Recognizing run-on sentences is hard for some students. I’ve found one trick that helps students find many of them: Look for a subject pronoun in the middle of a sentence. That pronoun could be a clue that the sentence is a run-on.
The most common pronoun that confuses students is “it.” And if “it” is followed by a linking verb, that is even more confusing. Here are a few run-ons using “it”:
Run-on: I like that video game it is fun.
Run-on: His arm was long it went into my personal space.
Run-on: The car kept accelerating it reached fifty miles per hour.
Other subject pronouns within run-on sentences also confuse students:
Run-on: Jack let me out of the car I breathed a sigh of relief.
Run-on: Quadralaterals have four sides they are not always the same lengths.
Run-on: Lincoln was assassinated he died the next day.
Of course, not all run-on sentences contain a pronoun to start the second clause. But many do. Students having trouble recognizing run-ons should be trained to look for subject pronouns in the middle of sentences.
But that’s only half the problem. How does a student fix such a sentence? One way is to add a comma and the word “and.” Reread the sentence. If it sounds okay with the comma and “and,” then the original sentence probably was a run-on. If it sounds ridiculous, then the sentence might not be run-on after all.
For this method of finding run-ons to work, students need to know what a pronoun is, and what a subject pronoun is. But the students who have the most trouble with run-ons in my experience have a weak understanding of English grammar. A pronoun? What’s that? A subject? What’s that?
Good luck.
English Writing Teacher 