This section of the novel occurs in Chapter Eight, and is when, rather disappointingly, Jem has to concede that it is not snowing hard enough to yield enough snow in order to make a snowman from the snow that has landed in his garden. However, never the one to be put off by such facts, Jem determines to take the snow from Miss Maudie's garden, asking her permission to take it and transfer it back to his own yard. Even then it is clear that there is not enough snow. Jem therefore collects equal amounts of earth, and uses this soil to construct the first layer of the snowman that they make, before finally using the snow to cover up the earth to give the appearance that they have made a snowman, which bears a rather uncanny resemblance to Mr Avery:

Jem scooped up some snow and began plasting it on. He permitted me to cover only the back, saving the public parts for himself. Gradually Mr Avery turned white.

In a novel that is so much about racism and the importance of the colour of one's skin, having a snowman that is black underneath and white on top points towards the superficiality of such distinctions, and suggests a common humanity that is shared by all, no matter what the colour of the top layer of skin somebody has. Note too, that the snow that falls is incredibly unseasonable and something of a hostile intervention of nature. This, along with the fire that burns Miss Maudie's house, threatens the characters, but the characters are able to use their natural goodness and potential to convert this threat into an opportunity through their goodness. The significance of the snowman is through the way in which Jem uses black earth to build it and how this links to the theme of racism in the novel.

Since there was very little snow and it did not have much texture, Jem asked Miss Maudie if they could use some of hers. She gladly acceded since she was disgusted by it for killing her precious plants. She told Jem and Scout to remove it by using a peach basket they would find under the house.

The snow was slushy and, because they had collected very little of it, Scout asked Jem if they were going to make a snow baby. Jem told her that they were going to build a 'a real snowman.'

Jem started digging out dirt behind the woodpile which he loaded into the laundry basket. He then took it to the front yard. Once he had collected five baskets of ground, he stated that they could start building their snowman by using the dirt and the two baskets of snow they had collected. Scout commented that the whole concoction looked like a mess but Jem assured her that it would not be so once he had started working on it.

Jem then used the dirt to construct a torso which elicited the following comment from Scout:

“Jem, I ain’t ever heard of a nigger snowman,” 

He told her that the snowman won't be black for long and proceeded to use peach tree shoots which he plaited to form what Scout calls 'bones,' to be covered with dirt. Scout mocked Jem's first attempt by comparing it to a girl called Stephanie Crawford who apparently had thin arms and a big stomach. Jem proceeded to fatten up the arms. He then formed a large stomach and stood back to take a look at the result, rhetorically stating that, 'Mr Avery is sort of shaped like a snowman.'

Jem then used snow to cover the dirt, allowing Scout to do the back whilst he focused on the 'public parts.' When the dirt was completely covered, he used small pieces of wood to indicate the mouth, eyes, nose and buttons. He then completed the creation by adding a stick of stovewood.

Jem then called Atticus to view his masterpiece and Atticus complimented the two children for having cleaned the backyard by removing the snow. The remark embarrassed Jem. Atticus grinned and remarked that Jem should alter the snowman since its appearance was defamatory. Mr Avery would feel insulted if he should see himself represented in such a way.

Jem was not keen in removing any of the snow from the stomach and, instead, rushed over to Miss Maudie's house returning with her sunhat and hedge clippers. He placed the hat on the snowman's head and jammed the clippers into the crook of its arm. The alteration pleased Atticus. Miss Maudie would later remark that Jem's creation was 'an absolute morphodite' which suggested that his work depicted a creature that had both male and female organs.

There are numerous suggestions about the symbolic value of Jem's creation. Some commentators believe that it depicts the fact that we are all the same or that whites and blacks have characteristics of one another. Some commentators argue that, within the context of the novel, it mocks bigotry and racism since we are all, essentially, alike. Others believe that Harper Lee had no further intent but to indicate that Maycomb County did not experience much snow.

Whatever our interpretation, Jem and Scout clearly enjoyed the exercise, especially because they could, if only for a brief moment, mock the unpleasant Mr Avery.  

The building of the snowman, which involved a lot of dirt and a little bit of snow, helped establish the evolving relationship of Jem and Scout to the town. Their intent was to mock a neighbor, Mr. Avery, that they did not particularly care for. When Atticus saw what they had done, he recognized Mr. Avery in the snowman and had the kids disguise it with Miss Maudie's hat and broom. 

The fact that Atticus did not direct them to destroy the snowman tells us several things. One, Atticus acknowledges that there are people that deserve a little bit of mockery, but that the mockery must be done privately. Two, Jem is a very creative, determined kid whose efforts should be appreciated but directed in socially appropriate ways. 

Symbolically, the author might be suggesting that although people may look normal on the outside, they might be "dirty" on the inside, much like the snowman. 

They used both snow and soil to build the snowman.

The different layers of snow and dirt seem to give a bit of foreshadowing of the racial unrest that will shake up the town.

In the effort to disguise the color of the snow-man and the likeness to Mr. Avery, Jem runs over to Miss Maudie's house and snatches her hat and hedge clippers to decorate the snowman/woman.