Lesson Plan: Correcting Sentence Fragments and Run-on Sentences

Page content

A Rare Disease

I saw Bob Pitchfield last Spring. He looked emaciated, face drawn in, eyes sunk. I asked him what was wrong.

He answered, “Because students can’t write in complete sentences.”

“What?” I replied.

“I’m going home, tomorrow will be better, where are my pills?”

“Come again, Bob”

“Why they use fragments and run-ons.”

I found out later that Bob had a rare disease, called Ireadtomanyhorribbleessayswithrunonsandfragmentitas, occurring only in high school English teachers. Luckily, there’s a cure: this sentence fragments and run-on sentences lesson plan. Use it now before you end up like Bob.

Common Fragments

A critical component of avoiding sentence fragments and run-on sentences is understanding what a correct sentence is and the different types of clauses that make up sentences (see previous lesson plan in the series for a run-down of clause types). Sentences must have at least one subject and one verb and express a complete thought. A sentence fragment is part of a sentence that is punctuated as if it were a complete sentence. They appear in the following forms:

Freestanding Subject or Verb:

Fragment: My dog, Rover.

Corrected: My dog, Rover, eats mice.

Subordinate Clause:

Fragment: Before I lost weight.

Corrected: Before I lost weight, I broke the trampoline three times.

A Phrase:

Fragment: Encouraging vagabond behavior.

Corrected: I was arrested for encouraging vagabond behavior.

Common Run-ons

A run-on sentence is two or more complete sentences incorrectly written as one. The most common is called a comma splice, in which two sentences are separated by a comma. Run-on sentences can be corrected in the following ways:

Separate the two sentences with a period:

Run-on: A couple wanted to go green this holiday, they saved the planet.

Corrected: A couple wanted to go green this holiday. They saved the planet.

Join them with a comma and a conjunction:

Corrected: A couple wanted to go green this holiday, and they saved the planet.

Join them with a semi-colon:

Corrected: A couple wanted to go green this holiday; they saved the planet.

Join them with a semi-colon and a conjunctive adverb:

Corrected: A couple wanted to go green this holiday; consequently, they saved the planet.


  • Post the above information in a noticeable location.

  • Have students take notes on it. I recommend Cornell Notes.

  • Instruct students to pick out a piece of writing. Circle any potential sentence fragment or run-on sentence.

  • Correct fragments by making sure they have a subject and a verb, and express a complete thought (you may want to review clauses).

  • Correct run-ons using the aforementioned strategies.

For practice connecting independent clauses correctly, the following activity works well:

  • Choose a topic of interest for students.

  • Instruct students to write 2 of each of the following types of sentences:

    • two independent clauses connected by a comma and a conjunction.
    • two independent clauses separated by a semi colon.
    • two independent clauses separated by a semi colon and a conjunctive adverb.

This post is part of the series: Better Grammar Equals Better Writing

Grammar builds the foundation for good writing: the better the grammar, the better the writing.

  1. Teaching Students How to Combine Sentences and Improve their Writing
  2. Lesson Plan: Eliminate Weak Verb-Adverb Combinations
  3. Lesson Plan: Eliminate “To Be” Verbs
  4. Lesson Plan: Write With Strong Verbs
  5. Lesson Plan: Active Voice vs. Passive Voice
  6. Revising Pronouns and Antecedents with this Lesson Plan
  7. Pronoun-Antecedent Agreement Made Easy
  8. Lesson Plan: Understanding Independent and Dependent Clauses
  9. Teach Your Kids to Eliminate Fragments and Run-ons in Their Writing
  10. Lesson Plan: Use Parts of Speech to Improve Sentence Beginnings