By 3rd grade, most students already know the basics of writing complete sentences and using punctuation. But grammar is still a challenge — especially as children start writing longer sentences and using new word types.
Here are some of the most common grammar mistakes 3rd graders make, along with easy ways to help them improve.
1. Confusing Plural and Singular Forms
Many students struggle with irregular plural nouns like children, mice, or teeth.
They often add -s or -es by default — writing childs instead of children, for example.
🧩 How to fix it:
Practice through repetition and examples. Create short matching games or review worksheets that highlight the difference between regular and irregular forms.
👉 Try the Irregular Plural Nouns Worksheets for structured practice.
2. Misusing Verb Tenses
Switching between past and present tense in the same paragraph is a very common 3rd-grade issue.
For example: “Yesterday I go to the park and play.”
🧩 How to fix it:
Start by reviewing irregular verbs separately — focusing on past forms like went, had, saw, and did. Then have students identify verbs in short texts and correct them.
👉 Use the Irregular Verbs Worksheets to reinforce correct usage.
3. Confusing Adjectives and Adverbs
It’s easy for students to mix up words like quick and quickly or happy and happily.
They might say “She runs quick” instead of “She runs quickly.”
🧩 How to fix it:
Highlight that adjectives describe nouns and adverbs describe verbs. Short comparison activities work well — for example, underlining the describing word in a sentence.
👉 The Adjectives Worksheets section includes printable activities for this exact topic.
4. Mixing Up Pronouns
In 3rd grade, students start using pronouns more frequently — but not always correctly.
They may replace nouns in a sentence incorrectly, such as “Her is playing” or “Them went home.”
🧩 How to fix it:
Focus on subject vs. object pronouns with short fill-in-the-blank exercises. Encourage students to read sentences aloud — hearing the mistake often helps them catch it.
👉 Check out Pronouns Worksheets for 3rd Grade to practice.
5. Forgetting Capitalization and Punctuation
Even strong readers forget to capitalize I or the first word of a sentence. Punctuation like commas and quotation marks also get overlooked.
🧩 How to fix it:
Have students review their writing with a checklist before submitting. Focus on one rule at a time — for instance, only capitalization in one session, punctuation in the next.
👉 You can combine this with Reading Comprehension Worksheets (3rd Grade) so they learn to recognize punctuation and sentence structure in context.
Key Takeaway
Grammar at this level isn’t about memorizing every rule — it’s about noticing patterns and practicing consistently.
Short, focused exercises and reading aloud regularly can make a huge difference.
For ready-to-use practice materials, explore: