HESI A2
HESI A2 Grammar Rules You Must Know: The Complete Guide
By Tutoriffic Team · Published on 2026-03-15
The HESI A2 Grammar section tests 50 questions in 50 minutes. Unlike math, there are no formulas to memorize — but there are specific, predictable rules that the exam tests over and over. Master these 15 rules and you'll handle the vast majority of grammar questions correctly.
How the HESI A2 Grammar Section Works
The Grammar section asks you to identify errors or choose the correct version of a sentence. Question formats include:
- Error identification: "Which word or phrase contains a grammatical error?"
- Sentence correction: "Which sentence is grammatically correct?"
- Fill in the blank: "Choose the word that correctly completes the sentence."
The grammar rules below are listed in order of frequency — the rules at the top appear on almost every HESI exam.
Rule 1: Subject-Verb Agreement
The subject and verb must agree in number. Singular subjects take singular verbs; plural subjects take plural verbs.
❌ The group of nurses are meeting today.
✅ The group of nurses is meeting today. ("Group" is singular.)
Trap to watch for: Prepositional phrases between the subject and verb. "The box of supplies is heavy" — the subject is "box," not "supplies."
Rule 2: Comma Splices & Run-On Sentences
Two independent clauses cannot be joined by just a comma — that's a comma splice. Fix with a period, semicolon, or comma + conjunction.
❌ The patient was stable, the nurse documented the vitals.
✅ The patient was stable; the nurse documented the vitals.
✅ The patient was stable, and the nurse documented the vitals.
Rule 3: Apostrophes — Possession vs. Plural
Apostrophes show possession, not plural. This is one of the most commonly missed rules:
❌ The nurse's attended the meeting. (Wrong — this means possession)
✅ The nurses attended the meeting. (Plural, no apostrophe)
✅ The nurse's stethoscope was on the desk. (Possession — correct)
Special case: its (possessive) vs. it's (it is). "The hospital updated its policy." "It's important to wash hands."
Rule 4: Pronoun Agreement
Pronouns must agree with their antecedent in number and gender:
❌ Each student must bring their textbook.
✅ Each student must bring his or her textbook. ("Each" is singular.)
Note: While "their" as a singular pronoun is acceptable in casual English, the HESI follows traditional grammar rules where "each," "every," "anyone," and "everyone" are singular.
Rule 5: Sentence Fragments
A complete sentence needs a subject, a verb, and expresses a complete thought. Fragments are incomplete sentences:
❌ Because the patient refused treatment. (Fragment — dependent clause)
✅ The doctor was concerned because the patient refused treatment.
Rule 6: Semicolons
Semicolons connect two independent clauses that are closely related. Don't use a semicolon before a dependent clause or after a conjunction.
✅ The test was difficult; many students failed.
❌ The test was difficult; because it covered new material.
Rule 7: Commonly Confused Words
The HESI frequently tests these pairs — memorize the differences:
| Word | Meaning | Example |
|---|---|---|
| affect | verb: to influence | Stress affects sleep. |
| effect | noun: a result | The effect was immediate. |
| than | comparison | She scored higher than me. |
| then | time/sequence | Study first, then test. |
| their | possessive | Their scores improved. |
| there | location | The chart is over there. |
| they're | they are | They're taking the HESI. |
Rule 8: Parallel Structure
Items in a list or comparison must be in the same grammatical form:
❌ The nurse enjoys running, swimming, and to hike.
✅ The nurse enjoys running, swimming, and hiking.
Rules 9-15: Quick Reference
- Rule 9 — Colon usage: Use after a complete sentence to introduce a list or explanation. "She packed three things: a pen, a calculator, and her ID."
- Rule 10 — Who vs. Whom: Who = subject (acts). Whom = object (receives action). "To whom was the report sent?"
- Rule 11 — Active vs. Passive voice: Active voice is preferred. "The nurse administered the medication" (active) vs. "The medication was administered by the nurse" (passive).
- Rule 12 — Dangling modifiers: The modifier must clearly relate to the subject. ❌ "Walking to the hospital, the rain started." ✅ "Walking to the hospital, she got caught in the rain."
- Rule 13 — Double negatives: Don't use two negatives. ❌ "She didn't have no supplies." ✅ "She didn't have any supplies."
- Rule 14 — Verb tense consistency: Don't shift tenses mid-sentence. ❌ "She studied the material and takes the test." ✅ "She studied the material and took the test."
- Rule 15 — Comma before coordinating conjunctions: Use a comma before FANBOYS (for, and, nor, but, or, yet, so) when joining two independent clauses.
5-Day HESI Grammar Study Plan
- Day 1: Rules 1-3 (subject-verb agreement, comma splices, apostrophes). Practice 20 questions.
- Day 2: Rules 4-6 (pronouns, fragments, semicolons). Practice 20 questions.
- Day 3: Rule 7 (confused words) + Rules 8-9 (parallel structure, colons). Practice 20 questions.
- Day 4: Rules 10-15 (who/whom, voice, modifiers, negatives, tense, comma rules). Practice 20 questions.
- Day 5: Take a full HESI practice quiz. Review every wrong answer and revisit the relevant rule.
For additional HESI preparation, see our guides on HESI A2 Math Formulas, HESI A2 Vocabulary, and HESI A2 Anatomy & Physiology.
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