Final answer:
The central idea of a non-fiction article is typically found in the introduction, which includes the thesis statement outlining the main theme or claim.
Step-by-step explanation:
The central idea in a non-fiction article is most commonly introduced and summarized in the introduction of the piece. This introductory section often sparks the reader's interest and leads seamlessly into a definitive statement of the main theme or claim of the article. The introduction aims to present the thesis statement, a clear and concise declaration of the article's central point. Though key points are summarized in the introductory segment, they are then more fully developed within the body paragraphs, which are built around topic sentences that support the thesis. Moreover, these body paragraphs provide evidence and analysis that reinforce the central idea. Nonetheless, the introduction typically contains the initial presentation of the central idea, and its quality can range from lacking a clear thesis to containing a clear, intriguing thesis as outlined in various examples.