I've noticed over the years that three aspects of punctuation are confusing for many ESL/EFL teachers.  These involve punctuation errors that are often considered important in the context of freshman composition courses--but really have wider implications for ESL/EFL students who need to be accurate writers. Thus, understanding comma splices, run-on sentences, and fragments is important for those of us who teach ESL/EFL to students who are likely do degree studies in a U.S. college or university. 

I'm going to give brief definitions and examples in this section of the lecture.  In addition, I will provide links to web-based activities that give you more information about these topics. 

A comma splice is the mis-use of a comma to make a compound sentence.  A compound sentence is made of two or more simple sentences that are combined to make a new sentence.  The new compound sentence should be created with particular types of connections. 

To make a compound sentence, you either

1. combine the two simple sentences by using a comma and one of the coordinating conjunctions

He loves sociology, and he plans to major in that disciplinary area.

He loves sociology; he plans to major in that disciplinary area.

*He loves sociology, he plans to major in that disciplinary area.

A common mistake by native speakers as well as ESL/EFL writers is to think that a conjunct (linking word, logical connector, conjunctive adverb) can be used with a comma to tie a sentence together.  Such a combination creates a comma splice because the adverb cannot take the place of a coordinating conjunction.

*He loves sociology, however, he plans to major in business administration.

The purpose of the FANBOYS mnemonic device is to help teachers and students remember the coordinating conjunctions.  There are just seven of them--definitely a closed class.  The most important of these are the words and, or, and but.  The others have more limited use. 
 
 
 

Now let's take a look at the punctuation error that is called a run-on sentence.  Years ago, I heard an ESL teacher explain run-on sentences to her class.  She had mistakenly thought that run-on was the same as "to talk too much"--to "run-on at the mouth" in the rather unpleasant expression.  While I know that some writers do go on and on and on that's not the point of run-on sentence. 

A run-on sentence is a compound sentence that has been incorrectly punctuated.  There are two types of run-on sentences:

1.  One type involves writing that has sentence after sentence presented without end punctuation--without a period at the end of one sentence or a capital letter at the beginning of the next.  Sentences just run together. This type of writing tends to be the product of a new writer who hasn't yet learned to separate speaking from writing.

He loves sociology as a discipline however he plans to major in anthropology to the dismay of his mother she prefers geography.

He loves sociology and he plans to major in that disciplinary area.

While comma splices can seem like something that only we English majors can get very excited about, run-on sentences and sentence fragments are more important areas for all writing teachers to learn about and to find ways to help students move beyond.  Both run-on sentences (of the first type) and sentence fragments generally indicate that a student has not yet progressed to an advanced level as a writer of English prose.  Thus, they can sometimes be developmental stages that learners go through.  Of course, sometimes they are just signs of writers in a hurry who haven't taken the time to edit their products carefully enough.  Let's take a look at a definition and some examples of fragment and then look at a sample of student writing that shows the results of fragments for readers.

A fragment is a piece of a sentence used as if it were a complete sentence.  Look at the following example to see a typical fragment:

He loves sociology.  Because he is fascinated with understanding how people behave in social groups.

There are times when fragments are "legal."  We use them in headings, for example, and in lists.  And we sometimes use them in formal written English when we mimic the question-answer style of conversational English.  Look at this sample from the newspaper in Fort Collins, Colorado.  Here the writer asks a question and then answers it with words rather than complete sentences.  (The answer, by the way, turns out to be house cats.)
 
 

In sum, when fragments are used deliberately by a writer for some dramatic effect--that's ok.  We are looking for fragments created by less experienced writers who still are not fully in command of English written sentence structures.  Look at the following sample of student writing to see how fragments look in real authentic student produced English.
 

As you can see from what she says about herself, the writer is an international student who is native speaker of English.  Native speakers and NNS speakers can have trouble with learning to separate talking from writing.  You will see similar patterns in the writing of ESL/EFL students, especially those who have better spoken English than written English.  I suggest that you copy this sample (highlight it, copy it, and then paste it into your word processing system) and look through to find the various fragments.  Often they are adverbial clauses that have been punctuated as independent sentences rather than attached to the independent clause to which they are related.
 
 

Please send me your questions and comments at patbyrd@comcast.net.  Thanks.