A topic sentence usually comes at the beginning of a paragraph. It guides the reader by focusing attention onto 1) a specific topic/idea and 2) presenting a controlling idea, which is usually an attitude, angle or debatable point. Thus, topic sentences DO MORE than simply state facts!!!
Also, they set the tone for the paragraph and as they communicate its main idea and angle, they should also related back to and advance the thesis of the essay.
Examples: (Some are not great topic sentences...you tell me which are weak.)
- Topic Sentence: The dedication of the mayor is making Boston Harbor one of the cleanest harbors in North America.
- The topic is “the cleaning of Boston Harbor” and the controlling idea is “the mayor's dedication.”
- Topic Sentence: There are many possible contributing factors to global warming.
- The topic is "contributing factors to global warming" and the controlling factor is "many reasons."
- Topic Sentence: Dogs make wonderful pets because they help you to live longer.
- The topic is "dogs make wonderful pets" and the controlling idea is "because they help you to live longer."
- Topic Sentence: Crime in poverty-stricken areas occurs as a result of a systemic discrimination.
- The topic is "crime in poverty stricken areas" and the controlling idea is "systemic discrimination."
- Topic Sentence: Alaska Young's death causes Pudge a lot of confusion and pain.
- The topic is "Alaska's death" and the controlling idea is "Pudge's confusion and pain."
- Topic Sentence: The female characters in these novels are mysterious.
- The topic is "the female characters in these novels" and the controlling idea is "are mysterious."
As you can see, the topic sentence provides a focus for the reader or listener. It tells what the paragraph is about. The controlling idea helps the audience understand what you are saying.