As important as your voice is in your writing and your thesis is in providing the central argument or message you aim to support throughout your essay, writing cannot be clear without using good grammar. Your ideas are the most vital part of any essay; without strong ideas, an essay will not be impressive, no matter how well written it might be. But correct grammar is also important—it is what makes your writing understandable and direct.

There are many different grammar rules. You can’t possibly memorize them all, nor should you try. As a child you learned to speak without learning the “rules” of conversation by listening to others; you can also learn about grammar and language usage by reading. The more you read, the more you develop an “ear” for correct grammar. When you write, something will “sound” right or wrong to you. Try to read more frequently and trust your “ear” for correct grammar. If you have a serious problem with grammar, though, you may consider working with a peer or paid tutor.

Here is a list of some of the more common errors in grammar, punctuation, and language usage. These are errors you should particularly watch out for when you are proofreading your essay.

Homophones

Homophones are words that sound alike but have different spellings and meanings; they are extremely easy to confuse in your writing. Even when you proofread carefully, they can escape your attention and a computer’s spell-checker often cannot distinguish between them. Watch out for homophones and make certain you have chosen the correct word.

These are some of the most commonly confused homophones:

• its/it’s

• your/you’re

• two/too/to

• there/their/they’re

• whose/who’s

Spelling Errors

Here’s a list of frequently misspelled, commonly used words; you may even misspell them every time you use them without even realizing it.

absence

accessible

accommodate

acquaintance

achieve

across

appearance

athlete

bureaucracy

business

changeable

commitment

committed

conscience

definitely

difference/different

embarrass

emphasize

exaggerate

exercise

existence

exorcise

guarantee

half/halves

indefinitely

independent

indispensable

insistent

interpret

judgment (or judgement)

knowledge

loneliness

medicine

noticeable

occasionally

occur/occurred/occurrence

omit/omitted

parallel

peace/peaceable

perseverance

preference/preferred

prevalence

privilege

pursue

refer/referred/referring

repetition

rhythm

seize

self/selves

separate

significance

sophomore

succeed/successful

terrific

their

tragedy

transfer/transferred

undoubtedly

unnecessary

vacuum

worshipped

Most often, these words are misspelled because people get one or two letters wrong. Make certain you are familiar with these words so you can watch for them in your writing and double-check to see if they are correct.

Sentence Fragments

A sentence fragment is a group of words that does not function as a complete sentence. A complete sentence must consist of an independent clause—a group of words that includes a subject and verb and can stand on its own. The most common type of sentence fragment is one that lacks either a subject or verb. For example, “Justin’s soccer game,” or “Even though Ally had fun during her ballet class,” are not complete sentences.

You can usually correct a fragment by adding a subject or verb, or by joining together separate fragments and remembering to add a comma.

Justin’s soccer game lasted almost two hours.

Even though Ally had fun during her ballet class, she still had blisters on her toes.

When you proofread your essay, make certain each sentence has both a subject and a verb.

Run-On Sentences

Run-on sentences are the opposites of fragments. While a fragment does not contain an independent clause, a run-on sentence strings one clause or phrase after another, confusing the reader. A run-on is very confusing to read; you get lost somewhere in the middle of the sentence and forget what the whole thing is about. Most run-on sentences can be rewritten as two or three shorter sentences. Here is one that goes on and on:

Jacob continued to do math problems well into the night even when he felt too tired to do them he solved more and more and ate ice cream to keep himself awake and alert so that he could complete the entire assignment and also do the extra-credit question that the teacher required hoping that he could turn it all in on time.

As you can see, a run-on sentence is very confusing to read and the meaning gets jumbled around in your mind. Most run-on sentences can be rewritten in two or three shorter sentences, like this:

Jacob continued to do math problems well into the night. Even when he felt too tired to do them, he solved more and more. He ate ice cream to keep himself awake and alert so that he could complete the entire assignment and the required extra credit question. Jacob hoped that he could turn it all in on time.

Commonly Confused Expressions

The following list contains words or expressions that are frequently confused or misused. Most of them are homophones, words that sound the same but are spelled differently and have different meanings.

principle. A rule or law; a fact of nature.

principal. A person in authority, such as the head of a school. (Remember, the principal is your pal.)

capital. The seat of government (such as the city that is the state capital).

capitol. The building in which a governing body meets (as in the Capitol in Washington, D.C.).

affect. Used as a verb meaning to influence or to change. The noise affects my ability to think.

effect. Used as a noun, meaning the result of something. The noise produces a negative effect on my work.

stationary. Standing still.

stationery. Materials used for writing and typing. The clerk was stationary behind the stationery counter.

than. Used when comparing. My chemistry book is heavier than my Spanish book.

then. Used in reference to time; the next in order or time. Let’s go to lunch and then to the movies.

your. A possessive; refers to something you own.

you’re. A contraction of “you are.” You’re going to be late to pick up your car.

their. A possessive; refers to something they own. Their house is red with white trim.

there. Refers to location. I left my car over there.

they’re. Short for “they are.” They’re leaving in five minutes.

its. A possessive; refers to what “it” owns.

it’s. A contraction of “it is.” It’s fun to watch the dog fetch its toys.

quote. Used as a verb meaning to repeat something from another source.

quotation. Used as a noun meaning the reference that is repeated from another source. He proceeded to quote from the passage, and the quotation was quite long.

medium. A singular form of the word media referring to a single type of mass communication such as radio or television.

media. A plural form of the word medium that refers to several types of communication or to mass communication in general. Television is a medium that is far more influential and important than the other media.

Get to know the words on this list so you can watch out for them in your writing and double-check to make certain you use them correctly.

Pronoun-Antecedent Agreement

Pronouns (he, she, him, her, his, hers, their, theirs, it, its) take the place of nouns, and the nouns they refer to are called antecedents. Pronouns and antecedents must always agree, which means they must both be either singular or plural. For example:

Incorrect (Pronoun and antecedent do not agree)

      The students took his tests.

Correct (Pronoun and antecedent are both plural)

      The students took their tests.

There are two cases where this grammatical issue particularly becomes a problem: indefinite pronouns and generic nouns. An indefinite pronoun refers to a nonspecific person or thing, such as anybody, anyone, everybody, or someone. A generic noun represents a typical member of a group, such as a doctor, a student, or a New Yorker. Both of these antecedents are followed by singular pronouns: You should either use “he,” “she,” or “one” as the pronoun, or rewrite the sentence to avoid the problem.

Incorrect:

      When everyone has finished their exam, the test is over.

      A doctor must be considerate of their patients’ feelings.

Correct:

      When everyone has finished his or her exam, the test is over.

      A doctor must be considerate of his or her patients’ feelings.

      OR, Doctors must be considerate of their patients’ feelings.

Dangling Modifiers

Modifiers are words or phrases that describe or elaborate upon some other word or phrase. Dangling modifiers do not logically refer to any word in the sentence and therefore make the sentence incoherent. Be particularly careful when a sentence begins with a modifier; whatever subject follows the modifier must be the one the modifier refers to:

Incorrect:

      Originally performed in 1955, many people still consider Cat on a Hot Tin Roof to be Tennessee Williams’s greatest play.

In the above sentence, the modifier “originally performed in 1955” refers to the play Cat on a Hot Tin Roof, and not the “many people.” The sentence should therefore be rephrased:

Correct:

      Originally performed in 1955, Cat on a Hot Tin Roof is still considered by many people to be Tennessee Williams’s greatest play.

Split Infinitives

An infinitive form of a verb consists of two parts: the word “to” plus the verb. An infinitive is “split” when another word, usually an adverb, comes between them. Although certain constructions featuring split infinitives have come to be accepted, they generally sound awkward and disrupt the flow of a sentence. You should try to avoid them.

Split Infinitive:

      My parents taught me to never chew with my mouth open.

Intact Infinitive:

      My parents taught me never to chew with my mouth open.

Sentences Ending in Prepositions

Prepositions are certain words, usually appearing at the beginning of a phrase, that are used to describe or elaborate on some other word in the sentence. There are a limited number of prepositions in English. The most common include: about, above, across, after, against, along, among, around, as, at, before, behind, below, beside, between, but, by, concerning, despite, during, except, for, from, in, into, like, near, next, of, off, on, onto, out, over, regarding, respecting, since, than, through, throughout, to, toward, under, underneath, unlike, until, unto, up, upon, with, without.

It is generally considered poor grammar to end a sentence with a preposition. (Note though that this rule is changing and does not always apply today.) If a sentence ends with a preposition, try rephrase it if it does not sound even stranger, or try to place the preposition before the word it is modifying.

Incorrect:

      What room is it in?

      Ross wanted to be read to.

Correct:

      Where is it?

      Ross wanted someone to read to him.

Word Repetition

If you read an essay that uses the same words over and over, it can become quite boring and tedious. To make your writing more interesting for your reader, try to vary your choice of words as much as possible. You particularly want to use a sophisticated vocabulary that reflects your intelligence and expertise. To help increase word variety, you can use a thesaurus—a special dictionary of synonyms. You can buy a thesaurus in most bookstores to keep on your desk or use the one built into your computer.

When you edit your paper, look for any words that are repeated, especially within the same paragraph. Use the thesaurus to select alternatives. When using a thesaurus, you do need to be careful about which synonym you choose. Although synonyms have similar meanings, there are subtle differences that are important.

Certain words are also more appropriate for a particular context. Additionally, some of the synonyms in the thesaurus might be old-fashioned words not frequently used. If you include them in your essay, these words will stand out and disrupt the flow of your argument. You should therefore only choose synonyms that you know and are comfortable using in your writing. If necessary, look up some of the suggested synonyms in a dictionary in order to see the exact definition and appropriate context.