Topic sentences

Readers like to know why they're reading a particular passage as soon as possible. That's why topic sentences placed at the beginnings of paragraphs are a good habit. A topic sentence, as its name implies, states the paragraph's topic—it need not state the paragraph's particular argument about that topic. That means that questions can make good topic sentences.

　　Here, fairly at random, are several good topic sentences, all placed at the beginnings of paragraphs:

　　A popular audience for science, and for technology, blossomed in Europe and America in the 19th century. [Examples follow.]

　　The third and final area of Theban expansion was by sea in the Aegean. Here again the enemy was Athens. . . . [Detailed incidents follow.]

　　When we see a play, what is it that we see? [An answer follows.]

　　A special subcase of realist theories deals with

　　There's no iron rule that topic sentences must come at the beginning of paragraphs, but if you keep in mind that you're writing to be understood, you'll tend to put them there. That's what readers are used to, and that's what they find easiest to follow.