Once students can identify main (independent) clauses and main ideas, a simple graphic system will demonstrate whether their sentences are strong and unified. The student underlines the main clause of a sentence and circles the main idea. In a strong, unified sentence, the circle will sit on the line. If the circle does not sit on the line, the writer should consider revising the sentence so that its main idea is in its main clause. A variety of exercises (with answer keys) serve to explain and reinforce the concept, including one in which an identical set of sentences yields two paragraphs that make quite different points. (Author/NKA)