This scene is more symbolic of a great many issues related to social identity and African Americans in the latter half of the 20th century.  The literal conception of the scene is that African- American children have conditions that confront their childhood narratives that are different from White children.  Certainly, Hansberry's choice of a rat is unique in its own right.  It could have been a field mouse, or a bird, but in choosing a "rat," Hansberry identified an animal that is closely associated with squalor, poor living conditions, and overall challenge.  It is understood in the context of its presentation that rats don't live in Clybourne Park, or areas with a large concentration of White population.  This indicates a fundamental difference in the lives of children who live where the Youngers do.  Additionally, the rat is "trapped."  This is symbolic of how the social and material conditions configure the lives of many children of color.  Travis is chasing the rat with his friends, which is symbolic of the myriad of forces that are "chasing" and seeking to "trap" children of color in America.  This is a statement of the reality facing African American children:  Neighborhoods that might lack basic social services, schoolhouses that represent "the corridor of shame," lack of employment opportunities, a severe lack of institutional response, combined with a social and economic focus that poses challenges for African Americans, in particular African American children, is the reality that many faced at the time of Hansberry's writing, and still face today.  These forces work in tandem and in isolation to treat African- American and other children of color, or any child facing such a reality, as Travis and his friends chase the rat.  Final point being made in this scene might be how much a change is needed.  In any social setting where kids have to entertain themselves by chasing a rat, adults have to acknowledge that there is a fundamental problem in these conditions.  There must be a change, a reorientation that allows these situations to be remedied, for while Travis chases the rat today, he, himself, might be chased in the near future.