Be sure you present your parts in a logical order. Be sure your classifications are consistent with your purpose. Be sure you include all items that belong in your classification. Be sure you present your categories in a logical order. Don't overlap categories.
Introduction is at least one paragraph and contains a clear thesis statement.
Introdution introduces the main points that will be expanded upon in the supporting paragraphs. Introduction invites the reader in. Supporting paragraphs must each begin with a clear, underlined topic sentence. All other sentences in that paragraph must be relevant to the topic sentence. The paragraphs are well developed.