Elena, a Puerto Rican American, endures a lot of prejudice because she attends a predominantly African American school, lives in a poorly-looking apartment block, and simply is not white. First, Elena is teased by the girls in her ninth-grade class by being called "Skinny Bones" and because she isn't as good of a rope jumper as the others.
"Gail, the biggest of the black girls who had the other end of the rope yelled, 'Didn't you eat your rice and beans and pork chops for breakfast today?'" (Lines 45-46).
The allusion Gail makes to Elena's traditional menu is then used against her as the other girls chant "pork chop" over and over again.
Another type of prejudice that Elena encounters is the stigma with living in El Building, which is a large, gray block of apartments that houses many unemployed people. The lack of privacy is one thing to have to deal with, let alone the fact that she describes it as follows:
". . . El Building. . . looked particularly ugly, like a gray prison, with its many dirty windows and rusty fire escapes" (Lines 386-387).
Living in El Building would not be a big deal if it weren't for the fact that her best friend's mother judges her by it and by her culture. The ultimate portrayal of prejudice is exactly at the moment she meets Eugene's mother and is turned away for being living in El Building and not being white. Eugene's mother doesn't say it explicitly, but her rude attitude towards Elena clearly proves that she does not want her white son from Georgia handing out with any minority whatsoever.
"'You live there?' She pointed to El Building. . . she looked intently at me for a couple of heartbeats, then said as if to herself, 'I don't know how you people do it.' Then directly to me: 'Listen. Honey. Eugene doesn't want to study with you. . . No need for him to get close to people--it'll just make it harder for him later. Run back home now'" (Lines 385, 394-396).
When Eugene's mother says to herself "I don't know how you people do it," she seems to be referring to how they live in that building the way they do. This is showing prejudice against the poor quality of the building as well as for its culture inside. Then when she dismisses Elena, she proves her prejudice against Elena as a minority.