‘That’ Grammar Rules

Written by Dan

Last updated

Are your students having trouble understanding the correct use of ‘that’ in their writing? Are they unsure when to use ‘which’, or even why these little words are so important?

It’s time to brush up on the basic grammar rules and help your students become confident writers! In this blog post, we’ll go over all you need to know about using ‘that’ and other similar words correctly.

We’ll learn how to identify when it’s appropriate to use a ‘that’ clause when it’s better suited for something else like ‘which’, and how best to explain each rule in simple terms.

Get ready – let’s get started decoding the world of grammar!

Related: For more, check out our article on How To Use Speech Marks Correctly  here.

That vs Which

Understanding ‘That’

let’s dive right in and unravel the mystery of ‘that’ in grammar. Now, ‘that’ is a pretty versatile player in the English language, serving as a conjunction, a pronoun, or even a determiner depending on the context.

As a conjunction, ‘that’ is used to introduce a subordinate clause, for example: “I believe that you can do it.” Here, ‘that’ connects the main clause “I believe” with the subordinate clause “you can do it.

Now, when ‘that’ serves as a relative pronoun, it refers back to a noun or pronoun mentioned earlier, linking it to a following clause.

Let’s look at an example: “The book that you recommended was fantastic.” In this sentence, ‘that’ is referring back to ‘the book’ and linking it to the additional information ‘you recommended.

But wait, there’s more! ‘That’ also moonlights as a demonstrative determiner, pointing towards a specific item in a context.

For instance, in the sentence “That car is mine,” ‘that’ is used to point out a specific car being referred to.

So, as you can see, our little word ‘that’ wears many hats in the world of grammar. Understanding its various roles can help us construct clear and effective sentences.

Remember, practice makes perfect, so why not give these examples a go in your next piece of writing?

‘That’ versus ‘Which’

Just like ‘that’, ‘which’ is also a multifaceted term in the English language, functioning as both a relative pronoun and an interrogative word.

As a relative pronoun, ‘which’ introduces a non-defining or non-restrictive clause, providing additional information about something without necessarily specifying it.

For example: “The painting, which was quite expensive, was bought by a private collector.”

Here, ‘which’ introduces additional information about the painting, but this information isn’t essential to identify the painting.

Now, let’s look closer at ‘which’ versus ‘that’. Both ‘which’ and ‘that’ can introduce additional information in a sentence but are used in slightly different circumstances.

‘That’ is used for defining or restrictive clauses, which introduces information essential to identify what we’re talking about.

‘Which’, conversely, is used for non-defining or non-restrictive clauses, introducing additional, non-essential information.

So, when do we use ‘which’ instead of ‘that’? If you want to add some extra info about something, but the sentence makes sense even without this information, then ‘which’ is your go-to guy.

Let’s see it in action: “My car, which is blue, needs a wash.” The fact that the car is blue is extra information – the sentence would still make sense if we said “My car needs a wash.”

On the flip side, if the information is needed to understand what’s being referred to, then ‘that’ comes into play.

For example: “The dress that you wore yesterday was stunning.” Here, ‘that’ is needed to specify which particular dress we’re talking about.

Remember, the key to mastering ‘which’ versus ‘that’ lies in understanding whether the information is essential (use ‘that’) or just additional (use ‘which’). Keep practicing and soon you’ll be using ‘which’ and ‘that’ like a pro!

top 10 grammar rules

Explaining ‘That’ Rules Simply

Alright, let’s break down the rules of ‘that’ into bite-sized pieces. You know how sometimes grammar can seem like a labyrinth of confusion? Well, not today! We’re going to untangle ‘that’ and make it as easy as pie.

Rule number one: ‘That’ is a pro at introducing essential information. When you’ve got a piece of info that’s absolutely crucial to identifying what or whom you’re talking about, call on ‘that’.

Like in the sentence, “The cake that I baked this morning is chocolate.”

Here, ‘that’ introduces the essential detail ‘I baked this morning’, which tells us exactly which cake we’re talking about.

Rule number two: ‘That’ cannot be used with commas to offset nonessential information. If you have extra details that aren’t vital to your sentence, you’ll want to use ‘which’ instead, and set it off with commas.

For example, “My bike, which is red, has a flat tire.” Here, ‘which is red’ is an extra detail – the sentence would still make sense if we said, “My bike has a flat tire.”

Now, for some handy tips to remember these rules. Picture ‘that’ as a spotlight in a dark room, focusing on the important stuff and pushing everything else into the shadows.

Essential information, step into the light! On the other hand, imagine ‘which’ as a friendly tour guide, throwing in interesting tidbits here and there to enrich your journey. Nonessential info, come along for the ride!

Common Mistakes and How to Avoid Them

Ever played a game of ‘spot the mistake’ with grammar? Well, when it comes to using ‘that’, it’s a game many of us play unwittingly.

But don’t worry, we’re here to turn those common mistakes into learning opportunities. So let’s put on our detective caps and find out where ‘that’ often trips us up.

Perhaps the most common blunder is using ‘that’ when ‘who’ or ‘whom’ would be more appropriate. Remember, ‘who’ and ‘whom’ are used when referring to people, while ‘that’ is used for things.

For instance, saying “She’s the one that gave me the book” should really be “She’s the one who gave me the book.” Keep this in mind next time you’re writing about people.

Another frequent mix-up is using ‘that’ instead of ‘which’ in non-restrictive clauses. As we discussed earlier, ‘that’ is used for essential information, while ‘which’ is used for extra, nonessential details.

So saying “My car, that is red, needs a wash” should actually be “My car, which is red, needs a wash.”

So how do we avoid these little errors? Practice makes perfect, so the more you write, the better you’ll get at spotting these mistakes. A good strategy is to read your work aloud – sometimes, hearing the words can make it easier to catch mistakes.

Remember the ‘that’ spotlight and ‘which’ tour guide analogy? Keep that in mind as you write. If you’re introducing essential info, shine the ‘that’ spotlight on it. For additional details, let ‘which’ be your friendly tour guide.

And don’t forget about ‘who’ and ‘whom’ for people. Think of ‘who’ and ‘whom’ as your friends at a party – when you’re talking about people, they’re your go-to guys.


So, we’ve come to the end of our exciting exploration into the world of ‘that’. We’ve journeyed through its roles as a relative pronoun, its distinction from ‘which’, and its grammatical rules.

We’ve also looked at students’ common mistakes when using ‘that’ and how to avoid them.

Remember, ‘that’ is your trusty guide for introducing essential information. It’s like a spotlight, highlighting the crucial details in your sentences.

On the other hand, ‘which’ is your tour guide for nonessential, additional info. And don’t forget ‘who’ and ‘whom’ – they’re your friends when you’re talking about people.

But knowing the rules is just half the battle. The real challenge lies in applying them consistently in your writing. This is where practice comes into play.

The more you write, the more familiar you’ll become with these rules, and the easier it will be to avoid common mistakes.

Reading your work aloud can also help you catch errors and improve your writing skills.

So, why is all this important? Well, because grammar is the backbone of effective communication.

It ensures our messages are clear, accurate, and easy to understand. So, whether you’re penning an essay, crafting a social media post, or writing an email, using correct grammar can make all the difference.

And remember, it’s okay to make mistakes along the way – they’re stepping stones to learning and improvement. So, keep practising, stay positive, and don’t be afraid to embrace the wonderful world of grammar. You’ve got this!


What are the basic rules for using ‘that’ in a sentence?

‘That’ is commonly used as a conjunction to introduce a restrictive clause, or a clause that provides essential information about the noun it follows. It can also be used as a demonstrative pronoun to refer to something previously mentioned.

When should I use ‘that’ instead of ‘which’?

‘That’ is commonly used as a conjunction to introduce a restrictive clause, or a clause that provides essential information about the noun it follows. It can also be used as a demonstrative pronoun to refer to something previously mentioned.

Can ‘that’ be omitted from a sentence?

In some cases, ‘that’ can be omitted without changing the meaning of the sentence, especially in informal writing or speech. However, it’s often clearer to include it, particularly in more complex sentences.

Are there any exceptions to these ‘that’ grammar rules?

Like many grammar rules, there are exceptions. For instance, ‘that’ should not be used to introduce questions within sentences, and it’s not typically used to introduce non-restrictive clauses.

Why is it important to use ‘that’ correctly?

Using ‘that’ correctly helps to make your writing clear and precise. It ensures that your reader understands exactly what you’re referring to, and can help to avoid ambiguity.

How can I teach these rules to my students in a simple way?

Start with the basics: explain the difference between restrictive and non-restrictive clauses, and how ‘that’ and ‘which’ are used differently with each. Practice with examples, and encourage students to identify and correct incorrect uses of ‘that’.

What other words are similar to ‘that’ in their grammatical use?

Other words that work similarly to ‘that’ include ‘which’, ‘who’, and ‘whom’. These words are also used to introduce different types of clauses.

Are there differences in how ‘that’ is used in American and British English?

There can be some differences. For instance, British English often uses ‘which’ where American English would use ‘that’. However, the basic rules remain the same across both dialects.

Where can I find more resources to help my students understand the use of ‘that’?

There are many grammar textbooks and online resources that provide further explanations, examples, and exercises on the use of ‘that’ and other conjunctions and pronouns.

About The Author

I'm Dan Higgins, one of the faces behind The Teaching Couple. With 15 years in the education sector and a decade as a teacher, I've witnessed the highs and lows of school life. Over the years, my passion for supporting fellow teachers and making school more bearable has grown. The Teaching Couple is my platform to share strategies, tips, and insights from my journey. Together, we can shape a better school experience for all.






Join our email list to receive the latest updates.

Add your form here