Free HESI A2 Grammar guide
October 2026 - Punctuation Study Guide for nursing students in
Commas separate items and set off introductory or non-essential elements. Semicolons join related independent clauses, colons introduce lists or explanations, and dashes mark an abrupt break. A comma after an introductory phrase is nearly always correct; a comma between a subject and its verb nearly never is.
The four comma rules that cover almost everything
- In a series —
soap, water, and a clean towel. The comma before "and" is optional in general usage but standard in academic writing. - After an introductory element —
After the handover, the ward settled. - Around non-essential information —
The senior nurse, who had worked there for twenty years, disagreed.Remove the middle and the sentence still works. - Before a coordinating conjunction joining two independent clauses —
The ward was full, but every patient was seen.
Never put a single comma between a subject and its verb. The nurse on the evening shift, checked every chart is wrong however long the subject is. A pair of commas around an interruption is fine; one comma alone splitting the sentence is not.
Semicolon, colon, dash
| Mark | Use | Example |
|---|---|---|
| Semicolon | Joins two closely related independent clauses | The ward was short-staffed; handover ran late. |
| Semicolon | Separates list items that already contain commas | Leeds, Yorkshire; Bath, Somerset; Ely, Cambridgeshire |
| Colon | Introduces a list, an explanation or a quotation | She brought three things: gloves, a chart and a pen. |
| Dash | Marks an abrupt break or emphasis | He checked the dose — twice — before drawing it up. |
| Parentheses | Enclose an aside of lower importance | The dose (2 mg) was confirmed. |
The colon rule people miss
What comes before a colon must be a complete sentence. She brought: gloves, a chart and a pen is wrong, because "she brought" cannot stand alone. She brought three things: gloves, a chart and a pen is right.
The same test settles the semicolon. Both sides of a semicolon must be complete sentences — if either half could not stand alone, a semicolon is the wrong mark.
Essential and non-essential
This decides whether commas are needed at all, and it changes the meaning.
The nurse who wrote the note has left.— no commas. The clause identifies which nurse, so it is essential.The nurse, who wrote the note, has left.— commas. There is only one nurse in question; the clause is extra information.- Test by removing the clause. If the sentence loses essential meaning, leave the commas out.
Choosing between marks
Worked example
Punctuate: The audit found one recurring problem staff were not documenting the time of administration
- Identify the two parts: a complete statement, then what the problem was.
- The second part explains the first, which points to a colon.
- Check the colon rule: "The audit found one recurring problem" is a complete sentence, so a colon is permitted.
- A semicolon would also be grammatical here, but a colon signals explanation, which is the actual relationship.
The audit found one recurring problem: staff were not documenting the time of administration. The colon announces that what follows explains what came before.
Terms to know
- Comma
- Separates items and sets off introductory or non-essential elements.
- Semicolon
- Joins two independent clauses, or separates complex list items.
- Colon
- Introduces a list, explanation or quotation after a complete sentence.
- Dash
- Marks an abrupt break or adds emphasis.
- Parentheses
- Enclose an aside of lesser importance.
- Essential clause
- A clause that identifies which one is meant. No commas.
- Non-essential clause
- Extra information that could be removed. Takes commas.
- Serial comma
- The comma before the final "and" in a list.
What the HESI asks most
The same core ideas appear in different wording. If you can answer these without stopping to think, you have what this section requires.
Which sentence is punctuated correctly?
Check for a comma splice first, then a comma between subject and verb, then the colon rule.
Where should a comma be inserted?
After an introductory element, around a non-essential clause, or before a conjunction joining two clauses.
Which mark correctly joins these two clauses?
A semicolon if both halves stand alone; a colon if the second explains the first.
Key points
- Commas: series, after an introduction, around non-essential information, before a joining conjunction.
- Never a single comma between a subject and its verb.
- Both sides of a semicolon must be complete sentences.
- What comes before a colon must be a complete sentence.
- Essential clauses take no commas; non-essential ones do.
Review quiz
4 questions on this topic, each with the reasoning worked through. Pick an answer to see how it went, or open the explanation straight away.
-
Question 1 of 4
Which sentence is punctuated correctly?
Show the answer and explanation
Correct answer: B. The ward was short-staffed; handover ran late.
Both halves are complete sentences and closely related, which is exactly what a semicolon is for. The first is a comma splice, the third pairs a semicolon with a conjunction that is not needed, and the fourth separates a subject from its verb.
-
Question 2 of 4
Which sentence uses a colon correctly?
Show the answer and explanation
Correct answer: B. The trolley contained three items: gloves, gauze and tape.
What precedes a colon has to stand alone as a sentence, and "The trolley contained three items" does. "The trolley contained" does not, which rules out the first, and the remaining two place the colon inside the sentence rather than at the point of introduction.
-
Question 3 of 4
Which sentence needs commas around the underlined clause:
The nurse who wrote the incident report has been asked to attend.?Show the answer and explanation
Correct answer: B. It should stay as it is, because the clause identifies which nurse is meant.
The clause tells you which nurse of several, which makes it essential — and essential clauses take no commas. Adding them would imply that only one nurse exists and the detail is incidental, which changes the meaning.
-
Question 4 of 4
Where should a comma be added?
After reviewing the notes the consultant changed the plan.Show the answer and explanation
Correct answer: B. After "notes"
The introductory element ends at "notes", so the comma goes there to mark where the main clause begins. Placing it after "consultant" would split the subject from its verb, which is the one position a comma may never occupy.
Put this HESI topic into practice
Build a set on punctuation and use the rationale on every question to reinforce what you just reviewed.
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