Dealing with sentence-level errors: The value of distinguishing error types

Daniel Emery

Sentence-level errors present a particular challenge for instructors who use writing in their courses. On the one hand, some sentence-level errors are easy to ignore when the meaning of a sentence is unimpeded. If the student understands the commutative property, the Council of Trent, or Ohm’s law, does it matter if they misplace a comma? On the other, the expectation of a particular variety of error-free prose is common enough in school and work settings that a failure to comment can shortchange our students and leave them unprepared for real-world demands. We may ask ourselves, can we allow a student to graduate with a major in mathematics, history, or electrical engineering who “still” makes errors with commas?

Error has been an obsession of teachers of writing and teachers who use writing for as long as writing has existed as a technology. Yet, as the late Joseph Williams remarked in 1981’s “The Phenomenology of Error,”

Joseph Williams
Joseph Williams

“I am puzzled why some errors should excite…fury, while others, not obviously different in kind, seem to excite only moderate disapproval. And I am puzzled why some of us can regard a particular item as a more or less serious error, while others, equally perceptive, and acknowledging that the same item may be in some sense an “error” seem to invest in their observation no emotion at all.” (152) 

More recently, scholars like Nancy Effinger Wilson have noted that some errors that seem to invite emotional response might reveal biases regarding language use. This tip cannot solve these dilemmas or quiet the angry reactions, but it instead offers two important considerations for addressing sentence-level errors in writing.

Is it a simple mistake or is it an error?

In their discussion of formative assessment for writing improvement, Frey and Fisher (2013) distinguish between mistakes and errors. Mistakes are those lapses in writing that might result from an oversight or misstatement. When writers are made aware of mistakes, they understand an appropriate response to the lapse, are aware of the “next step” to remedy it, and can make changes with little additional instruction. Errors, by contrast, are those mistakes where a writer fails to recognize a lapse even when an instructor calls attention to it, or when a writer recognizes a lapse but is unable to offer a correction.

Proofreading text with red pencil

The important distinction here is that the difference between mistakes and errors is not what appears on the page, but rather how the writer responds when a lapse is made apparent. A writer who joins two independent clauses with a comma might correct it (through subordination, conjunction, or a change in punctuation) and might even be able to diagnose the error as a comma splice.[i] If a writer is unable to recognize the error caused by uniting two independent clauses, they may benefit from instruction on uniting clauses or punctuation.

The best way for an instructor to know if a particular lapse is a mistake or an error is to note the presence of a lapse with a mark next to the line and ask students to identify and correct their own errors, a practice known as “minimal marking.” Research from Richard Haswell and others suggests that most errors are mistakes, and students should be able to identify and diagnose their own errors with a minimal mark.

Not all sentence-level problems are grammatical errors

While many experienced readers and writers can identify sentences that seem awkward or sound “off,” we may not be able to identify the precise source or type of error in a sentence. While some issues like subject-verb agreement or sentence fragments might be apparent to experienced readers, issues like faulty parallelism (style); unnecessary, incorrect, or missing dashes (punctuation); or the confusion of adjectival and adverbial forms of a word (usage) may be harder to identify. Worse, even some obvious errors, like word choice or an incorrect preposition might be easy to identify for an expert, but difficult to explain beyond “That’s just the way it is.”

Not all instructors who use writing need to be professional grammarians! Simply noting the presence of a sentence that seems “off” and asking a writer for clarification can be enough to encourage revision. Further, students who are invited to account for their own errors may become better at identifying patterns of error in their own writing and more effective in making choices about revision. Just as errors have multiple sources, many errors can be corrected in multiple ways. Asking students to revise their own writing can help them build a repertoire of effective revision strategies.


Effinger Wilson, Nancy. “Bias in the writing center” in Writing Centers and the New Racism

Ferris, Dana. The Treatment of Error in Second Language Writing.
Fisher Saller, Carol. The Subversive Copy Editor.
Frey, Nancy, and Douglas Fisher, The Formative Assessment Action Plan.

Further Support

Visit Teaching with Writing on the Center for Writing website for additional resources. As many of you know, our WAC program also hosts the popular Teaching with Writing event series.

Register now for our TWW panel on Writing and Interpretation (March 23) and the 2018 WEC Symposium (April 20).

[i] According to Lunsford and Lunsford’s “‘Mistakes are a fact of life’: A national comparative study,” “comma splice” was the second most frequently occurring error in their national study of student writing. Interestingly, the comma splice was only the 14th most likely error for instructors to mark or comment.


Good tip, Dan! What I take from it is a reminder that we instructors and readers are in a position to help by detecting garbled or otherwise unclear passages and by engaging students in a process of diagnosis and remedy.. I'm glad also for the suggestion that we question possible causes for our emotional reactions to the writing problems we see, Might our mild outrage or sense of affront stem from our own past experiences with teachers and editors? Are there elements of inadvertent class-related judgement? We might be served by asking ourselves how we can best persuade those we teach that their ideas are worthy of clear transmission. Thanks!