Kinneavy's theory of discourse and Mathes' concept of contextual editing can be effectively applied to teaching classification in technical writing. My procedure, in the nine steps described here, provides students with an understanding of classification as an analytical and generative tool. Its usefulness in analysis is discovered through a structural study of Mumford's “Machines, Utilities, and ‘The Machine‘”; an awareness of Mumford's classificatory structure helps students understand his essay. Students see for themselves, by organizing facts into paragraphs, the generative power of contextual editing applied to classification; the same kind of structuring Mumford uses can be used in their own writing. This generative application simulates the research-to-writing process and dramatically increases the coherence and clarity of much student writing.