Start with a sentence that includes a direct object such as this: I kicked the red ball over the fence. Write the sentence on the piece of paper. Do you know which word is the subject? It is the noun or pronoun that does the action of the verb. Here, the subject is "I". Verbs are words of action or being. Here, the verb is "kicked". The direct object is the noun or pronoun that receives the action of the verb. Here the way to find the direct object is to answer the question: "What did I kick?" The direct object of this sentence is "ball".
Draw a horizontal line to start your sentence diagram. Place a small perpendicular line that extends through the horizontal line near the left edge. Place the subject, "I" on the line to the left of the perpendicular divider. Label the subject above the diagram as in the illustration.
Write the verb, "kicked" on the diagram to the right of the perpendicular divider. Label it above the diagram as the verb.
Draw a second perpendicular line to the right of the verb that touches but does not go through the horizontal line. Write the direct object, "ball", to the right of this divider. Label it above the diagram as the direct object.
Notice that the direct object has several modifiers. "The" shows that the sentence refers to one specific ball and not just any ball. "Red" further describes the color of the ball. "Over the fence" is a prepositional phrase that tells where the ball is located. All of these are adjectival modifiers so they hang on lines underneath the direct object they qualify or describe. Since "over the fence" is a phrase, you will see that it works a little bit differently. The preposition, "over" is on the diagonal line; the noun, "fence" is on the horizontal line, and the definite article, "the" acts like an adjective for the noun, "fence."