A football player at practice. The image is black and white except for the red of the player's uniforms. The camera has caught a player balancing on one foot, almost like he's hanging in the air.

Source: “Toe the Line,” Barry Lenard, Flickr

When writing an expository essay, you need to distinguish between the controlling idea or thesis of the essay and the more specific topic of each section. Just because you are writing about a football game does not mean that your experience playing football in sixth grade is relevant. Football may be the general topic, but that doesn’t mean that any and every thought about football that comes into your head is relevant to the topic of the section you are writing.

A player resting after a scrimmage in a football game. The image is somber and dark, except for the player's purple jersey.

Source: “Football Scrimmage,” Sewanee: The University of the South, Flickr

So how do you make sure that you are sticking to your section topics throughout your writing? The secret to staying relevant is to pay attention to your topic sentence. The topic sentence puts a fence around a section and keeps it on topic. Let’s hope your topic sentence isn’t something like this: “I’m going to write about football.” This topic sentence puts a very big fence around what follows. Everything about football would be relevant. That’s a bad topic sentence and is going to lead to bad writing.

If your topic sentence states “football is a moneymaking sport for high school athletic programs,” then it fences in information about making money and keeps out anything else. Information about football being good physical training or about football equipment or about football rules is going to be irrelevant. Those topics might be included in a general essay about high school football, but each would have its own section (of one or more paragraphs) and its own topic sentence.

photo of young women playing flag football on a football field. Coaches and an umpire looks on in the background.

Source: “Girls Just Want to Have Fun”, Carolyn Todd, Flickr

If you have a range of information you want to include in an essay about football, you need to cluster the information according to topics and head each cluster with a topic sentence. In the practice exercise below, you will read several possible sentences for an essay. See if you can choose the topic that’s most relevant to each sentence.

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A crowd of blue and gold football helmets

Source:“Go Blue!”, Andrew Morrell Photography, Flickr

All of the information above is relevant to football, but it will only be relevant to one of the topic sentences. If the topic sentence is “You can make good friends playing football,” information about cardiovascular fitness is not relevant.

In each paragraph that follows, one sentence has jumped the fence and ended up in the wrong paragraph. Locate each stray sentence and click on it. If you choose correctly, the sentence will highlight.

High school football is a huge event in some small towns. Almost everyone comes to the games, and the whole town celebrates when their team wins. The students who are on the football team are local heroes when they do something special in a game. People even charter buses to travel with the team to out-of-town games. For pro games, people travel by plane to be able to watch their team play at an out-of-town field.

Pro teams also have very dedicated fans. However, since most pro teams are in cities, the fan base is bigger and the connection of the fans to the team is less personal. Fans might congregate in a local restaurant or bar or at someone’s home to watch their team on television. Sometimes there is a park or a vacant lot nearby where groups of people can play pick-up football games; sometimes games are played in someone’s yard. Really dedicated fans wear team colors to the games or even just to watch the game on television. When a team wins a big game like the Super Bowl, the city celebrates as if it is an official holiday with parades down the main streets.

Neighborhood football games are a way for people to spend time together and build a sense of community. Lots of high schools sell bumper stickers with the local mascot on them so people can show support for the team as they drive around town. Spectators often come with folding chairs and even bring picnics to watch a neighborhood game. Also, it is in the spirit of the game for the players to have some refreshments before, after, and even during the game. The point of the game is mostly to have a good time. Winning is not that important.

A football team charges out of a cloud of blue and white smoke

Source:“Put On,” beX out loud, Flickr

Topic sentences can help you sort out your information so it is located in a section where it will be relevant. Topic sentences emphasize to a reader (and remind you as a writer) what subtopic is being discussed in each subsection of the essay. Sometimes a writer implies a topic sentence rather than including one in the written essaybut it still indicates a subtopic. Relevance has to do with information being used where it will make a difference.