Coming from very poor family situations, we can assume nothing about the level of knowledge of the one to be catechized. They may not ever have heard of Our Lord Jesus Christ.
When we came home and returned to our home parish, our children had been in Catholic schools since either kindergarten or even pre-school (for the youngest).
Our oldest was a Freshman in high school, and we enrolled her in the Confirmation classes. *She* was distressed by the level in her classes--which were geared to the bulk of the students that didn't know things like how many Commandments, the Lord's Prayer, and such, not having seen the insides of a church since First Communion (and for those who had, the local norm is not to have an Catechism between!).
It terrifies me to think what would have happened had she not joined me at an EC church . . .
hawk