Learn How to Diagram a Sentence

A sentence is the largest independent unit of grammar: It begins with a capital letter and ends with a period, question mark, or exclamation point. In English grammar, sentence structure is the arrangement of words, phrases, and clauses. The grammatical meaning of a sentence is dependent on this structural organization, which is also called syntax or syntactic structure.

You can learn how a sentence works, and understand its structure, by diagramming it or breaking it down to its component parts.

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Subject and Verb

The most basic sentence contains a subject and a verb. To begin diagramming a sentence, draw a baseline beneath the subject and the verb and then separate the two with a vertical line that extends through the baseline. The subject of a sentence tells you what it's about. The verb is an action word: It tells you what the subject is doing. At its most basic, a sentence can be composed of just a subject and a verb, as in "Birds Fly."

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Direct Object and Predicate Adjective

The predicate of a sentence is the part that states something about the subject. The verb is the main part of the predicate, but it may be followed by modifiers, which can be in the form of single words or groups of words called clauses.

For example, take the sentence: Students read books. In this sentence, the predicate contains the noun "books," which is the direct object of the verb "read." The verb "read" is a transitive verb or a verb that requires a receiver of the action. To diagram, a direct object, draw a vertical line that stands on the base.

Now consider the sentence: Teachers are happy. This sentence contains a predicate adjective (happy). A predicate adjective always follows a linking verb.

A linking verb can also precede a predicate nominative, which describes or renames the subject, as in the following sentence: My teacher is Ms. Thompson. "Ms. Thompson" renames the subject "teacher." To diagram a predicate adjective or nominative, draw a diagonal line that rests on the base.

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Clause as Direct Object

Consider the sentence: I heard you were leaving. In this sentence, a noun clause serves as a direct object. It is diagrammed like a word, with a vertical line preceding it, but it stands on a second, raised, baseline. Treat the clause as a sentence by separating the noun from the verb.

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Two Direct Objects

Don't be thrown off by two or more direct objects, as in the sentence: Students read books and articles. If a predicate contains a compound object, simply treat it the same as a sentence with a one-word direct object. Give each object—in this case, "books" and "articles"—a separate baseline.

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Adjectives and Adverbs That Modify

Individual words can have modifiers, as in the sentence: Students read books quietly. In this sentence, the adverb "quietly" modifies the verb "read." Now take the sentence: Teachers are effective leaders. In this sentence, the adjective "effective" modifies the plural noun "leaders." When diagramming a sentence, place adjectives and adverbs on a diagonal line below the word they modify.

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More Modifiers

A sentence can have many modifiers, such as in: Effective teachers are often good listeners. In this sentence, the subject, direct object and verb may all have modifiers. When diagramming the sentence, place the modifiers—effective, often, and good—on diagonal lines below the words they modify.

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Clause as Predicate Nominative

A noun clause can serve as a predicate nominative, as in this sentence: The fact is you are not ready. Note that the phrase "you are not ready" renames "the fact."

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Indirect Object and Understood You

Consider the sentence: Give the man your money. This sentence contains a direct object (money) and an indirect object (man). When diagramming a sentence with an indirect object, place the indirect object—"man" in this case—on a line parallel to the base. The subject of this imperative sentence is an understood "You."

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Complex Sentence

A complex sentence has at least one principal (or main) clause with a main idea and at least one dependent clause. Take the sentence: I jumped when he popped the balloon. In this sentence, "I jumped" is the main clause. It could stand alone as a sentence. By contrast, the dependent clause "When he popped the balloon" cannot stand alone. The clauses are connected with a dotted line when you diagram a sentence.

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Appositives

The term apposition means "next to." In a sentence, an appositive is a word or phrase that follows and renames another word. In the sentence "Eve, my cat, ate her food," the phrase "my cat" is the appositive for "Eve." In this sentence diagram, the appositive sits next to the word it renames in parentheses.