If a child does not like the assignment given at the Ceremony of Twelve, there is nothing he or she can do about it. Children do not choose their assignments. They are observed carefully by a committee that determines what their assignment will be.
Long before they are twelve, children begin to serve volunteer hours after school. They can go wherever they like, but the committee tracks these hours carefully. They cannot get an assignment unless they have completed the required hours (a very shameful thing indeed).
Jonas’s father describes how he spent most of his volunteer hours playing with babies in the Nurturing Center.
“But again and again, during free time, I found myself drawn to the newchildren. I spent almost all of my volunteer hours helping in the Nurturing Center. Of course the Elders knew that, from their observation." (ch 2, p. 15)
The elders meet “for long hours with all of the instructors” to determine what jobs each child should have. When Jonas asks if any Elevens are ever disappointed with their assignments, they tell him no, because “the Elders are so careful in their observations and selections" (p. 16).
The children are usually in suspense before the ceremony, and not sure what they will get. Whatever job they get is the job they’re stuck with. The one questions orders in the community.
Lowry, Lois (1993-04-26). The Giver (Newbery Medal Book). Houghton Mifflin Harcourt. Kindle Edition.