Run‑on sentences

The rule in one minute

A run-on sentence (also called a fused sentence) is two or more complete sentences pushed together with no punctuation between them.

The alarm rang everyone rushed out of the building. Here, the alarm rang is a full sentence and everyone rushed out of the building is a full sentence. Nothing marks the boundary, so the reader must work out where one idea ends.

A run-on is close to a comma splice. The splice puts a comma at the join, but the run-on leaves it bare.

Both have the same cause: the writer has not marked where a sentence stops. The first job is to see the missing boundary.

Why it costs marks

Examiners read for boundary control when they judge accuracy. A run-on is the plainest boundary failure.

A script full of fused sentences cannot reach the higher accuracy bands. In ESL writing, correctness is marked directly, so run-ons stand out.

They also tend to repeat: a student who fuses one pair often fuses several. They cost marks even when the thinking is good.

Examples

One fused sentence, fixed three ways:

• Run-on: The film was too long I nearly fell asleep.
• Full stop: The film was too long. I nearly fell asleep.
• Semicolon: The film was too long; I nearly fell asleep.
• Joining word: The film was too long, so I nearly fell asleep.

More examples:

• Wrong: She trained every morning her times kept improving. Right: She trained every morning, and her times kept improving.
• Wrong: The recipe looked simple it took the whole afternoon. Right: The recipe looked simple, but it took the whole afternoon.
• Wrong: We waited by the gate the coach never came. Right: We waited by the gate. The coach never came.

Find the fault

Which sentences run on? Fix them, then check below.

1. The market was busy vendors called out from every stall.
2. Although the road was blocked, we found another way home.
3. He forgot his umbrella he arrived soaked to the skin.
4. Reading aloud helps you hear your own mistakes it also slows you down enough to catch them.

Answers: (1) Run-on. The market was busy, and vendors called out from every stall. (2) Correct. Although makes the first part a dependent clause, so there is no boundary error. (3) Run-on. He forgot his umbrella, so he arrived soaked to the skin. (4) Run-on. Reading aloud helps you hear your own mistakes; it also slows you down enough to catch them.

Make it a habit

When you proofread, read your writing aloud at a natural pace. Mark every place where your voice drops and you would pause to breathe.

At each one there should be a full stop, a semicolon, or a comma with a joining word. If there is nothing, you have found a run-on.

Then choose the join on purpose:

• Full stop when the two ideas are separate.
• Semicolon when they are closely linked.
• Comma + and, but or so when you want to show the link.

Practise using because, while and although too. They turn two flat clauses into one well-shaped sentence.

Where students get stuck, and how we help

Students usually fuse sentences when they write fast and the ideas keep coming. In our English as a Second Language lessons, a teacher marks each run-on in your own work and coaches the read-aloud habit until boundaries come naturally.

Lessons start from RM70/hr. You can book a paid one-hour trial to try it.

Next step

Build your checking routine in the practice area. Then read about comma splices and sentence fragments. Use the proofreading guide on your next essay.

Next, visit our original practice tasks to use the rule in your own writing. Our IGCSE English tuition page explains how lessons run. When you are ready, the paid one-hour trial is the first step.