The Two Parts of a Topic Sentence
As noted earlier, a topic sentence has two essential parts: the topic and the controlling idea. The topic names the subject of the paragraph. The controlling idea limits or controls the topic to a specific area that you can discuss in the space of a single paragraph.
The reader immediately knows that this paragraph will discuss how easy it is to prepare convenience foods and perhaps will give some examples (canned soup, frozen dinners, and so on).
Convenience foods are easy to prepare.
The reader of this topic sentence expects to read about various ethnic foods popular in the United States: tacos, egg rolls, sushi, baklava, pizza, and so on.
Immigrants have contributed many delicious foods to U.S. cuisine.