Every sentence must contain two parts: a subject and a verb. All the other words in a sentence merely describe, limit or modify the subject or the verb of the sentence. A technique known as diagramming is used to visualize the pattern of a sentence. Diagramming involves discovering and displaying the skeleton of a sentence.
I. THE BASIC PATTERN: Subjects and Verbs
The standard pattern in English is for the subject or noun of the sentence to be listed first, followed by the verb or action word of the sentence. The basic pattern for diagramming a sentence involves writing the subject on a horizontal line followed by the verb with a vertical line separating them.
Thus, sentences such as "Maria cooked" and "Maria is cooking" would be diagrammed as:
As we shall soon see all the other words in a sentence revolve around the two essential parts of every sentence --the subject and the verb.
II. ADDING TO THE BASIC PATTERN
A. Diagramming Adjectives and Adverbs.
The words which modify or describe the subject and verb of the sentence are diagrammed by placing them on slanted lines beneath the words which they modify. Thus, adjectives are placed beneath the subject and adverbs are placed beneath the verb according to the following pattern:
The three sentences below would be diagrammed as on the right with the adjectives being placed beneath the subject (noun) and the adverbs beneath the verb, which they modify:
The boy ran. 
The boy ran fast. 
The tall boy ran fast. 
Practice Set #l--Diagram the following sentences looking carefully for the subject and verb in each sentence and any adjectives or adverbs modifying them. Get the answer key.
1. Diana sang.
2. Maria ran slowly.
3. Gary spoke softly.
4. The small child fell down.
5. Mark is studying.
6. Juan is very quiet.
B. Diagramming the Direct and Indirect Objects of the Verb.
The direct object of a sentence is the noun, which names whatever receives the action of the verb. The direct object is placed on the primary horizontal line to the right of the verb and separated from the verb by a vertical line, which does not descend below the line according to the following pattern.
Thus, a sentence such as "Maria cooked rice" would be diagrammed as:
The subject of the sentence identifies who did something (Maria), the verb identifies what action was perfofll1ed (cooked), and the direct object identifies what was cooked (rice).
The indirect object names the person or thing to whom or for whom something is done. An indirect object is diagrammed by placing it on a new horizontal line beneath the verb and connecting it to the verb by a slanting vertical line in the following fashion:
Thus, a sentence such as "Maria gave Joe the rice" would be diagrammed as:
The subject of the sentence identifies who did something {Maria), the verb identifies what action was performed (gave), the direct object identifies what was given (rice), and the indirect object identifies to whom (Joe) the rice was given.
Practice Set #2 --Diagram each of the following sentences looking carefully for the six sentence parts already discussed. Get the answer key.
1. Scott plays soccer.
2. Carlos kicked the can.
3. Sonia walked home.
4. Carla gave David the book.
5. Joe gave Maria the notebook.
6. Rosie dropped the dish.
C. Diagramming Prepositional Phrases.
Prepositional phrases are frequently used to modify the subjects and verbs of sentences. A prepositional phrase must contain (a) a preposition, (b) the object of the preposition, and (c) any modifiers of the object. To diagram a prepositional phrase, the preposition is placed on a slanted line beneath the subject or verb which the phrase modifies, the object of the preposition is placed on a horizontal line below the primary horizontal, and any modifiers of the object are placed on slanted lines beneath the object of the preposition. The general pattern is as follows:
Thus, a sentence such as "Helga threw the ball to Boris" would be diagrammed as follows:
Note --You should have noticed that only verbs and nouns (whether as subjects, direct objects, indirect objects or objects of a preposition) are placed on the horizontal lines. All other words, whether adjectives. adverbs, or prepositions are placed on slanted vertical lines beneath the noun or verb which they modify.
Practice Set #3 --Diagram each of the following sentences. Get the answer key.
I. Roberto walked to the store.
2. Alex was thrown from the raft.
3. The large airplane fell to the ground.
4. Cathy hid behind the tree.
5. The boy in the blue shirt jumped over the creek.
6. We invited Heta to our house.
7. Mike went to the soccer game with Frank.
Developed by Monica Orozco
Student Learning Assistance Center ( SLAC )
San Antonio College, 1995