How did Jonas father know that he was going to be assigned as a nurturer the giver?

Jonas's father knew that Jonas was going to be assigned as a nurturer because he saw Jonas's name on the list of assignments. In the world of The Giver, assignments are carefully chosen by the Elders based on each individual's qualities and aptitudes. Jonas's father worked in the Nurturing Center and noticed Jonas's qualities that would make him a good nurturer.