To teach students how to write in a contemporary style, a secondary-school English teacher must be able to describe adequately the kind of writing he expects. Since many modern writers frequently ignore the guidelines proffered in traditional writing handbooks, the "new rhetoric"--a descriptive approach to composition that substitutes objective, verifiable data for traditional rules--can be of immediate practical value to the teacher in describing contemporary writing models. An analysis of a paragraph from Ray Bradbury's "A Sound of Thunder," based on such quantitative descriptions as frequency counts of words, sentence length, modal varieties and repetitions, and grammatical and rhetorical constructs, indicates that Bradbury almost entirely ignores most traditional advice and achieves his effect through a "cumulative" layering that builds the paragraph sentence-by-sentence in a manner similar to the phrase-by-phrase construction of a sentence. By leading students through such an analysis of contemporary writers and then devising suitable exercises based on the principles discovered in the models, the teacher can clearly and exactly guide his young writers in the process of composition. (LH)