Diagramming sentences is a way of visually representing the parts of speech. The basic sentence pattern is a straight line that includes a space for the subject, verb and complements. Modifiers, such as adjectives, adverbs and prepositional phrases, connect to the main line on diagonal lines.

Placing Subjects, Verbs, Adjectives and Adverbs

Start by drawing a horizontal line for the main sentence line. Draw a vertical line that crosses the horizontal line halfway across. In the sentence, “The dog runs,” place the subject, dog, on the left side of the vertical line and the verb, runs, on the right side. The is the article adjective. Place the word on a slanted line under dog because it modifies dog. If the sentence is “The skinny dog runs quickly,” add another diagonal line under dog for skinny, an adjective, and a diagonal line under runs for quickly, an adverb that modifies runs.

Placing Prepositional Phrases and Direct Objects

Prepositional phrases go under the part of speech that they modify. For example for “The dog runs to the store,” “to the store” is the prepositional phrase, and it modifies runs. Draw a line under runs that first slants and then goes straight so that it becomes parallel with the main line. Write the preposition, to, on the slant and the object of preposition, store, on the straight line. Next, add another slanted line under store for the word "the." If the sentence is “The dog chews the ball,” chews is the verb and the direct object is ball. Draw a vertical line after the verb that touches, but does not cross, the main line. Place the direct object after this line to separate it from the verb.