Common Grammar Mistakes in Academic Writing (and How to Fix Them)

Most grammar errors in student essays come from a small set of patterns, and once you know them you can catch them yourself. This guide covers the eight we see most often in the work of international and ESL students, with an incorrect and a corrected example for each. Fixing these does not change your ideas. It stops small errors from hiding them.

1. Missing or Wrong Articles

Articles (a, an, the) cause more errors for ESL writers than almost anything else, especially if your first language has no articles. Use a/an for one non-specific countable noun, the for something specific that the reader can identify, and no article for general plural or uncountable nouns.

Here the statements are general, so no article is needed before technology or education.

2. Wrong Prepositions

Prepositions rarely translate word for word, so the correct one has to be learned together with the word it follows.

Keep a list of verb + preposition and adjective + preposition pairs you meet in your reading, such as depend on, different from and responsible for.

3. Subject-Verb Agreement

The verb must agree with its true subject, not with the noun closest to it. Mistakes appear most often in long sentences.

Each takes a singular verb, so use was here.

4. Inconsistent Tense

Choose a tense for each part of your paper and keep to it. Describing past research and your own method usually takes the past tense, while general facts and your claims about what a source says often take the present. Departments differ, so check your style guide.

The study took place in the past (examined, found); the general conclusion is still true, so improves stays in the present.

5. Uncountable Nouns Used as Plurals

Words such as information, research, evidence, advice, feedback and equipment have no plural form and take a singular verb.

Use pieces of or a body of to count them: two pieces of evidence, a body of research.

6. Run-On Sentences and Comma Splices

A comma alone cannot join two complete sentences. Use a full stop, a semicolon, or a comma with a conjunction such as and or but.

Other correct options: The experiment failed. The team repeated it. or The experiment failed; the team repeated it.

A word such as however or therefore between two complete sentences needs a semicolon or full stop before it and a comma after it.

7. Informal Language and Contractions

Academic writing avoids contractions, slang and vague phrases such as a lot of and things.

8. Easily Confused Words

Spell checkers will not catch a correctly spelled wrong word.

Affect is usually a verb and effect a noun. Their shows ownership; there points to a place or introduces a sentence.

A Quick Self-Check

• Does every singular countable noun have a, the or another determiner?
• Does each verb agree with its real subject?
• Is the tense consistent within each section?
• Have you used any plural form of information, research or evidence?
• Are there any comma splices or contractions?
• Have you read the essay aloud once?

Grammar is only one layer. If the argument itself feels unclear, see our guide on proofreading vs editing to decide what to fix first, and learn how to paraphrase without plagiarising when you rephrase sources in your own words.

When to Get a Second Pair of Eyes

A fresh reader notices patterns you have stopped seeing. If English is not your first language, a language and clarity edit before submission can catch the errors above and show you each change as a tracked edit, so you learn from them. Your ideas and voice stay yours.

Frequently Asked Questions

What are the most common grammar mistakes in academic essays?

The most frequent ones are article errors (a, an, the), wrong prepositions, subject-verb agreement slips, inconsistent tense, treating uncountable nouns like information and research as plural, and run-on sentences joined only by a comma.

Why are articles so difficult for ESL writers?

Many languages, including Russian, Chinese, Japanese and Swahili, have no articles or use them differently, so there is no direct rule to transfer. Reading widely in academic English and checking each noun for 'which one?' and 'how many?' helps.

Should I use a grammar checker for my essay?

A grammar checker is useful for catching obvious slips, but it misses context errors such as wrong prepositions, unclear sentences and incorrect word choice. Treat it as a first pass and read the essay again yourself.

Do contractions belong in academic writing?

In most formal essays, no. Write 'do not' instead of 'don't' and 'it is' instead of 'it's', unless your department's style guide says otherwise.

Will editing change my writing voice?

A good language editor corrects grammar, clarity and flow while keeping your ideas, argument and voice. You should see tracked changes so you can accept or reject each one and learn from them.