Uncle Jack gets Scout and Jem air rifles as Christmas presents, and Atticus instructs the children to not kill any mockingbirds. Miss Maudie elaborates on Atticus's comment and tells the children that it is considered a sin to kill a mockingbird because they are harmless, innocent creatures that do not bother anybody. Throughout the novel, mockingbirds symbolically represent innocent, vulnerable individuals who rely on morally upright people to protect them. Atticus's brief message becomes a significant life lesson to his children, who learn the importance of protecting symbolic mockingbirds.
The air rifle symbolically represents an important stage of Scout's moral development. A rifle is a dangerous weapon that should be handled by adults. However, an air rifle is similar to the weapon it is designed after but is made for children and is significantly less dangerous. Similar to Scout, who is gradually maturing and developing into a grown individual, the air rifle symbolically represents her youth and the current stage of her moral development.
When Scout receives the air rifle, she is too young and naive to understand the nature of Maycomb's prejudice or fully comprehend Atticus's lesson regarding mockingbirds. Scout is still an innocent child who does not understand the adult world, which corresponds to the air rifle's symbolism. Later, in chapter 10, Scout will witness her father shoot and kill a rabid dog using a real rifle. Atticus's rifle symbolically represents the lengths he is willing to go to protect the innocent citizens of Maycomb and challenge their racist culture. Scout has not reached her father's level of understanding but hopes to follow in his footsteps, which corresponds to the symbolism of the air rifle.