Punctuation marks: the comma and the period, fragments, runon sentences

1. Writing
Punctuation:
The Period and the Comma

2. The Period and the Comma The comma and period
are distinguished with
reference to their
functions:
• The comma is used to
connect elements
within a sentence.
• The period is used to
end sentences.
In other words, periods
act as terminators and
commas as joiners.

3. Punctuation
Errors in
Writing
Two of the most common punctuation mistakes are
comma splices and fused sentences.
They occur when independent clauses are
improperly joined to form a compound sentence.
To properly combine clauses into compound
sentences, the end of each independent clause
must be signaled by appropriate punctuation, such
as a comma followed by a coordinating conjunction
or a period at the end of the sentence.

4. What is an
independent
clause?
An independent clause is a group of
words that contains a subject and a verb.
It expresses a complete thought. An
independent clause is a sentence on its
own.
• No matter how you look at it
• He knew what was going to happen
• Supposing that she really wanted to go
• What you should do is clear.
IC
X
IC
X

5. Comma Splices
Comma splices occur when a comma is used by itself (without a
coordinating conjunction) to join two independent sentences.
Roberto Pérez belongs to The Slow Movement, he enjoys doing things
slowly.
The need for speed is the worst thing in people’s lives, it destroys our health.

6. Comma Splices
You can correct this punctuation error either by adding a coordinating
conjunction or by separating the two independent sentences using a
period and a capital letter.
Roberto Pérez belongs to The Slow Movement. He enjoys doing things
slowly.
The need for speed is the worst thing in people’s lives, for it destroys
our health.

7. Fused Sentences
A fused sentence occurs when two independent clauses are joined
without any punctuation.
missing punctuation
A pistachio tree takes a minimum of seven years to produce nuts
they produce the most nuts after about 20 years.

8. Fused Sentences
This type of error can also be fixed either by separating the two
independent sentences using a period and a capital letter or by using a
comma and coordinating conjunction (if there is a relation between the two
clauses).
A pistachio tree takes a minimum of seven years to produce nuts, and they
produce the most nuts after about 20 years.
A pistachio tree takes a minimum of seven years to produce nuts. They
produce the most nuts after about 20 years.

9. Let’s Practice
1. He enjoys walking through the country, he often goes
backpacking on his vacations.
2. He often watched TV she preferred to read instead.
3. They weren't dangerous criminals they were detectives in
disguise.
4. I didn't know which job I wanted I was too confused to
decide.

10. Let’s Practice-Key
1. He enjoys walking through the country, so he often goes
backpacking on his vacations.
2. He often watched TV, but she preferred to read instead.
He often watched TV. She preferred to read instead.
3. They weren't dangerous criminals. They were detectives in disguise.
4. I didn't know which job I wanted, for I was too confused to decide.
I didn't know which job I wanted. I was too confused to decide.

11. Fragments
They are incomplete sentences.
Usually, they are pieces of sentences
that have become disconnected
from the main clause. One of the
easiest ways to correct them is to
remove the period between the
fragment and the main clause. Other
kinds of punctuation may be needed
for the newly combined sentence.

12. Some
examples
• Fragment: Purdue offers many majors in
engineering. Such as electrical, chemical, and
industrial engineering.
Possible Revision: Purdue offers many majors in
engineering, such as electrical, chemical, and
industrial engineering.
• Fragment: I need to find a new
roommate. Because the one I have now isn't
working out too well.
Possible Revision: I need to find a new
roommate because the one I have now isn't working
out too well.

13. Some
examples
No main verb
• Fragment: A story with deep thoughts
and emotions.
Possible Revisions:
• Direct object: She told a story with
deep thoughts and emotions.
• Fragment: Toys of all kinds thrown
everywhere.
Possible Revisions:
• Complete verb: Toys of all
kinds were thrown everywhere.
• Direct object: Teachers found toys of all
kinds thrown everywhere.

14. Some
examples
No Subject
• Fragment: With the ultimate effect of all
advertising is to sell the product.
Possible Revisions:
• Remove preposition: The ultimate effect of all
advertising is to sell the product.
• Fragment: By paying too much attention
to polls can make a political leader
unwilling to propose innovative policies.
Possible Revisions:
• Remove preposition: Paying too much
attention to polls can make a political leader
unwilling to propose innovative policies.

15. Information taken and adapted from:
Difference between Comma and Period. (2021).
http://www.differencebetween.info/difference-between-comma-and-period
Henry, D. J. (2014). Writing for Life. Paragraphs and Essays. Pearson Education.
Purdue University.(2021). Purdue Online Writing Lab.
https://owl.purdue.edu/owl/general_writing/mechanics/sentence_fragments.html
The Punctuation Guide. (n.d.).
https://www.thepunctuationguide.com/comma.html