In order to understand the answer to this question, it is equally important to understand the cultural context of the question itself. Essentially, the Freedom Writers' novel is based in California, where gang mentalities are rampant. Often times, the gang mentality dictates that you hate rival gangs and even attempt to kill them if given the chance. For this reason, many of the students who are portrayed in the novel did not have a love or understanding of their fellow classmates. In fact, they despised their fellow classmates and did not want to learn with or about them.
Social psychology explains that this mentality is a protective mechanism for the in-group bias. This means anyone who does not fit the mold of the in-group is characterized, often times negatively, to adjust for preconceived notions about them. Learning with and from those that a cultural group does not understand will often fly in the face of commonly held beliefs about that group. To that end, the learning never takes place out of fear and ignorance.