The perfect Act of Contrition prayer is from the 1885 Baltimore Catechism.
I treasure having learned it in grade school because it really seemed to "cover" everything: my love for God, my love for family, and my true sorrow for all my sins.
Learning it is easy when you have someone to help you, or when you have an audio recording as with St. Anne's Helper Downloads and CDs.
Next to the prayers of the Rosary. it is the first most important prayer to learn. We use it in receiving the sacrament of Penance and for a nightly examination of conscience. It is one of the prayers we should pray every day, especially when in danger of death.
Be sure to teach it to your little ones long before you teach the other Acts as they are so similar that it can be confusing for little ones to learn the other prayers before their first confession.
It has a phrase that is super similar to the Act of Charity, so have your children wait to learn it till after they learn the Act of Contrition well and perhaps even after they are handy going to confession.
This version is the same prayer that was published in the Baltimore Catechism in 1885 and covers the most intentions with the fewest words.
The perfect Act of Contrition is the best prayer that Catholics use for the Sacrament of Penance (Catholic Reconciliation) and at night before retiring with Rosary and a short examination of conscience.
It covers the contrition necessary to cover a mortal sin till the penitent can go to sacramental Confession. In this way it is one of the most important Catholic prayers when one is in danger of death!
What makes it perfect?
It is a perfect act because
Loving God makes the act perfect.