Grammar Guide I: Most Common Grammar Mistakes

The most common college writing mistakes, and how to fix/avoid them

Wrong Word

What this means: the word may convey a slightly different meaning than you believe it does, or it may mean something completely different altogether.

Example: “Perspective” and “Prevalence”: similar words, very different meaning

How to fix/avoid this common mistake: Make sure to check a thesaurus for any words you are unsure of, and do not ignore spell/grammar checks on your writing device. Have a peer read the work aloud as well. 

 Missing Comma After Introductory Element

What this means: After you introduce a sentence or clause, there needs to be a comma so that the reader knows where the rest of the sentence begins.

Example: “Determined to pass the class I studied every day.” should be “Determined to pass the class, I studied every day.”

How to fix/avoid this common mistake: When you read a sentence, make sure you can separate the subject from the rest easily. If not, the introductory element most likely needs a comma after it. When you are using a phrase to introduce the start of your sentence, there should always be a comma to break it up.

Missing of In-Text Citations/Documentation

What this means: This occurs when you don’t add where you get your information in your paper or quote words that aren’t your own. Even though you may have a reference list at the end of your paper on a separate page you must still add in-text citations. 

Example: There is going to be a new model of Toyota coming in 2022. If this isn’t in your own words, you need to put this in quotations and mention the source.  

How to fix/avoid this common mistake: Remember to make sure you quote words in your paper that aren’t your own or paraphrase your information, putting it in your own words. Also, mention the source.

Vague Pronoun Reference 

What this means: This is when pronouns (he, she, it) should be able to be easily related to being put in the place of a noun which is the antecedent. In situations where the antecedent is a few words or unidentifiable, make it simpler to understand. 

Example: The NFL changed its helmet policy, making some players resentful.

How to fix/avoid this common mistake: Make sure to identify what the players resented.


What this means: Although we have technical resources that will look over the mistakes we made in our paper, please realize that these resources may not catch all of them. This leads to common errors like the example below.

Example: We went to the Parkers’ house to enjoy there barbecue.

How to fix/avoid this common mistake: Take time to read over the paper yourself instead of relying on technology.

Mechanical Error with a Quotation

What this means: When you use someone else’s words without signaling that they aren’t your own, this is when this error takes place. This means you forgot to put quotation marks (“,”) around the quote. 

Example: Edgar Allan Poe stated we loved with a love that was more than love.

How to fix/avoid this common mistake: When you get to the person’s quote, start it as a new sentence and use quotations.

Unnecessary Comma

What this means: Sometimes when writing you add a comma because you think that it belongs in the sentence, but it actually just obscures the meaning.

Example: Many people, who enjoy TV, spend their time on the couch. 

How to fix/avoid this common mistake: Do not use commas to separate elements that need to be together to make sense, and do not use a comma after an “and” or “but” when those conjunctions do not separate the sentence into two parts. 

Faulty Sentence Structure

What this means: Starting out a sentence with one structure, and then ending it with another type.

Example: “The information that families have access to is what financial aid is available and thinking about the classes available, and how to register.”

How to fix/avoid this common mistake: Make sure to maintain a consistent grammatical pattern throughout your sentence, and read it out loud to ensure that it flows properly.

Unnecessary Shift in Verb Tense

What this means: Shifting between tenses in the middle of a sentence.

Example: She loved birds, she takes photos of them outside every morning on her walk. 

How to fix/avoid this common mistake: Make sure to check your sentences and if they are in present tense, keep the verbs in present tense throughout the entire sentence.

Comma Splice

What this means: Using only a comma to separate two clauses that could be in their own individual sentence. 

Example: Emily loves going to the park, she spends a lot of time reading under a tree when she goes to the park. 

How to fix/avoid this common mistake: Use a semicolon or period to separate the sentences and let them stand alone!

Run-on Sentence

What this means: Joining clauses that could stand alone without any punctuation in between them.

Example: Emily loves going to the park she spends a lot of time reading under a tree when she goes to the park.

How to fix/avoid this common mistake: Add a semicolon or period to split up the clauses.

Poorly Integrated Quotation

What this means: This is when quotes are just thrown into the paper without properly signaling that you’re adding them in first.

Example: “There is not enough time for them to change their ways on such short notice.”

How to fix/avoid this common mistake: In the sentence, say where you got the quote from before you quote your source.

Missing or Unnecessary Hyphen

What this means: Compound adjectives may or may not need hyphens depending on if it supports the noun coming with it.

Examples: There was a mouse-eating snake in the woods earlier.

There was a mouse eating snake in the woods earlier.

How to fix this/avoid this common mistake: Pay attention to if your adjectives are needed to represent the noun. 

Sentence Fragment

What this means: These occur when a sentence has a part in it that is put as a separate sentence when it should be a part of the whole sentence.

Example: Mark came home with much dirt on his clothes. From playing in the park all day.

How to fix/avoid this common mistake: Include the second sentence in the first because the second sentence doesn’t make sense on its own.  


Unnecessary or Missing Apostrophe (including its/it’s)

What this means: When a noun owns something, an apostrophe and s (Will’s watch) or the apostrophe by itself (mens’ sports) is needed. Some possessive pronouns don’t require apostrophes like these for example: his, hers, theirs. “Its” refers to something being owned by it and “it’s” refers to it is/ it has meaning.

Examples: Make sure to have Milo’s dog food ready by dinner time. The mens’ 100 meter dash is coming up soon.

How to fix/avoid this common mistake: Remember to that nouns that own with no “s” at the end of it need that and an apostrophe; just add apostrophes to words ending in “s.’” 

Missing Comma with a Nonrestrictive Element

What this means: Nonrestrictive phrases include extra text that a   sentence doesn’t need for the meaning of it. Commas are needed to tell them apart from the rest of the sentence. 

Example: Mike the best player on the court hit a buzzer beater. The clause needing commas around it in the sentence is “the best player on the court.”  Mike, the best player on the court, hit a buzzer beater. 

How to fix/avoid this common mistake: If extra words in the sentence can be avoided, then you shouldn’t add them in there. However, if need be, red over the sentence with extra words to determine if a certain clause needs commas around it.