In Section 1.2, you learned about two different types of clauses (independent and dependent). In Section 1.3, you learned about the placement of clauses within compound, complex, and compound-complex sentences. Section 1.4 introduces you to another clause, the adjective clause. You can identify an adjective clause (also called a relative clause) by the relative pronoun or the relative adverb that appears at the beginning of the clause. Relative pronouns are who, whom, whose, that, or which, while relative adverbs include when, where, and why. Adjective clauses modify a word in a sentence, and they usually directly follow the words they modify. Sentences containing adjective clauses will be either complex or compound-complex.

Example:

• The children who eat breakfast do better in school.

The clause "who eat breakfast" is a group of words that modifies "children," telling us exactly which children do better in school. Notice that the clause begins with the relative pronoun who.

Essential vs. Nonessential Adjective Clauses

Some adjective clauses are essential to the meaning of a sentence, and they are called restrictive clauses. An essential adjective clause is important to a sentence's meaning. The sentence meaning changes if you delete the clause.

Example:

• All students who do their work should pass easily.

The essential clause "who do their work" is necessary to the sentence and cannot be removed without changing the meaning of the sentence to "All students should pass easily."

Notice that "who do their work" is also a dependent clause. It doesn't make sense on its own. It doesn't have commas around it, though, and that's because it's essential to the meaning of the sentence—it is not extra information.

Some adjective clauses are not essential to the meaning of a sentence, and they are called nonessential (or nonrestrictive) clauses. An adjective clause adds extra or nonessential meaning to a sentence. The sentence meaning does not change if you delete the clause.

Commas set off nonessential clauses, signaling to the reader that the clause contains extra information.

Example:

• Edgar Allan Poe, who wrote "The Raven," is a great American poet.

The nonrestrictive clause "who wrote 'The Raven,'" is not essential to the sentence and can be removed without changing the meaning of the sentence. You could write "Edgar Allan Poe is a great American poet," and it would not change the meaning of the sentence.

A Note about Punctuation and Grammar

Throughout Lesson One so far, you have read about how punctuation serves as a signal to the reader. It can help a reader understand the tone of a sentence (whether it's a question, statement, exclamation, or order), and it can help him or her break down and order the complex array of thoughts and ideas that a sentence can entail.

Punctuation is a lot like having manners. Sometimes it can feel like these rules are just things that someone made up to make life difficult, but rules can be quite handy for communicating well in society. Think of when you bump into a stranger accidentally. Your manners teach you to say you are sorry and perhaps ask the person if he or she is okay. Without a polite response, the other person might misunderstand you and think you are picking a fight. Manners give you a way to communicate and connect with the other person so you can reach an understanding.

Punctuation functions in the same way, as does good writing in general. As you practice writing throughout the course, think of proofreading, rewriting, and using correct grammar and punctuation as a way of politely helping your reader understand what you mean to say.

Assignment 1.4

Complete the Assignment 1.4 Quiz on adjective clauses.