2. What is a Comma?
• A comma is a
punctuation mark
that indicates a
pause is needed in a
sentence.
• Commas help to
clarify meaning for
the reader.
3. Clauses and Phrases
• A clause is a group of words that contains
both a subject and a verb that
complement each other.
• A phrase is a group of words that does
not contain a subject or a verb that
complement each other.
4. Sentence Structure:
Independent Clause
• A complete sentence has two
components, a subject and a verb.
• The subject and verb must form a
complete thought to be considered an
independent clause.
The couple dances.
subject (S) verb (v)
5. Sentence Structure:
Compound Sentence
• A sentence that contains
two independent clauses
joined by a coordinating
conjunction is called a
compound sentence.
• A conjunction joins words,
phrases, and clauses
together in a sentence.
• Conjunctions
– for
– and
– nor
– but
– or
– yet
– so
F A N B O Y S
6. Sentence Structure:
Compound Sentences
• The comma in a compound sentence
is placed before the coordinating
conjunction.
S V Conj. S V
Andy built a snowman, and Jeff played
with his dog.
8. Sentence Structure:
Dependent Clause
• A dependent clause
contains a subject
and verb, but the
clause cannot
stand
independently.
• Dependent clauses
can often be
identified by the
use of dependent
clause markers.
• Some dependent clause markers:
because
since
when
while
until
if
as
though
although
unless
after
before
once
whether
9. Sentence Structure:
Dependent Phrases & Clauses
• Dependent phrases and clauses help to
clarify and add detail to an independent
clause.
• Dependent clauses may appear at the
beginning, middle, or end of a sentence.
10. Sentence Structure:
Introductory Clause
• When a dependent clause is placed at
the beginning of a sentence, place a
comma between the independent
clause and the dependent clause.
Dep. clause S V
Before he took the test, Dan struggled with
Conj. S V
his homework, so his father helped him.
11. Introductory Clause
• Where would you place the comma in the
following example?
S V
Because it was raining we decided to go
to the movies.
12. Introductory Clause
• Where would you place the comma in the
following example?
Introductory clause S V
Because it was raining, we decided to go
to the movies.
13. Dependent Clause
When a dependent clause is
located after an independent clause,
Do not place a comma between the two.
S V
We decided to go to the movies because
we were bored.
14. Sentence Structure: Essential
Phrases and Clauses
• An essential clause or phrase is used to
modify a noun.
• It also adds information that is critical to
the meaning of the sentence.
• Essential clauses are NOT set off by
commas.
S essential phrase V
The people who work in my office are loud.
15. Sentence Structure: Essential
Phrases and Clauses
• The word “that” is almost always an indicator of
an essential phrase or clause.
S essential V
The tiramisu that I had at Joe’s was great.
16. Sentence Structure: Nonessential
Phrases & Clauses
• A nonessential phrase or clause adds
extra information to a sentence.
• This information can be eliminated from
the sentence without jeopardizing the
meaning of the sentence.
• Always place commas around
nonessential phrases and clauses.
17. Sentence Structure: Nonessential
Phrases & Clauses
• Even without the phrase the sentence still
makes sense: My brother plans to throw
a party.
S non-essential V
My brother, who lives across town, plans
to throw a party.
18. Sentence Structure: Nonessential
Phrases & Clauses
• Use commas to set off additional
information.
S V
Steve said that he would propose to me on
non-essential
Valentine’s Day, which is my favorite holiday.
19. Comma Practice
• Would you place commas in the following
sentences? If so, where?
I am planning a trip to Paris which is one of the
greatest cities in the world.
The place that I would most like to see is the
Eiffel Tower.
Pierre, who is one of my business contacts, will
meet me at the airport.
20. Sentence Structure: Commas
in a Series
• Place commas in a sentence to divide
items in a list.
• The commas will help the reader to avoid
confusion.
• The comma before the conjunction is
generally required, but it can be omitted if
there is no possibility of confusion.
21. Sentence Structure: Commas
in a Series
Consider the difference in the following:
Last month, Alex dated Mary Ann Lee and Kim.
Last month, Alex dated Mary, Ann, Lee, and Kim.
Last month, Alex dated Mary Ann, Lee, and Kim.
How many women did Alex date?
22. Sentence Structure: Commas
in a Series
• Commas should be placed in series of
words, phrases, or clauses.
• Place commas in the following sentences:
Martina brushed her hair put on her pajamas,
and went to bed.
She fell asleep and dreamed that she was a
princess she kissed a frog and she rescued her
prince.
23. Commas with Adjectives
• Use commas to separate adjectives that
provide an equal description of a noun.
The Test:
Can you put “and” between the
adjectives?
Can they be described in reverse order?
If so, use a comma.
big blue house | three hungry kittens | a cranky, bald man
24. A Common Error: The Comma
Splice
• A comma splice is an error in which two
independent clauses are joined by a
comma.
S V
Dan struggled with his homework, his
S V
father helped him.
25. To Correct a Comma Splice
• Insert a conjunction between the two
independent clauses.
• Start a new sentence.
• Insert a semi-colon between the two
independent clauses (only in cases
where the independent clauses are
closely related in topic).
26. To Correct a Comma Splice
S V Conj.
Dan struggled with his homework, so his
S V
father helped him.
27. To Correct a Comma Splice
S V
Dan struggled with his homework. His
S V
father helped him.
28. To Correct a Comma Splice
S V
Dan struggled with his homework; his
S V
father helped him.
29. Comma Splice Practice
• How would you correct the following?
This semester I am taking calculus physics and
economics.
Calculus is my best subject, I am certain I will get an A.
Although I am very busy, I still find time to have fun.
Last weekend my brother visited me and we went to a
football game a party and a rock concert.
30. Additional Help
• Purdue University Writing Lab,
Heavilon 226
• Check our web site:
http://owl.english.purdue.edu
• Email brief questions:
http://owl.english.purdue.edu/writinglab/email/owlmail
Key Concepts: The facilitator may choose to invite the audience to respond to the title question and allow participants to discuss the function of the comma. Many writers become frustrated with comma usage because they are unsure of where to place them in their sentences. This presentation is designed to demystify the placement and usage of commas. The facilitator may stress to participants that commas should not be ignored in writing; they are often needed to clarify meaning within a sentence and can help to avoid confusion. Click mouse after title question to reveal each response.
Key Concepts: This slide articulates the basic differences between a clause and a phrase . The facilitator may stress the importance of understanding these definitions for understanding comma placement.
Key Concepts: This slide explains the structure of an independent clause , the primary building block for the development of any sentence. An independent clause requires a subject and a verb that can stand as a complete thought. Sentences can be very short, as the one detailed in the slide. The facilitator may ask the audience to identify the subject and verb in the example.
Key Concepts: This slide explains the structure of a compound sentence and the role of a conjunction. An easy method for remembering the seven coordinating conjunctions is the acronym “fan boys.”
Example: This slide exemplifies the location of a comma in a compound sentence, before the coordinating conjunction. The facilitator may ask participants to identify the subjects, verbs, and conjunction in the example.
Example: This slide provides participants with an opportunity to locate the correct position for the comma within the sample sentence. The facilitator may also invite students to identify the subjects, verbs, and conjunction in the sentence.
Key Concepts: This slide explains the definition of a dependent clause . The dependent clause markers can help writers identify clauses that cannot stand alone within a sentence.
Key Concepts: This slide further clarifies the role of dependent phrases and clauses within a sentence.
Key Concepts: An introductory clause is a dependent clause located at the beginning of a sentence. After an introductory clause, a comma is needed to distinguish it from the independent clause. Activity: The facilitator may choose to ask students to identify the independent and dependent clauses, the subjects, the verbs, and the dependent clause marker in the sample sentence.
Activity: This interactive slide invites participants to place commas after the introductory clauses in each sentence. Again, the facilitator may ask students to identify the parts of speech in the example.
Activity: When a dependent clause follows an independent clause, commas are not used. Facilitators may choose to ask students to identify the parts of speech in the example.
Key Concepts: This slide leads off a section about essential and non-essential phrases and clauses . Essential phrases and clauses—elements that add critical information to the meaning of a sentence—do not have commas placed around them. For the slide example: Without the essential phrase, this sentence does not make complete sense : The people are loud! While the sentence is grammatically correct, we don ’t know about the people being discussed.
Key Concept: The word “that” almost always indicates an essential phrase or clause.
Key Concepts: This slide illustrates the difference between essential and nonessential elements. While commas should not be placed around essential phrases and clauses, they should be placed around nonessential phrases and clauses.
Example: Nonessential phrases and clauses can be removed from sentences without jeopardizing the overall meaning of a sentence. In this example, “who lives across town” is superfluous information; it is not critical to the main message of the sentence—the woman’s brother will throw a party for her.
Example: This slide provides another example illustrating the placement of a nonessential phrase within a sentence. At the end of a sentence, the nonessential element should have a comma placed before it and a period after it. The facilitator may wish to stress that “which” often, but not always, indicates a nonessential phrase or clause.
Activity: These examples allow participants an opportunity to test their comma skills. The first example needs a comma after “Paris” to set off the nonessential phrase. The second example requires no comma. The phrase “that I would most like to see” is essential to the meaning of the sentence. The sentence will not make sense without this essential phrase. The third example requires two commas, both before and after the nonessential phrase “who is one of my business contacts.” The main message of this sentence—that Pierre will meet this person at the airport—is clear without knowing the additional information about his identity.
Key Concept: Commas should be placed between each element within a list. This placement can help the reader to avoid confusion.
Activity: These examples illustrate the importance of comma placement within a list. The facilitator may ask students to answer the question “How many women did Alex date?” in accordance with each example—two women in the first, four in the second, and three in the third.
Activity: The facilitator may stress to participants that a series includes a list of words, but it can also include a list of phrases or clauses. This exercise allows participants to determine when the commas should be placed in each sentence.
Key Concepts: Students often find comma placement between adjectives to be tricky. The key is to determine if the adjectives are equal—meaning that they modify the noun in the same capacity. Adjectives of size and quantity are generally considered to be unequal to adjectives of character or quality. Placing “and” between adjectives or reversing the order of adjectives are good tests to determine if a comma is needed.
Key Concepts: One of the most prevalent comma errors is the comma splice—the placement of a comma between two independent clauses.
Key Concepts: This slide enumerates several methods for correcting comma splices. The examples listed in the next three slides are corrections of the comma splices in the previous slide.
Add a coordinating conjunction.
Start a new sentence.
Insert a semi-colon between the two independent clauses (only in cases where the independent clauses are closely related in topic).
Activity: This slide invites participants to again test their comma skills. The first example requires commas between each element within the list. The second example contains a comma splice. The sentence may be corrected by the addition of a conjunction after the comma, turning the comma splice into a compound sentence. This example may also be corrected by separating the two clauses into two separate sentences, or by changing the comma to a semi-colon. The third example requires a comma after the introductory clause. The facilitator may wish to note that “although” is a dependent clause marker. The fourth example, a compound sentence, requires a comma before the conjunction. Commas are also needed after each element in the list.
Rationale: As the presentation concludes, the facilitator can remind students that they can come to the Writing Lab for extra help with comma usage. Click mouse after the title question. For additional assistance with comma usage, see: Harris, Muriel. Prentice Hall Reference Guide to Grammar and Usage . 4 th ed. Upper Saddle River, NJ: Prentice Hall, 2000.