What is the rising action in Roll of Thunder, Hear My Cry?
There are many theories of dramatic structure that include "rising action." For the sake of this answer, I will use Freytag's Pyramid, specifically, to analyze the plot of this story. In Freytag's Pyramid, there are five segments to consider: exposition, rising action, climax, falling action, and conclusion. The rising action is defined as the portion of the plot that builds up to the climax. During the rising action, the author builds on initial exposition by using developing relationships, twists and turns, and various conflicts that lead the reader to the climax of the story: i.e. when all of these elements come to a head.
In Mildred D. Taylor's Roll of Thunder, Hear My Cry, the conflict begins to build with the description of the differences between the treatment of black and white families. The black families are dependent on the white families who own businesses (like the Wallaces' store). When the Wallaces start leading night raids and allowing miscreant behavior, Mama calls for a boycott of the store, which causes unrest between the communities. When word gets out that Mama suggested the boycott, Papa is shot in retribution. When Mr. Morrison beats up some white men, it's feared that the Wallaces' night raiders will come for him next.
From these events, we can see a building tension from one incident to the next—which is why this is called the "rising" action.