4 Tips for Avoiding Run-on Sentences

Run OnRun-on sentences are frequently encountered in the SAT writing section. If you know how to spot them, they are simple to correct. What makes a sentence a run-on? Do you remember when you were young and you wrote your first story? It probably went something like this:

My name is Dani and I like to dance and sing and play, my mommy and daddy are both really nice, I have two little brothers too and they are sometimes annoying but I love them anyway and I love my whole family.

After you handed this story into your teacher she may have remarked, “Great Job, but where are the periods?”. A sentence is a run-on if it is composed of two full sentences that are separated by a comma. Let’s look at this example sentence:

My friend Mary loves to shop in designer stores, she is very stylish.

On either side of the comma is a full sentence. Each one has its own subject and verb. Because each part can stand on its own, the sentence is a run-on and grammatically incorrect. There are four ways to correct a run-on sentence. Only three appear commonly on the SAT, but it is good to know all four for general writing.

  1. Replace the comma with a period: This is probably the simplest way to correct a run-on. Since the SAT only tests one sentence per question, this will rarely, if ever, be a correct answer on the SAT exam.
  2. Replace the comma with a semi-colon:A semi-colon acts like a weak period and often separates two closely related ideas. To correct a run-on sentence, you can simply replace the comma with a semi-colon. However, before choosing an answer choice with a semi-colon, you must make sure that the clauses before and after the semi-colon are full sentences. If not, then the semi-colon is grammatically incorrect and the answer choice wrong.Incorrect: Because my friend Mary loves to shop in designer stores; she is very stylish.
    Correct: My friend Mary loves to shop in designer stores; she is very stylish.
  3. Replace the comma with a colon:A colon will most often appear before introducing a list or main thought. For example, in the third paragraph of this blog I use a colon to introduce the example sentence. A colon is also used to introduce a list. As you can see in this example, the clauses before and after a colon do not have to be full sentences.
    Example: These are some things I like to do: dance, sing, and act.
  1. Add a conjunction to the comma: A good way to remember common conjunctions is by the acronym FANBOYS. This stands for seven common conjunctions: for, and, nor, but, or, yet, so. When one of these is added to a run-on sentence, it causes one part of the sentence to become dependent on the other.Therefore, the sentence is no longer comprised of two independent clauses separated by a common. For example, I can fix my pervious run on sentence by adding the conjunction “so”. Now the sentence reads:

    My friend Mary loves to shop in designer stores so, she is very stylish.

    Keep in mind that conjunctions are not interchangeable and must be used in specific contexts. In this sentence, “so” can be used because the second part of the sentence reinforces the first part. The conjunction “but” would not make sense because it would indicate a contrast that is not present in the sentence.

    Incorrect: My friend Mary loves to shop in designer stores but, she is very stylish.

Now that you know what a run-on sentence is, you can always check for it in the SAT writing section. If you see two clauses and a comma, make sure that they are not full sentences. If they are, you know four great ways to fix the sentence. Don’t let those run-on sentences keep running! For tips on Parallelism, check out this article.

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Danielle Kipnis is a Veritas Prep SAT instructor based in Miami. She is a native New Yorker who then majored in England and Dance at Northwestern University. At Northwestern, she founded the dance company Steam Heat. She now continues to dance, choreograph, and satiate her love for teaching through SAT prep.