Why does Scout stand up for Walter?

In Chapter 2, it is Scout's first day of school. During lunchtime, Scout's teacher, Miss Caroline, notices that Walter Cunningham doesn't have a lunch. Walter tells Miss Caroline that he left his lunch at home and Miss Caroline attempts to give him a quarter to pay for his lunch. Walter shakes his head and refuses the quarter. Confused, Miss Caroline attempts multiple times to give Walter a quarter, and Walter continues to reject her offer. One of Scout's classmates whispers in her ear, "Go on and tell her, Scout." (Lee 26) Scout's classmates must look up to her because they persuade Scout to explain Walter's situation to Miss Caroline. Scout attempts to explain to Miss Caroline that Walter comes from a poor family who refuses to take anything they cannot pay back. Instead of fully explaining Walter's background, Scout assumes Miss Caroline understands what she means when she says, "he's a Cunningham." (Lee 26) Eventually, Scout tells Miss Caroline that she's "shamin'" him and Walter can't repay her with stovewood. Miss Caroline loses her patience with Scout and punishes her by patting her twelve times on the palm with a ruler.