Why does Atticus tell Jem and Scout they have to change their snowman?
In one of the most humorous scenes throughout the novel, Jem and Scout attempt to construct a snowman in Chapter 8. Despite having barely enough snow to build a proper snowman, the children collect snow from Maudie's yard and use it to cover balls of mud in order to build a snowman. As was mentioned in the previous post, Jem constructs the snowman in the likeness of their overweight neighbor, Mr. Avery. When Atticus returns home from work, he laughs as he tells Jem that he "perpetuated a near libel in the front yard." Atticus then tells Jem that he needs to change the snowman so that it does not resemble a caricature of Mr. Avery. Immediately, Jem runs over to Maudie's yard to grab hedge-clippers and a sunhat. Jem then puts Maudie's belongings on the snowman which makes the snowman resemble her instead of Mr. Avery.
Atticus thinks Jem should change the snowman because it too closely resembles their neighbor, Mr. Avery, and not in a very complimentary way either. "Using bits of wood for eyes, nose, mouth, and buttons, Jem succeeded in making Mr. Avery look cross" is the way Scout describes Jem's creation. Even Miss Maudie is a bit appalled, encouraging Jem and Scout to modify the snowman so as not to hurt anyone's feelings. Because Mr. Avery "is sort of shaped like a snowman," his feelings would be hurt with this caricature.
Jem models his snowman after Mr. Avery, who stays in one of Miss Maudie's rooms. Atticus has him change it because he fears that it might be construed as an insult. This stays true to how Atticus made Jem, Scout, and Dill stop their plays when he realized they were mimicking the lives of the Radley's. It too is Atticus's way of reminding the children that their actions have consequences. They might think the snowman is humorous, but Mr. Avery might not share that same sentiment.