Run-On Sentences Worksheet

Lesson Overview

About this worksheet

A run-on sentence is two complete sentences that have been smashed together with no punctuation between them, or with only a comma (called a comma splice). Run-ons are one of the most common revision targets in elementary writing – students naturally produce them when they string ideas together with and, and, and. This worksheet gives third through fifth graders direct practice spotting the pattern and fixing it the simple way: split the run-on into two complete sentences with a period.

Section A on page 1 gives students 12 short sentences in a single-column list. The student labels each one correct or run-on. The mix alternates clean simple sentences (Maya painted a sunset; Three squirrels chased each other up the oak tree) with the three most common run-on patterns: no-punctuation runs (The bell rang the students ran outside), comma splices (We hiked all morning, we were tired by lunch), and contrasting comma-splice traps (The pizza was hot, so we let it cool – which is actually correct because of the conjunction).

Section B on page 2 raises the difficulty: each of 6 items is a run-on, and the student rewrites it as two separate sentences in a generous work box. The answer key gives a sample split for each item; any correct fix – two sentences with proper end punctuation – earns credit.

Page 3 is a complete answer key. The Section A list gives the one-word label; Section B gives a sample split version of each run-on. The reference box at the top of page 1 introduces the run-on pattern and shows two fix strategies (split with a period, or join with a comma plus a coordinating conjunction).

How to Use This Lesson

Read the reference box aloud and slow down on the two fix strategies – split with a period, or join with a comma plus and/but/or/so. Use the dog-ran-fast example to show why a comma alone is not enough.

Work Section A item 1 together: Maya painted a sunset has one subject and one verb, so it is a correct simple sentence. Item 2 (The bell rang the students ran outside) has two complete sentences crammed together with no punctuation, so it is a run-on.

Assign the rest of Section A independently or in pairs. Remind students that the comma-splice items (where two sentences are joined by only a comma) also count as run-ons.

Demonstrate Section B item 13 together: The puppy barked at the mailman it would not stop. Split with a period after mailman: The puppy barked at the mailman. It would not stop. Show that capital It is required because it starts a new sentence.

Use the answer key on page 3 for self-check or aide spot-check; remind students any correct fix counts.

Pair with the Complete Sentences Worksheet or the Sentence Fragments Worksheet for additional sentence-structure practice.

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