Common Mistakes in Language Arts

Why learn common mistakes?

Every writer makes mistakes, even professional authors. The difference is that good writers know which mistakes to look for. When you learn the most common errors, you can catch them during proofreading and make your writing clear and easy to read.

This guide covers the mistakes that show up most often in student writing, with a quick fix for each one.

Sentence mistakes

Fragments

A fragment is an incomplete sentence. It is missing a subject, a verb or a complete thought.

• ✗ Went to the park after school. (Who went?)
• ✗ Because the dog was barking. (What happened?)
• ✓ My brother went to the park after school.
• ✓ I couldn’t sleep because the dog was barking.

Run-on sentences

A run-on sentence joins two complete sentences without the right punctuation.

• ✗ I love pizza it is my favourite food.
• ✗ I love pizza, it is my favourite food. (A comma alone is not enough. This is called a comma splice.)

Fix it in one of three ways:

• Use a period: I love pizza. It is my favourite food.
• Use a comma and a joining word: I love pizza, and it is my favourite food.
• Use a semicolon: I love pizza; it is my favourite food.

Grammar mistakes

Subject-verb agreement

Subject-verb agreement means the subject and the verb must match.

• ✗ The dogs runs fast. → ✓ The dogs run fast.
• ✗ She don’t like peas. → ✓ She doesn’t like peas.
• ✗ The box of crayons are on the desk. → ✓ The box of crayons is on the desk. (The subject is box, not crayons.)

Mixing verb tenses

Keep your verb tense the same unless the time really changes.

• ✗ Yesterday I walk to the store and bought milk.
• ✓ Yesterday I walked to the store and bought milk.

Pronoun mistakes

• ✗ Me and Sam went swimming. → ✓ Sam and I went swimming.
• ✗ Give it to Sam and I. → ✓ Give it to Sam and me.

Trick: Remove the other person. You would say I went swimming and Give it to me.

Double negatives

• ✗ I don’t have no homework. → ✓ I don’t have any homework. or I have no homework.

Word mistakes

Homophones

A homophone sounds like another word but has a different meaning and spelling. These are the most common mix-ups.

Commonly confused pairs

• lose (misplace) vs loose (not tight)
• affect (verb: to change) vs effect (noun: a result)
• a lot is two words, never alot

Punctuation mistakes

Apostrophes

An apostrophe has two jobs: contractions (don’t, I’m) and ownership (Mia’s bike).

• ✗ The apple’s are red. → ✓ The apples are red. (Plurals don’t need apostrophes.)
• ✗ The dogs bone. → ✓ The dog’s bone.

Capital letters

Capitalize the first word of a sentence, the word I, and names of people, places, days and months.

• ✗ on monday, i visited toronto. → ✓ On Monday, I visited Toronto.

Missing commas

Use commas in lists and after introductory words.

• ✓ We packed sandwiches, apples, and juice.
• ✓ After dinner, we played cards.

A proofreading checklist

When you finish writing, read your work slowly, out loud if you can. Check:

1. Does every sentence have a subject and a verb?
2. Did I join sentences correctly?
3. Do my subjects and verbs agree?
4. Did I keep the same tense?
5. Did I choose the right homophones?
6. Are capitals and end punctuation in place?
7. Are apostrophes only in contractions and possessives?

Reading backwards, one sentence at a time, also helps you notice mistakes your brain might skip.

Try it yourself

Fix the mistakes in this paragraph:

me and my freind goes to the libary on saturday. their is alot of books there. we found a book about sharks it was really cool

One answer: My friend and I go to the library on Saturday. There are a lot of books there. We found a book about sharks. It was really cool.

Quick recap

• Fragments are incomplete; run-ons join sentences without the right punctuation.
• Subjects and verbs must agree, and tenses should stay consistent.
• Homophones like their, there and they’re are easy to mix up.
• Apostrophes are for contractions and ownership, not plurals.
• Always proofread with a checklist.