“A means of picturing the structure of a sentence by placing the words on a horizontal line that is divided in two. The subject goes on the left side of the line, and the verb goes on the right side. Adjectives, adverbs, and other parts of speech are placed on separate lines under the subject or verb in such a way that illustrates how they modify those words. Many students find that diagramming sentences is like a game and that it helps them understand how sentences are constructed, how the different parts of speech function, and why it is important to be thoughtful in placing adjectives and adverbs in a sentence.”
Excerpted from: Ravitch, Diane. EdSpeak: A Glossary of Education Terms, Phrases, Buzzwords, and Jargon. Alexandria, VA: ASCD, 2007.