5 Grammar Mistakes That Hurt Your Grade

Grammar Mistakes That Cost You Points: What Students Need to Watch For

Whether it's a short answer question, a book report, or the essay portion of the SAT, grammar matters more than many students realize. Even the most insightful writing can lose points if it's riddled with grammar errors. The good news? Most of these mistakes are easy to fix once you know what to look for.

Let’s break down the most common grammar slip-ups that cost students points and how to avoid them.

1. Subject-Verb Agreement Errors

This is one of the most frequent issues students face.

The Rule: The subject and verb must agree in number. If the subject is singular, the verb must be singular. If the subject is plural, the verb must be plural.

Wrong: The dogs runs fast.
Right: The dogs run fast.

Tip: Ignore the words between the subject and verb. Focus on matching the subject with the correct verb form.

2. Misplaced or Dangling Modifiers

Modifiers describe something in the sentence. When they’re in the wrong place, the sentence becomes confusing or funny.

Wrong: Running down the street, the backpack fell off.
(This makes it sound like the backpack was running.)

Right: Running down the street, I dropped my backpack.

Tip: Always place modifiers next to the word they are describing.

3. Comma Confusion

Commas can be tricky—but they’re important. Using them incorrectly can completely change the meaning of a sentence.

Common Mistakes:

• Missing commas in a list:
  I like cooking my family and my dog. → Yikes!
  I like cooking, my family, and my dog. → Much better.

• Run-on sentences:
  I finished my homework it was easy.
  → Needs a comma and a conjunction: I finished my homework, and it was easy.

Tip: Read your sentences aloud. If you naturally pause, a comma might be needed.

4. Its vs. It’s (and Other Tricky Homophones)

These commonly confused words can hurt your writing even if the rest of your essay is great.

• It’s = It is

• Its = Possessive (belonging to it)

• Their / There / They’re

• Your / You’re

Wrong: Its a great day to study grammar.
Right: It’s a great day to study grammar.

Tip: If you can replace the word with "it is" and it still makes sense, use it’s.

5. Sentence Fragments

Every sentence needs a subject and a verb. A sentence fragment is an incomplete thought.

Wrong: Because I studied all night.
Right: I passed the test because I studied all night.

Tip: If a sentence starts with a word like because, when, or although, make sure it’s part of a complete idea.

Why It Matters

Even one or two grammar mistakes can lower your grade or test score. Teachers and exam scorers are trained to look for clarity, structure, and proper grammar. Clean writing shows you're not only smart you’re also careful, which matters in college and beyond.

Final Takeaway

If you want to improve fast, focus on one grammar mistake at a time. Review your old essays or writing assignments and spot where you’ve made these errors. You’ll be surprised how quickly your writing will improve once you’re aware of the patterns.