Walter Scott, an important figure in the early Restoration Movement would teach children about salvation using the "five-finger method". Notice the elements that he includes:
Belief, Repentance, Immersion, Forgiveness, the Gift of the Holy Spirit, and Eternal Life.
(Source: Walter Scott, The Gospel Restored: A Discourse of the True Gospel of Jesus Christ, in which the Facts, Principles, Duties, and Privileges of Christianity are Arranged, Defined, Discussed, and the Gospel in its Various Parts Shewn to be Adapted to the Nature and Necessities of Man in His Present Condition, page 6.)
What would you include in your list? How should we teach children about the salvation that is available to us through Jesus?