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Common Grammar Mistakes in College Essays

grammar mistakes in college essays
There are two types of people: those who make grammatical errors and those who hate them. It shouldn’t surprise you when I say your college professors and TAs are likely to be in the latter category. Well, if you don’t have perfect grammar, there’s still a chance you will learn. While you do, here are a select few of the most pervasive and annoying grammar errors in college essays.

Comma splicing

Comma splices occur when you join two independent clauses (two complete sentences) with a comma, rather than a period or a semicolon. This is a pretty serious mistake. For some reason, it’s more acceptable with young people, but your older professors will surely be sticklers for this one.

Correct: John had tea, and Jane had coffee.
Incorrect: John had tea, Jane had coffee.

As you can see, the correct version uses a coordinating conjunction to connect the two sentences. Coordinating conjunctions are words like and, or, but, so, etc. Use them to connect sentences, and put commas before each one. Words like however, nonetheless, therefore and furthermore are transitional words, and not coordinating conjunctions. Use them to set off a new sentence, rather than a new clause.

Split infinitives

Infinitives are verbs that have ‘to’ before them. Split infinitives occur when you separate ‘to’ and the verb with another word.

Correct: Jane told John to take out the trash immediately.
Incorrect: Jane told John to immediately take out the trash.

This rule is a favorite of English snobs. In reality, it’s not a hard-and-fast rule, merely a suggestion. Still, you should treat it as a rule, since your instructors probably do.

Possessive mistakes

Surprisingly, this is an extremely common error. It’s also the one that drives teachers up the wall, since it’s such a simple mistake. Possessives use apostrophes to indicate ownership. Use an apostrophe before an -s when referring to an object that belongs to a singular someone.

Correct: Jane’s coffee. (coffee belonging to Jane)
Incorrect: Janes’ coffee. (coffee belonging to all Janes)

Correct: The Smiths’ car broke down.
Incorrect: The Smiths’s car broke down.

Since The Smiths is already plural with an -s at the end, there is no need to add an apostrophe and an -s, just an apostrophe will be sufficient.

Their, there and they’re

Lots of the mistakes made by college students involve words that sound the same, but mean different things. ‘Their’ indicates ownership by ‘them’, ‘there’ is a location, and ‘they’re’ is a contraction of ‘they are’. Easy enough to remember.

Correct: Their coffee is the best.
Incorrect: There coffee is the best.


An alarmingly widespread mistake that’s only considered egregious because everyone’s supposed to have learned this in middle school. Remember, ‘less’ refers to things that are uncountable (like water, sugar and other substances), and ‘fewer’, conversely, refers to things the are countable (words, hours, apples, etc.).

Correct: You can write 4 paragraphs or fewer.
Incorrect: You can write 4 paragraphs or less.

English language evolves and now we can hear something like “Your essay should be 500 words or less”. However, your professors expect you to use grammar correctly, so follow the rules, not tendencies when writing your college essay.

Run-on sentences

Run-on sentences are sentences consisting of multiple independent clauses that are not properly joined by punctuation or coordinating conjunction. Essentially, if you write like most people speak, you’ll end up with run-on sentences. They are best avoided, unless you’re writing dialogue, and if the goal of your essay is to convey ideas, not confuse your reader.

Correct: I went to the supermarket, bought cheese and pasta, and met my friend Jane.
Incorrect: I went to the supermarket bought cheese and pasta and met my friend Jane.

Vague pronoun usage

Almost everyone suffers from this, especially when pressed for time. To avoid this, re-read what you wrote and make sure that it’s clear who your pronouns are referring to.

Correct: Mike was told that his permit had expired the previous weekend by John.
Incorrect: John told Mike his permit had expired the previous weekend.

As you can see, in the incorrect example, we cannot infer clearly who ‘his’ is referring to.


A very common mistake, and not just with college students, is not knowing when to use ‘me’ and when to use ‘I’.

Correct: My sister and I went to the zoo.
Incorrect: My sister and me went to the zoo.

This one is very simple: just take out the other person or people in the sentence, and you’ll know which one to use. ‘Me’ went to the zoo? No, ‘I’ did!

This is by no means an exhaustive list, but these are the mistakes that are most annoying, especially to your professors who are forced to see them over and over. Remembering these rules is easy, but you should know that truly perfect grammar comes from lots of reading and writing, so do more of both. Good luck!