"How do we explain the Sacrament of Reconciliation to children?"
Developmental psychologists and educational theorists describe a change that occurs in a child's thinking around first or second grade. Jean Piaget called this the beginning of the "concrete operational" period of reasoning. At this time, children have mastered the concept of cause and effect. They understand that everything in the world works according to particular rules. For example, if you perform a magic trick for a preschooler, he or she might say, "Wow, you're magic!" But if you perform the same trick for a child in second grade, the child will likely ask, "How did you do that?" These children know that there's no such thing as magic, and that everything in the natural world must follow rules. Children this age can be notorious tattletales, because as they begin to organize their view of the world according to rules, they feel more secure if they feel the people around them are following the rules.
This rule-based thinking makes this age an opportune time to introduce God's guidelines for how to live. Children who understand cause and effect also understand the difference between right and wrong. They know there are rules for how things work in the natural world and also rules at home, school, and in the community. It's natural, then, that we would introduce God's guidelines for our moral and spiritual lives.
However, as children become aware of God's rules, they will also become painfully aware of the times we fail to be all that God made us to be. It's important for them to now that God forgives us when we are sorry for our sins, and that he will help us to do better. Children in the "concrete operational" stage are just that -- very "concrete." They need to experience a new concept with their senses in order to truly understand it.
The Sacrament of Reconciliation is a concrete experience of God's forgiveness, a reminder that God loves us no matter what, and a vehicle for his grace, which will help us to do better -- to become more and more the people God made us to be. We should never sell our children short by expecting less than their best, but we don't always know what their best is. The Sacrament of Reconciliation gives them a chance to experience God's forgiveness when they are aware of their sin, and to know that God will work with them as they grow into the people he has called them to be.
This is why the Church, in her wisdom, tells us that even those who will celebrate First Eucharist as children must celebrate First Reconciliation first. Although most children this age probably do not have mortal sin, they have reached the age of reason, and it is important that they allow God to make them ready to experience the closeness they can feel with Jesus in the Eucharist. This forgiveness and the reassurance that we are truly in God's friendship helps us to better enter into true communion with him.