How do you fix sentence-boundary errors (fragments, run-ons, comma splices) and use commas, semicolons, and apostrophes correctly?
Sentence boundaries and punctuation: recognizing and fixing fragments, run-ons, and comma splices, and applying the core punctuation rules STAAR tests, commas in compound sentences and lists, semicolons between independent clauses, and apostrophes for possession and contraction.
How to fix sentence-boundary errors and punctuation on STAAR English I: fragments, run-ons, and comma splices, plus commas in compound sentences and lists, semicolons between independent clauses, and apostrophes for possession and contraction. The same conventions are scored on the ECR.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this skill is asking
Sentence-boundary errors (fragments, run-ons, and comma splices) and punctuation errors are a core part of STAAR English I editing, and the same conventions are scored on the ECR's Use of Conventions trait. The skill is recognizing when a sentence is incomplete or two sentences are wrongly joined, and applying the punctuation rules STAAR tests: commas, semicolons, and apostrophes. This page covers fixing fragments, run-ons, and comma splices, and the core comma, semicolon, and apostrophe rules. The transferable skill is hearing where one complete thought ends and the next begins, and punctuating the join correctly, in editing questions and in your own writing.
Sentence boundaries: fragments, run-ons, and comma splices
The boundary errors are the most-tested punctuation issue.
The test for these errors is to ask whether each side of a join could stand alone as a sentence. If both sides are complete, they need real separation (period, semicolon, or comma-plus-conjunction); a lone comma is a splice and no punctuation is a run-on. If one side cannot stand alone, joining it to the other with the right link fixes a fragment.
Commas, semicolons, and apostrophes
A few punctuation rules cover most STAAR questions.
The apostrophe rule trips many students because of the "its/it's" and plural-possessive cases. Remember: "it's" always means "it is" or "it has"; the possessive "its" has no apostrophe. For possession, decide whether the owner is singular (add 's) or plural ending in s (add only the apostrophe). A plain plural never takes an apostrophe.
Punctuating under time pressure
Try this
Q1. What are the three ways to fix a run-on or comma splice? [Recall]
- Cue. A period (make two sentences), a semicolon, or a comma plus a coordinating conjunction (for, and, nor, but, or, yet, so). Each properly separates two independent clauses.
Q2. Is "The students' projects were on display" punctuated correctly if there are many students, and why? [Short explanation]
- Cue. Yes. "Students'" is plural possessive: the projects belong to multiple students, so the apostrophe goes after the s. Plural nouns ending in s show possession with a trailing apostrophe, not 's.
Exam-style practice questions
Practice questions written in the style of TEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
STAAR English I (editing, style)1 marksWhich is a complete, correctly punctuated sentence? (1) The team practiced hard, they won the game. (2) The team practiced hard they won the game. (3) The team practiced hard, so they won the game. (4) Because the team practiced hard.Show worked answer →
Answer: (3). Two independent clauses joined correctly need a comma plus a coordinating conjunction ("so"), a semicolon, or a period. Option (3) uses "comma plus so" correctly.
Why not the others: (1) is a comma splice (two independent clauses joined by only a comma); (2) is a run-on (no punctuation between clauses); (4) is a fragment (a dependent clause with no main clause). Recognizing fragments, run-ons, and comma splices is core to STAAR editing.
STAAR English I (editing, style)1 marksWhich sentence uses the apostrophe correctly? (1) The dogs bowl was empty. (2) The dog's bowl was empty. (3) The dogs' bowl was empty for one dog. (4) The dogs bowl's was empty.Show worked answer →
Answer: (2). An apostrophe before the "s" shows singular possession: one dog's bowl. The bowl belongs to one dog, so "dog's" is correct.
Why not the others: (1) omits the apostrophe needed for possession; (3) "dogs'" is plural possessive (more than one dog), which contradicts "one dog"; (4) misplaces the apostrophe on "bowl." Apostrophes mark possession (singular before the s, plural after) or contraction, never a simple plural.
Related dot points
- Revising for clarity and organization: improving a draft's meaning rather than its mechanics, adding or sharpening a supporting detail, reordering sentences for logical flow, choosing effective transitions, and deciding whether a sentence belongs, the focus of STAAR revising questions.
How to revise a draft on STAAR English I: improving clarity, development, and organization rather than mechanics, adding a supporting detail, reordering for flow, choosing transitions, and deciding whether a sentence belongs. STAAR revising questions are multiple choice on a student draft.
- Editing for grammar and usage: identifying and correcting the grammar and usage errors STAAR tests, subject-verb agreement, pronoun-antecedent agreement and pronoun case, verb tense consistency, and misplaced or dangling modifiers, in a student draft and in your own writing.
How to edit for grammar and usage on STAAR English I: subject-verb agreement, pronoun-antecedent agreement and case, verb-tense consistency, and misplaced or dangling modifiers. STAAR editing questions are multiple choice on a student draft, and the same conventions are scored on the ECR.
- Word choice and precision: choosing the most precise and appropriate word for the context, tightening vague or wordy phrasing, maintaining a consistent and appropriate tone, and correcting commonly confused words (their/there/they're, affect/effect, than/then) in a STAAR draft.
How to choose precise words on STAAR English I: selecting the most precise and appropriate word for the context, tightening vague or wordy phrasing, keeping a consistent tone, and correcting commonly confused words. STAAR tests word choice in revising questions, and precise diction strengthens the ECR.
- The revising and editing question types: how STAAR presents revising and editing as multiple-choice questions on a student draft, how to read the prompt to tell a revising task (meaning, organization) from an editing task (grammar, mechanics), and how the new item formats apply to these questions.
How STAAR English I presents revising and editing questions: multiple choice on a student draft, telling a revising task (meaning, organization) from an editing task (grammar, mechanics) by reading the prompt, and how the redesigned item formats apply. Knowing the question type tells you which fix to make.
- The ECR rubric and scoring: how the 5-point analytic rubric works (Development of Ideas 0 to 3, Use of Conventions 0 to 2), what each trait rewards, the rule that a 0 on ideas forces a 0 on conventions, and how to write toward the top score on each trait.
How the STAAR English I extended constructed response is scored: the 5-point analytic rubric, Development of Ideas (0 to 3) and Use of Conventions (0 to 2), the rule that a 0 on ideas zeroes conventions, and how to write toward the top of each trait. Learning the rubric is the highest-leverage essay skill.
Sources & how we know this
- STAAR Reading Language Arts Resources — TEA (2025)
- Texas Essential Knowledge and Skills for English Language Arts and Reading — TEA (2017)