The writing section of the TOEFL test is one of the most challenging parts for many students. While ideas and structure matter, grammar and vocabulary play a crucial role in determining your final score. Even strong candidates often lose marks due to avoidable language mistakes. Understanding these common errors can help you improve accuracy and boost your performance in the TOEFL writing section.
If you’re preparing seriously, remember that The Princeton Review Singapore provides TOEFL classes, offering expert guidance to refine both grammar and vocabulary skills.
Why Grammar and Vocabulary Matter
In the TOEFL, your writing is evaluated based on clarity, coherence, and language accuracy. Examiners look for:
- Correct grammar usage
- Appropriate vocabulary
- Clear sentence structure
Errors in these areas can make your essay difficult to understand, even if your ideas are strong.
Common Grammar Errors in TOEFL Writing
1. Subject-Verb Agreement Mistakes
One of the most frequent errors is incorrect subject-verb agreement.
Example:
- Incorrect: People is concerned about climate change.
- Correct: People are concerned about climate change.
Always ensure that your verb matches the subject in number.
2. Incorrect Tense Usage
Using the wrong tense can confuse the reader and weaken your argument.
Example:
- Incorrect: Yesterday, the government implement a new policy.
- Correct: Yesterday, the government implemented a new policy.
Be consistent with your tenses, especially when describing past or hypothetical situations.
3. Run-On Sentences and Fragments
Many students write overly long sentences or incomplete thoughts.
Run-on example:
The internet is useful it helps students learn faster.
Correct version:
The internet is useful because it helps students learn faster.
Clear sentence boundaries improve readability.
4. Misuse of Articles (a, an, the)
Articles are often confusing for non-native speakers.
Example:
- Incorrect: She is best student in class.
- Correct: She is the best student in the class.
Using articles correctly makes your writing sound more natural.
5. Preposition Errors
Incorrect prepositions can change the meaning of a sentence.
Example:
- Incorrect: He is interested on science.
- Correct: He is interested in science.
These small mistakes can affect your overall score.

Common Vocabulary Errors in TOEFL Writing
1. Using Words Incorrectly
Many students try to use advanced vocabulary but end up misusing it.
Example:
- Incorrect: This solution is very sensitive to the problem.
- Correct: This solution is very effective for the problem.
Always ensure you understand the meaning and context of words.
2. Overusing Simple Vocabulary
Using basic words repeatedly can lower the quality of your essay.
Example:
- Repetitive: Good, very good, really good
Instead, use varied vocabulary like beneficial, effective, and advantageous.
3. Awkward Word Combinations
Some phrases may be grammatically correct but sound unnatural.
Example:
- Incorrect: Make a homework
- Correct: Do homework
Learning common collocations improves fluency.
4. Lack of Variety
Repeating the same words throughout your essay makes it less engaging. Try to use synonyms where appropriate to enhance your writing.
TOEFL vs IELTS Writing: A Quick Note
When comparing TOEFL vs IELTS, both exams assess writing skills but in slightly different ways. TOEFL focuses more on structured, academic responses, while IELTS may include more varied task types. However, in both tests, grammar and vocabulary accuracy are equally important.
How to Avoid These Errors
1. Practice Regularly
Consistent practice is key. Write essays regularly and review your mistakes.
2. Get Feedback
Having your writing evaluated by experts can help identify hidden errors and improve your skills faster.
3. Build Strong Foundations
Focus on mastering basic grammar rules before attempting advanced structures.
4. Learn Vocabulary in Context
Instead of memorizing word lists, learn how words are used in sentences.
5. Review Sample Essays
Analyzing high-scoring essays can give you insights into proper grammar usage and vocabulary.
Final Thoughts
Improving your grammar and vocabulary is essential for success in the TOEFL test. By identifying and correcting common errors, you can significantly enhance the quality of your writing.
Whether you’re just starting your preparation or refining your skills, consistent effort and the right guidance will help you achieve your desired score. Focus on clarity, accuracy, and variety, and you’ll be well on your way to excelling in the TOEFL writing section.