How to Diagram a Sentence: A Step-by-Step Guide

Sentence diagramming is visually arranging the components of sentence structure and different parts of speech in order to map out the best way to construct your phrasing. Diagramming uses straight lines and slanted lines to help you separate, analyze, and organize the function of your words in a way that delivers the clearest picture.

The purpose of diagramming sentences is to ensure your syntax is clear and easy to understand. Here is how diagramming can help you improve your writing:

• To highlight proper grammar: Sentence diagramming helps you ensure your writing adheres to the fundamental sentence structures of the English language. Both basic sentences and complex sentences require a subject and verb, and a diagrammed sentence can show how best to combine those elements in order to create a clear and grammatically correct sentence.
• To identify fragments: Diagramming helps identify fragments or subordinate clauses—also known as dependent clauses, which contain a subject and a verb but doesn’t express a complete thought. When you diagram, you ensure that you have all parts of a sentence present.
• To establish word order: A sentence diagram displays the proper order for subject complements, like predicate adjectives (which describe the subject) and their linking verbs (are, is, were) to ensure your writing flows smoothly.
• To place appositives: Sentence diagramming aids writers in figuring out when and where to implement appositives (noun phrases that rename another noun), as well as a variety of other sentence components, showing how they all connect and work together to communicate language efficiently.

The kind of sentence you’re building will determine how you diagram. Below are some ways you can diagram sentences and build on them to create better writing:

1. 1. Start with two lines. Draw a horizontal line cut in the center by a vertical line. The left side of the vertical line represents the subject of the sentence (the person or thing performing the verb), and the right is the predicate (the words that modify the subject and usually introduce an action).
2. 2. Add the subject and predicate. For a basic sentence, start with a simple subject and a verb phrase. This becomes your independent clause, which is a sentence that can stand on its own. If you use “the man” as the subject and “waved” as the predicate, “The man waved” would be the resulting diagrammed sentence.
3. 3. Build on your independent clause. Some sentences involve a direct object—the “what” or the “whom” of the sentence—which is the recipient of the transitive verb (also known as the action verb). If you’re including a direct object, draw another vertical line to the right of the predicate—this will be where the direct object goes. An example of a complete sentence with a direct object is, “The darkness scared the baby.”
4. 4. Add modifiers. Sometimes words need additional modifiers in order to create a more specific picture—this is where indirect objects come into play. Direct objects receive the verb’s action, and indirect objects, which generally have a preposition with them, receive the direct object. Beneath your verb, draw a diagonal line connecting it with the indirect object. “The teachers gave their students (indirect object) a passing grade (direct object).” When diagrammed correctly, each element of your sentence is parsed in a visual way that ensures each piece is functioning as it should.
5. 5. Make your sentence more complex. If you want to write longer sentences, join two independent clauses with a comma or conjunction, and mark them with a dotted line on your diagram. Ensure that each sentence is its own complete thought and can stand on its own before combining it with another to make a compound sentence.

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