In The Giver, engineer, doctor, birthmother, and laborer are assignments.

In the community, people do not just choose their jobs as we do.  Instead, they are given assignments by the Committee of Elders.  It is a secret selection made by a committee that “took the responsibility so seriously that there were never even any jokes made about Assignments” (ch 2, p. 15).  The assignments are lifetime jobs. 

Engineers and Doctors were higher-profile assignments.  An Engineer would be responsible for designing and building structures, such as bridges.  This would be someone good at math who enjoys building things. A doctor would have much the same job as ours today.

Laborer and Birthmother are lower status jobs.  Birthmothers have the assignment for three years, and give birth three times.  They live in pleasant conditions, with good food and easy exercise.  However, they never get to see the children they give birth to.  Birthmother is “an important job, if lacking in prestige” (ch 7, p. 53).  After they give birth they become Laborers.  Jonas describes a girl in his class named Inger who is lazy and strong, and seems pleased with her assignment as Birthmother.

She would enjoy the three years of being pampered that would follow her brief training; she would give birth easily and well; and the task of Laborer that would follow would use her strength, keep her healthy, and impose self-discipline. (ch 7, p. 53)

Jonas does not know what assignment he wants.  He does not envy laborers, and he has no special talent or interest.  He is completely surprised when he is selected for an assignment he did not even know was possible: Receiver of Memory.

Lowry, Lois (1993-04-26). The Giver (Newbery Medal Book). Houghton Mifflin Harcourt. Kindle Edition.