What are three ways in which "To Kill a Mockingbird" is used as a metaphor in the story and two ways it's used in the film?

The title of the book refers to the moment in which Atticus tells the children that "it's a sin to kill a mockingbird," by which he means that it's a sin to kill something that's innocent and is trying to do something nice.

This metaphor is present throughout the story in many different ways. For instance, when Jem, Scout, and Dill sneak out to follow Atticus to the jail, they are shocked to find him...

The title of the book refers to the moment in which Atticus tells the children that "it's a sin to kill a mockingbird," by which he means that it's a sin to kill something that's innocent and is trying to do something nice.

This metaphor is present throughout the story in many different ways. For instance, when Jem, Scout, and Dill sneak out to follow Atticus to the jail, they are shocked to find him being confronted by a mob. Among the reasons that this is jarring is because they knew many of the people in the mob and had thought them to be good people. For Scout, this is one of the first times that she realizes how someone you think you know can change so dramatically and become a source of confusion or danger, which chips away at her innocence.

A very strong example of this metaphor is the outcome of Tom Robinson's trial. When Tom goes into Mayella's yard, he is innocently trying to help her until she starts making advances. Despite Atticus' strong defense that proves his innocence, Tom is still found guilty by the white community. In this case, Tom was trying to do something to help another person, which ends up costing him his life.

Finally, Scout and Jem being attacked at the end of the book is perhaps the most obvious example of the title. Throughout the story, the children are symbolic of innocence and the slow erosion of innocence that takes place as we grow up. Given that, their being attacked by another person in the community shatters the illusion of safety and the innocence that they can never get back.

Because the film is more or less faithful to the book, any examples found in the movie are also in the novel. Nevertheless, some things are more powerful when depicted visually, such as Jem's strong reaction to outcome of the trial. Throughout the novel, Atticus teaches the children the importance of doing the right thing and he is a hero to Scout and Jem. For that reason, Jem becomes very upset when Tom is found guilty despite his obvious innocence. Jem's view of the world is less innocent than Scout's but he had put his faith in people doing the right thing. The outcome of the trial is the first time that he sees how unfair the world can be, which takes away a great deal of his innocence and harms his faith in doing what's right.

Finally, the film does an excellent job of using the title as metaphor when Scout is finally introduced to Boo. For the duration of the film (and novel), Boo is a mysterious but obviously emotionally fragile person. By saving Jem and Scout, he puts his physical and emotional safety at risk, particularly if he is forced to endure a trial. In this case, Boo was doing something to help another person, which could have ultimately led to his whole world collapsing around him. This scene is particularly powerful given the ways in which he is almost literally dragged out of the shadows and thrust into a very dangerous world.