HESI A2 Grammar: Rules, Common Mistakes, and Practice Strategies

The HESI A2 Grammar section is one of the easiest places to raise your score, because the rules it tests are finite, consistent, and learnable. Most students who struggle with grammar do not struggle because the concepts are hard. They struggle because they never sat down to learn the rules systematically.

This guide covers the exact rules the section tests most: subject-verb agreement, pronoun case, comma splices, punctuation, and the commonly confused word pairs that appear every single year. If you combine these rules with timed practice, you can turn grammar into one of your strongest sections. For the rest of the exam, start with our HESI A2 study guide.

What the Grammar Section Tests

The Grammar section has 50 scored questions plus a few unscored pilot items, and you get about 50 minutes to complete it. The questions focus on standard written English, and they test grammar where it changes what a sentence means rather than where it is only a matter of style.

The grammar section groups the tested topics into eight areas: parts of speech, punctuation, plurals, sentence structure, sentence rearrangement, modifiers, and coherence in writing. In practice, five rules account for most of the questions you will see.

Subject-Verb Agreement

A verb must agree with its subject in number. Singular subjects take singular verbs, and plural subjects take plural verbs. The mistakes on the exam hide in sentences where a phrase comes between the subject and the verb.

• Correct: The box of supplies is in the storage room.
• Incorrect: The box of supplies are in the storage room.

In that example, the phrase "of supplies" sits between the subject "box" and the verb, so it is easy to match the verb to the wrong noun. The subject is "box", which is singular, so the verb must be "is".

Watch for these special cases:

• Indefinite pronouns such as each, every, either, neither, and everyone are singular. Each of the nurses is responsible for her patients.
• Either/or and neither/nor match the verb to the closer subject. Neither the manager nor the nurses are available.
• Collective nouns such as team, staff, and group are singular when they act as one unit. The staff is meeting at noon.
• Sentences that start with there are or there is match the verb to the noun that follows. There are three patients waiting.

Pronoun Case and Reference

Pronouns must match their role in the sentence. Subjective pronouns (I, he, she, we, they) act as subjects. Objective pronouns (me, him, her, us, them) act as objects. Possessive pronouns (my, his, her, our, their) show ownership and never use apostrophes.

• Correct: She and I reviewed the chart.
• Incorrect: Her and me reviewed the chart.
• Correct: The manager gave the files to him and me.

A quick trick for pronoun pairs: remove the other person and read the sentence alone. If you would say "I reviewed the chart" and not "me reviewed the chart", then "She and I" is correct.

Pronoun reference matters too. Every pronoun must clearly point back to one noun. The sentence "The nurse told the patient that his results were ready" is ambiguous because "his" could refer to either person. Rewrite it to remove the confusion: "The nurse told the patient that the patient's results were ready."

The Most Common Mistake: Comma Splices and Run-Ons

Two complete sentences cannot be joined with only a comma. That error is called a comma splice, and it is almost always the incorrect option on the exam.

• Comma splice: The shift ended at midnight, the nurse drove home.
• Fixed with a period: The shift ended at midnight. The nurse drove home.
• Fixed with a conjunction: The shift ended at midnight, and the nurse drove home.
• Fixed with a semicolon: The shift ended at midnight; the nurse drove home.

A run-on sentence is the same problem without the comma: "The shift ended at midnight the nurse drove home." Any answer choice that joins two full sentences with only a comma or with nothing at all is wrong.

Punctuation That Changes Meaning

Three punctuation marks carry most of the grammar questions.

Commas: use a comma before a conjunction such as and, but, or or when it joins two complete sentences. Use commas around nonessential phrases, the ones you could remove without changing the core meaning. Do not use a comma between a subject and its verb.

Semicolons: a semicolon joins two complete sentences without a conjunction. If one side cannot stand alone, the semicolon is wrong.

• Correct: The patient was stable; his vitals improved overnight.
• Incorrect: The patient was stable; and his vitals improved overnight.

Apostrophes: the apostrophe shows possession or contraction, and the exam loves to test the difference. The nurse's station is the station of one nurse. The nurses' station is the station of several nurses. Its is possessive, while it's means it is. Their is possessive, while they're means they are.

Commonly Confused Word Pairs

These pairs appear on the HESI A2 every year. Learn each one once, and you bank points.

Pair	Use	Example
Affect / Effect	Affect is a verb meaning to influence; effect is a noun meaning a result	The medication affects heart rate. The effect was immediate.
Their / There / They're	Their is possessive; there is a place; they're means they are	Their shift ended. The chart is over there. They're on call tonight.
Its / It's	Its is possessive; it's means it is	The heart pumps its own blood. It's a common condition.
Lie / Lay	Lie means to recline; lay means to place something	The patient lies in bed. Lay the blanket on the bed.
Accept / Except	Accept means to receive; except means excluding	The school accepts all scores except expired ones.
Then / Than	Then is time; than is comparison	We checked the vitals, then updated the plan. This drug works faster than the old one.
To / Too / Two	To is direction; too means also or excessively; two is the number	Go to the lab. The test was too long. Two samples were sent.
Who / Whom	Who is a subject; whom is an object	Who called? To whom should I give the form?
Between / Among	Between is for two; among is for three or more	The choice is between two drugs. Share the tasks among the team.
Farther / Further	Farther is physical distance; further is degree or extent	The clinic is farther down the road. We need further review.
Fewer / Less	Fewer is for countable items; less is for amounts	Fewer errors, less stress.
Compliment / Complement	Compliment is praise; complement is something that completes	She complimented the staff. The new wing complements the hospital.

How to Spot Errors Quickly

The HESI A2 grammar resource from the University of Nevada, Reno suggests a simple habit that works on test day: identify the main verb of the sentence first. Almost every other grammar question becomes easier once you know the verb, because the verb tells you the subject and the clause structure.

• Read the entire sentence before looking at the answer choices.
• Find the main verb, then ask who or what is doing the action. That is your subject, and the verb must agree with it.
• Decide whether the sentence has one clause or two. That determines whether a comma, conjunction, or semicolon is needed.
• For confused word pairs, substitute the meaning. If the sentence is about a result, effect is correct; if it is about influencing, affect is correct.
• When a choice "sounds wrong" only because of style, keep it. The exam tests meaning, not preference.

Practice Strategies That Raise Your Score

Grammar improves fastest with rule-based practice rather than passive reading:

• Learn the rules in this guide one at a time, and write your own example for each rule. Writing forces recall.
• Do 20 to 30 practice questions a day, and read the explanation for every question, including the ones you got right.
• Keep a personal error log. Write down each rule you miss and review the log before each practice session.
• Rewrite short news paragraphs in your head, fixing every punctuation choice, to build speed with sentence structure.
• Take at least one full timed grammar practice test before exam day so the 50-question pace feels normal.

Ready to practice? Our HESI A2 prep page includes grammar practice tests built around the real format, and our high-yield vocabulary list covers the sister section that pairs with grammar on the exam.

Final Thoughts

The HESI A2 Grammar section rewards students who learn rules instead of relying on what sounds right. Master subject-verb agreement, pronoun case, comma splices, and the confused word pairs in this guide, then practice under real timing. Grammar is one of the most predictable sections on the exam, and predictable sections are where prepared students separate themselves.