Picture in your mind, and it shouldn’t take much imagination, a young boy participating in the priesthood function of the Sacrament. He lowers his head during the prayers and then gleefully hands out the water and bread to the congregation. Just like what happens every Sunday, he returns to the cloth covered table and sets down the silver trays he passed around the room. There is nothing unusual about the actions.
What is relatively different is the boy. He is far from unable to perform normal tasks, but his mental capacity is abnormally limited. During any other time he won’t sit still without trying to talk to whoever will lend him an ear. Despite his age, his thoughts and actions are far closer to a person younger than Priesthood age. Often he has to be kindly reminded his behavior is not appropriate, although lacking any serious disruptive nature.