In this guide
Run-on sentences are one of the most common problems in upper-elementary writing. Kids have lots of ideas and want to get them all down, so they keep going: "and then... and then... and then."
Fragments are the opposite problem: a piece of a sentence that's missing something it needs.
Both are easy to fix once kids know what to look for.
What is a complete sentence?
A complete sentence needs three things:
- A subject: who or what the sentence is about
- A verb: what the subject does or is
- A complete thought: it makes sense on its own
"The bus was late." Subject: the bus. Verb: was. Complete thought: yes.
What is a run-on sentence?
A run-on joins two or more complete sentences without the right punctuation or joining word.
Run-on: We went to the park we played soccer it started raining.
Comma splice: We went to the park, we played soccer.
A comma splice is a type of run-on: two complete sentences joined only by a comma. Kids often think a comma fixes the problem. It doesn't.
The read-aloud test
Have your child read their writing out loud, slowly. Wherever they naturally pause and their voice drops, there should probably be a period. If they run out of breath, there's likely a run-on.
The "can it stand alone?" test
Cover part of the sentence with a finger. If the part before and the part after could each be a sentence on its own, they need to be separated or properly joined.
Four ways to fix a run-on
1. Use a period. Make two sentences.
We went to the park. We played soccer.
2. Use a comma and a joining word. The joining words are for, and, nor, but, or, yet, so (often remembered as FANBOYS).
We went to the park, and we played soccer.
3. Use a linking word that shows the relationship.
After we went to the park, we played soccer.
We stopped playing because it started raining.
4. Cut the "and then" chain. Replace some "and thens" with time words: first, next, after that, finally. See our transition words guide for more.
Fix number 3 is the most powerful, because it shows how the ideas connect. That's what teachers mean by "flow."
What is a sentence fragment?
A fragment is missing a subject, a verb, or a complete thought.
Missing a subject: Ran to the store.
Missing a verb: The big red balloon.
Not a complete thought: Because I was hungry.
The most common fragment in kids' writing starts with a word like because, when, if or after. These words make the reader wait for more.
How to fix a fragment
Attach it to a nearby sentence, or add what's missing.
I ate two sandwiches because I was hungry.
The big red balloon floated over the school.
A quick self-check routine
Teach your child to check each sentence with three questions:
- Who or what is this about?
- What do they do or what are they?
- Does it make sense on its own?
If the answer to all three is clear, it's a sentence. If one sentence contains two full answers, it may be a run-on.
Try it: Fix these. My brother loves hockey he plays every Saturday. · When the bell rang. · I finished my homework, I watched a movie.
Why this matters
Clear sentence boundaries make writing easier to read and understand. Once kids stop writing run-ons, their ideas become easier to organize into paragraphs. Smart Little Writers starts with clear and concise sentences in Lesson 1 for exactly this reason, and Lesson 3 teaches kids to connect ideas logically instead of chaining them together.