The idea of Class Jumping involves the advancement of a person from a lower socio-economic class to one of higher standing. Many works are centered around the concept of class struggles and the measure of "how easy" it is to move from one class to another, that is to say a measure of class mobility.
Classes/Hierarchies in Readings
Schismatrix People in both the Shaper or Mechanist colonies were set in hierarchies. People born in certain families were more important than others. People in higher classes than others were usually more technologically advanced. Also, they had better schooling than those of the lower classes, and they usually held important political positions. It was not easy for a person to rise up the ranks because this was based mostly on bloodlines, but it was easy for some to lose all of their renown and sink in fame, much like what happened to the main character in this novel.
Linsday, to begin with is not truly a Shaper-- he has not been "re-shaped" and is simply a human who has undergone extensive training. The implication is made through most of the reshaped are superior to normal humans. He managed to excel most of those people by becoming more successful, and in many cases, living longer than them by running away. While he doesn't do better than everyone else through skill and talent alone, he does get lucky enough to transcend his "place" in life.
He, She, and It Schools and workplaces are split into different hierarchies. There is no 'royalty' system like there is in Schismatrix. A person with useful skills and talent had a higher paying job, more 'renown', and more priveleges of rank than a normal person would. The person's rank, or renown, also determines where his or her child would attend school; people with high ranks send their children to the best schools. Also, in this novel, high ranking individuals have a lot more access to advanced body modifications. Those modifications are needed to 'look nice' to others of lower classes. Also, those technological modifications are needed to have an advantage over the lower class people. People living in the 'Glop' have little access to these things because of their rank, and because the modifications cost a lot of money. In this sense, class jumping is very difficult. At one point in the novel, the protagonist is offered the opportunity to rise up a rank in her former company as a part of a bargain that turns violent. This illustrates the high stakes associated with such deals.
The Winter Market Lise is able to rise above everyone else because she followed her dream to become famous, despite her disabled body. Technology allowed her to overcome those odds and she rose from being a whiz-addicted nobody to a famous Hollywood superstar. Her artistic talent is coupled with the technology she uses to move. Poorer kids in the neighborhood are proud of her for what she has done with her life, and look up to her. The only person who doesn't approve of this is Case.