Baptism?

Answer.
Baptism is not simple water only, but it is the water comprehended in God's command and connected with God's Word.

Which is that word of God?

Answer.
Christ, our Lord, says in the last chapter of Matthew:

Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you.
(Matthew 28:19-20, ESV)

Secondly

What does Baptism give or profit?

Answer.
It works forgiveness of sins, delivers from death and the devil, and gives eternal salvation to all who believe this, as the words and promises of God declare.

Which are such words and promises of God?

Answer.
Christ, our Lord, says in the last chapter of Mark:

Whoever believes and is baptized will be saved, but whoever does not believe will be condemned.
(Mark 16:16, ESV)

Thirdly

How can water do such great things?

Answer.
It is not the water indeed that does them, but the word of God which is in and with the water, and faith, which trusts such word of God in the water. For without the word of God the water is simple water and no baptism. But with the word of God it is a baptism, that is, a gracious water of life and a washing of regeneration in the Holy Ghost, as St. Paul says, Titus, chapter three:

he saved us, not because of works done by us in righteousness, but according to his own mercy, by the washing of regeneration and renewal of the Holy Spirit, whom he poured out on us richly through Jesus Christ our Savior, so that being justified by his grace we might become heirs according to the hope of eternal life.
(Titus 3:5-7 ESV)

This is a faithful saying.

Fourthly

What does such baptizing with water signify?

Answer.
It signifies that the old Adam in us should, by daily contrition and repentance, be drowned and die with all sins and evil lusts, and, again, a new man daily come forth and arise; who shall live before God in righteousness and purity forever.

Where is this written?

Answer.
St. Paul says Romans, chapter 6:

We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.
(Romans 6:4 ESV)

(Go deeper with The Large Catechism - Holy Baptism)