Pastor walks his children through Westminster Shorter Catechism question 107—especially explaining how God's glory shapes our prayers' purpose, petitions, and power.
Q107. What doth the conclusion of the Lord's prayer teach us? The conclusion of the Lord's prayer, which is, "For Thine is the kingdom, and the power, and the glory, forever, Amen," teacheth us to take our encouragement in prayer from God only, and in our prayers to praise Him, ascribing kingdom, power and glory to Him. And in testimony of our desire, and assurance to be heard, we say, "Amen."