Who, Which, and That: Relative Clauses for English Learners

Relative clauses help you add information without writing many short sentences. But many learners feel confused about who which that grammar because the words look similar. The simple starting point is this: use “who” for people, “which” for things or animals in many cases, and “that” for people or things in defining clauses.

For example, “The teacher who helped me was patient” is correct because the teacher is a person. “The book which I bought yesterday is useful” is correct because the book is a thing. “The course that I joined last month was helpful” is also possible because “that” can refer to a thing in this type of clause.

Use relative clauses to combine ideas

Instead of writing “I met a teacher. The teacher helped me,” you can write: “I met a teacher who helped me.” This sounds smoother and more natural. Relative clauses are useful in IELTS Writing, emails, workplace English, and everyday storytelling.

The relative word connects the noun to extra information. In “The student who asked the question was nervous,” the clause “who asked the question” tells us which student. Without it, the listener may ask, “Which student?”

This is called a defining relative clause because it identifies the person or thing. In this kind of sentence, the information is necessary. The sentence is not just adding decoration; it is helping the reader understand exactly who or what you mean.

Choosing who, which, and that

Use “who” when you are talking about people: “The man who called you is my uncle.” “The students who submitted the task received feedback.” This is usually the safest choice for people.

Use “which” for things or animals when you want a clear standard form: “The phone which I bought is expensive.” “The article which we read was difficult.” In everyday English, many people use “that” instead of “which” in defining clauses, so “The phone that I bought is expensive” is also natural.

Use “that” for people or things in defining clauses, especially in spoken and simple written English: “The teacher that explained the rule was very clear.” However, in formal writing, “who” often sounds better for people.

For the quiz sentence, “The teacher ___ helped me was patient,” the best answer is “who”. “Which” does not fit because the teacher is a person. “Where” refers to place, not a person.

Common mistakes Bangla speakers make

One common mistake is using “where” for everything. For example, “The person where helped me” is incorrect. Use “where” for places: “The school where I studied was small.” For people, use “who”.

Another mistake is repeating the noun or pronoun. “The teacher who he helped me” is incorrect because “who” already refers to the teacher. Write: “The teacher who helped me.” Similarly, do not write “The book which I bought it.” Write: “The book which I bought.”

Learners also sometimes avoid relative clauses completely and write many short sentences. Short sentences are not always wrong, but too many of them can make writing sound basic. Relative clauses help you connect ideas more maturely.

Practise sentence combining

Take two short sentences and combine them:

• “I know a student. He studies at night.” → “I know a student who studies at night.”
• “She bought a laptop. It was very expensive.” → “She bought a laptop which was very expensive.”
• “This is the video. I watched it yesterday.” → “This is the video that I watched yesterday.”

For more English grammar practice, you can explore the Related Fluento Guide. Start with simple sentences first. Once the pattern feels natural, use relative clauses in IELTS examples, emails, and spoken answers. The goal is not to make every sentence longer. The goal is to add useful information clearly.