Page 90: What does Atticus mean when he says, “It’s a sin to kill a mockingbird”? Predict how this idea will become a major theme in the novel? Who are the metaphorical “mockingbirds” in the story?
Atticus tells Scout and Jem they can shoot their air guns at tins cans and bluebirds, but that it is a sin to kill a mockingbird. Miss Maudie affirms this, saying to Scout, "Your father's right. Mockingbirds don't do one thing but make music for us to enjoy. They don't eat up people's gardens, don't nest in corncribs, they don't do one thing but sing their hearts out for us. That's why it's a sin to kill a mockingbird."
This becomes a theme in the novel in regard to Tom Robinson's trial. An innocent being accused and tried for an act he didn't commit.
The two metaphorical mockingbirds in the story are Tom Robinson and Boo Radley.
http://www.gradesaver.com/to-kill-a-mockingbird/study-guide/summary-chapters-7-12
