Relative Clauses and Commas


This lesson provides an introduction to the study of relative clauses - clauses that modify nouns. It is concerned with the punctuation of relative clauses and the ways in which intonation correlates with commas and can therefore help us accurately punctuate restrictive and nonrestrictive relative clauses.

Grade Level: 
Grades 6-8
Grades 9-12
Class Time Needed: 
2 hours
Lesson Plan: 

Commas' Connection to Spoken Language

One place that the spoken language has long been used to attempt to help with a rule of writing, specifically of comma usage, is the old adage that commas correlate with pauses. In fact, most commas - one estimate says 70% - do not correlate with pauses in spoken language. Commas, periods, and other marks of punctuation were first used as pause markers, as cues to the reader, or more specifically the orator, to take a breath. But that was some 1000 years ago. Today's punctuation is used to mark grammatical distinctions or to add clarity. (And some punctuation serves no purpose, but is simply used by convention; for example, separating a city and state name with a comma: Ferndale, Washington.)

A study by Danielwicz and Chafe (1985) on the punctuation practices of college freshmen suggests that what might appear to be punctuation errors in freshman compositions are attempts to capture prosodic features of speech in writing (cited in Baron, p. 191). These writers seem to be punctuating to mark the intonation they would have used in speaking. Consider this example from the writing of one of the students in the study:

One of these categories, that I can be classified in is that of an only child. (220)

Danielwicz and Chafe propose that the comma indicates an intonation boundary. Such errors are likely reinforced by the idea that commas always correlate with pauses. Paying attention not simply to pauses, but to intonation contours across speech can shed light on grammatical distinctions that we all possess. Also, when comma errors do occur, the error will undoubtedly be suggesting some kind of grammatical distinction, typically either a phrase or a clause. So rather than simply marking these as incorrect, the teacher and the students can try to determine what grammatical feature the writer was attempting to indicate with that particular use of punctuation.

We can use spoken language to help students with the conventions of written language in the identification of nonrestrictive (compared to restrictive) relative clauses, as well as appositives.

Relative clauses are clauses (so they include both a subject and a predicate) that modify a noun. They relate the information in the clause to the noun that precedes it, as in the following examples, where the relative clause is underlined:

The boy who you met at the airport is my cousin.
The place where I bought a book yesterday is on Broadway.
The woman who sang at the reception has a recording contract.

The relative clauses contain what is called a relative pronoun, such as who, where, that, which, that takes the place of the noun in the clause and refers to the noun outside of the clause. So in the example from above,

The boy who you met at the airport is my cousin.

who functions as the direct object in the relative clause and refers back to the boy. Relative clauses are a useful way of expanding shorter sentences into longer ones. However, in order to make use of this tool, students need to know what relative clauses are, what the various types are, how to use them appropriately in writing, and how to punctuate them.

Relative clauses fall into two classes, restrictive and nonrestrictive. All of the ones above are restrictive because they limit what the noun refers to. Though nonrestrictive relative clauses also provide information about a noun, they do not provide essential information that distinguishes the noun from others in a set. They are set off by commas in writing, and you can also detect comma intonation in a speaker's voice, distinguishing the two types.

Restrictive relative clause: The shoes which Sam bought yesterday were high tops.

Nonrestrictive relative clause: The shoes, which Sam bought yesterday, were high tops.

The interpretation of the nonrestrictive clause as non-essential, by-the-way information, rather than as information which distinguishes the shoes from other shoes, is what differentiates the two types. Native speakers have very good intuitions about this distinction, as evidenced by the different intonations used in the two sentence types.

Some evidence for the contrast between restrictive and nonrestrictive relative clauses can be seen when we look at modification of proper names. Nonrestrictive relative clauses may modify names, while restrictive cannot:

Sam, who bought new high tops, was at the game. (nonrestrictive)

??Sam who bought new high tops was at the game. (restrictive)

The non-restrictive relative clause, who bought new high tops, does not restrict the reference of the proper noun Sam; it is not information that distinguishes this Sam from other Sams, since presumably the name Sam is already picking out a unique individual. That Sam was at the game is simply incidental information, and is therefore set off by commas and a unique intonation.

There is a prescriptive rule that Microsoft Word and some style guides follow that concerns restrictive and nonrestrictive relative clauses; it suggests that one should use which in nonrestrictive relative clauses, but use that in restrictive relative clauses.

According to Word, here's how we should use which and that.

right: Chocolate chip cookies, which I love, are fun to make.
wrong: Chocolate chip cookies, that I love, are fun to make.

right: Chocolate chip cookies that have a lot of chips are the best.
wrong: Chocolate chip cookies which have a lot of chips are the best.

It may in fact sound odd to use that in a non-restrictive relative clause, as in this example: Chocolate chip cookies, that I love, are fun to make. However, using which in a restrictive clause is acceptable in many usage and style guides, including most British ones. And even for American copy editors, the prohibition against using which in restrictive relative clauses is a fairly recent one. Readers will find both which and that are common not only in edited writing today, but they have been in use for centuries by the best of writers. However, offering students the ability to identify the two clause types, using intonation distinctions as a clue, allows these writers to make their own informed decisions about writing conventions. Such attention to the spoken language, specifically listening to the natural patterns of intonation, will correctly pick out a nonrestrictive clause. Here again, it's empowering to know that our intuitions about our spoken language can help with conventions of writing.
Appositives are another type of modifier that is set off by both commas and corresponding intonation distinctions.

Jo, a friend of ours, likes to make flan.

Unlike relative clauses, appositive are not clauses, but just noun phrases. They give additional information about a noun, information that is not essential for our interpretation of the noun. Most students do not make writing errors with appositives, so these can be useful to illustrate how we accurately and unconsciously use intonation contours to set off this non-essential information here as well.