Run-Ons and Comma Splices- Exercises and Corrections
Run-Ons and Comma Splices: The Sentence Errors Nobody Warns You About
You learned about run-on sentences in middle school. You probably forgot half of it by next week. Now you're older, you're writing professionally, and an editor just flagged your prose for "comma splices." Time to actually learn the difference.
This isn't a gentle refresher. It's the bare minimum you need to fix these errors and never make them again.
What Is a Run-On Sentence?
A run-on sentence is exactly what it sounds like: two complete sentences slammed together without any punctuation to separate them. No period. No semicolon. Just a collision.
Example:
I love coffee I can't function before noon.
That "I love coffee" is a full sentence. "I can't function before noon" is a full sentence. They need separation. They don't have it. That's a run-on.
Run-ons happen because people hear the sentence in their head as one complete thought. Writing it out reveals the break. Always read your work aloud. You'll catch these instantly.
What Is a Comma Splice?
A comma splice is a specific type of run-on. It's when you join two independent clauses using only a comma. The comma isn't strong enough for that job. You need something heavier.
Example:
I love coffee, I can't function before noon.
Both parts can stand alone as complete sentences. A comma between them doesn't fix that. It's a band-aid on a broken bone.
How to Fix Both Problems
Four methods. Pick the one that fits your sentence and style.
1. Split Into Two Sentences
Add a period where the break naturally occurs.
Original: She finished the report she sent it to the client.
Fixed: She finished the report. She sent it to the client.
This is the cleanest fix for most situations.
2. Use a Semicolon
Use a semicolon when the two clauses are closely related in meaning.
Original: The project was late, the team worked overtime to finish.
Fixed: The project was late; the team worked overtime to finish.
Semicolons work best when the second clause explains or continues the thought of the first.
3. Add a Conjunction
Use a coordinating conjunction: and, but, or, nor, for, yet, so.
Original: He missed the train, he arrived late to the meeting.
Fixed: He missed the train, so he arrived late to the meeting.
The conjunction shows cause and effect. It makes the relationship between clauses explicit.
4. Make One Clause Dependent
Turn one independent clause into a dependent clause by adding a subordinating conjunction like although, because, when, while, or since.
Original: The coffee was cold, I drank it anyway.
Fixed: Although the coffee was cold, I drank it anyway.
This method adds nuance. Use it when you want to emphasize one clause over the other.
Comparing the Fix Methods
| Method | Best For | Example |
|---|---|---|
| Two sentences | General use, clarity | It rained. We stayed inside. |
| Semicolon | Related ideas, parallel structure | It rained; we stayed inside. |
| Conjunction | Showing cause/effect, contrast | It rained, so we stayed inside. |
| Dependent clause | Emphasis, nuance | Because it rained, we stayed inside. |
Exercises and Corrections
Fix these sentences yourself before checking the answers. No peeking.
Exercise 1
The meeting started at nine we were all still having breakfast.
Show Answer
The meeting started at nine, but we were all still having breakfast.
Or: The meeting started at nine. We were all still having breakfast.
Exercise 2
She studied for hours she still failed the exam.
Show Answer
She studied for hours, yet she still failed the exam.
Or: She studied for hours. She still failed the exam.
Exercise 3
The software crashed all our work was lost.
Show Answer
The software crashed, and all our work was lost.
Or: The software crashed. All our work was lost.
Exercise 4
I wanted to go outside, the weather was terrible.
Show Answer
I wanted to go outside, but the weather was terrible.
Or: Although I wanted to go outside, the weather was terrible.
Exercise 5
He didn't check his email, he missed the deadline.
Show Answer
He didn't check his email, so he missed the deadline.
Or: He didn't check his email. He missed the deadline.
How to Spot These Errors in Your Own Writing
Don't rely on spell-check. It won't catch comma splices. Here's what works:
- Read aloud. Your ear will catch the awkward pause where a period belongs.
- Circle every comma. If a comma separates two complete thoughts, it's a potential splice. Check what follows it.
- Count subjects and verbs. Every independent clause has its own subject-verb pair. Two pairs, two clauses. You need proper punctuation between them.
- Write shorter sentences. Most run-ons come from trying to pack too much into one sentence. Shorter sentences force clarity.
Getting Started: Fix Your Current Draft
Take your last piece of writing. Go through it sentence by sentence. For each sentence longer than two lines, ask:
- Does this contain more than one complete thought?
- Are those thoughts joined by only a comma?
- Is there a natural break where I could add a period?
Fix what you find. Read it again. The errors will become obvious once you know what to look for.
That's it. Fix the errors. Move on.