When we read a paragraph, there is usually one central idea or thought expressed.  The topic sentence answers this question...What is this essay about?

A topic sentence has several important functions: it directs the order of the sentences and it advises the reader of the subject to be discussed and how the paragraphs will discuss it.

Choose a prompt and develop an topic sentence for it.  Use descriptive verbs, adjectives and adverbs.  Then follow the structure guidelines to write the essay.