THIS SENTENCE IS NOT A RUN-ON SENTENCE:

The scandal broke after the teacher was charged with sexual harassment so the administration and the school board issued a statement to the media to dispel any rumors.

IT IS A COMPOUND SENTENCE IN WHICH THE COMMA IS INCORRECTLY OMITTED BEFORE THE COORDINATING CONJUNCTION so.

THIS SENTENCE IS A RUN-ON SENTENCE:

(sentence), (sentence)

Two sentences (independent clauses) that are not separated by any punctuation: I have always admired Wonder Woman for a long time she was my hero.

THIS SENTENCE IS NOT A COMMA SPLICE:

No one voted in the election, so the White House was empty for four years.

THE COMMA PRECEDING THE COORDINATING CONJUNCTION IS CORRECT.

THIS SENTENCE IS A COMMA SPLICE:

(sentence) ,(sentence)

Two sentences (independent clauses) separated only by a comma.

I never enjoyed reading comic books when I was a child, fantasy novels were always my favorite.

HOW TO CORRECT RUN-ONS AND COMMA SPLICES:

Use a semicolon or period to separate the two independent clauses/sentences:

I have always admired Wonder Woman; for a long time she was my hero.

I never enjoyed reading comic books when I was a child; fantasy novels were always my favorite.

RULES OF THUMB FOR RECOGNIZING FRAGMENTS

THIS SENTENCE IS NOT A FRAGMENT:

It is obsolete.

THIS GROUP OF WORDS HAS A SUBJECT, A VERB, AND A COMPLETED THOUGHT.

A FRAGMENT DOES NOT EXPRESS A COMPLETE THOUGHT:

B.B. King and Morgan Freeman know a lot about cotton fields. Both having grown up in the Mississippi Delta region. B.B. King from Indianola, Mississippi, and Morgan Freeman from Clarksdale, Mississippi.

The italicized portions are fragments.

A FRAGMENT MAY CONTAIN A SUBJECT AND A VERB BUT IS NOT AN INDEPENDENT THOUGHT:

I noticed several students leaving the dormitory. As I walked across the street past the trolley.

HOW TO CORRECT FRAGMENTS:

Add words or connect the fragment to the sentence from which it is disconnected.

B.B. King and Morgan Freeman know a lot about cotton fields, both having grown up in the Mississippi Delta region. B.B. King is from Indianola, Mississippi, and Morgan Freeman is from Clarksdale, Mississippi.

I noticed several students leaving the dormitory as I walked across the street past the trolley.