Typical writing errors in school work and how to fix them
Recurring writing problems in school assignments, including unclear sentences, unsupported claims and small grammar slips, with checks, proofreading habits and a personal error log.
Teachers often mark the same few problems across very different assignments because the causes repeat: sentences that leave the reader guessing, claims that arrive without support, and small mechanical slips that a careful proofread would catch. The fixes repeat too, which means a student who learns to recognize these patterns can improve many assignments at once rather than fixing each one separately.
A short, repeatable check on your own draft catches most of these problems faster than a general resolve to write more carefully.
Unclear sentences
The most frequent problem is a sentence that makes sense to its writer but not to a reader who has never seen the notes. Pronouns such as "this," "it" and "they" are often the cause. When a sentence begins with "This shows that...," ask what "this" refers to. If the answer is a whole paragraph, name the thing directly, for example "This result suggests that..." followed by the result itself.
A second source of unclear writing is packing several ideas into one sentence. A sentence that contains a cause, an effect, an example and an opinion is hard to follow even when each piece is correct. Read each sentence and ask whether it has one main idea. If it does not, divide it at the point where the subject changes, and give each part its own sentence.
Claims without evidence
Teachers often write "Where is your evidence?" in the margin for a reason. A claim such as "The character changes her mind because she is afraid" needs a passage, fact or example that supports it. In literature, quote the phrase you are relying on and show how it supports the claim. In science and history, cite the measurement, date or source that backs the statement.
Another frequent gap is evidence that is present but never explained. A quotation or statistic sitting in a paragraph does not do the work on its own. After each piece of evidence, add one or two sentences that explain how it supports the point. A practical test is to ask, for every sentence of evidence, "Why does this matter for my claim?" If the answer is not written down, the reader has to guess.
Mechanical errors that repeat
Some errors appear in nearly every class. The table lists a few that teachers mark most often, along with a quick check for each.
Scroll sideways to see the full table →
| Error | Example | Quick check |
|---|---|---|
| Its and it's | "The team lost it's captain" | "It's" means "it is." If "it is" fits the sentence, keep the apostrophe; otherwise use "its." |
| Their, there and they're | "There plan was clear" | Read the sentence with "they are" in place of the word. If the meaning breaks, choose "their" or "there" to fit. |
| Subject and verb agreement | "The results of the test was low" | Find the true subject. Here it is "results," a plural, so the verb should be "were." |
| Shifting tenses | "She walks home and then ate dinner" | Keep one tense for the events you describe unless you are clearly signaling a change in time. |
The shifting-tenses example is wrong because it moves from present to past within one sentence, not because of the tense it uses. In literature analysis, the present tense is the usual convention, so describing what happens in a novel as "she walks home" is typical. The fix is to keep one tense across the sentence, such as "She walks home and then eats dinner."
Each of these errors has a check that takes seconds. The problem is rarely a lack of knowledge about the rule. It is that the writer did not look for the error in the final draft.
Proofreading habits that catch errors
Proofreading works best as a separate step from drafting. While you are writing, your attention is on the content, so small errors slip past. If possible, leave the draft for a few hours or until the next day, and then read it with a different purpose. Proofreading once at the very end, while also trying to refine the argument, usually catches less than two focused passes: one for meaning and one for mechanics.
Reading aloud is one of the most reliable techniques, because the ear notices missing words, repeated words and awkward rhythm that the eye skips. Reading the sentences in reverse order, last sentence first, is another way to catch spelling errors, since it removes the flow that hides them. Many students also find that printing the draft helps, because mistakes are easier to spot on paper than on a screen.
Keeping a personal error log
The most efficient long-term fix is a short error log. When an assignment comes back, write down the three problems the teacher marked most often, with one example from your own sentences. Over several assignments the list reveals patterns. A student who finds that most of their lost points come from unsupported claims knows to focus on evidence, not on punctuation.
Review the log before you start the next assignment and check your draft against it. If a comment is unclear, ask the teacher what it means in that subject, such as what "weak support" looks like in a history essay. Teachers can often point to the specific sentence or paragraph where the problem appears, which turns a general comment into a concrete habit you can practice.