Grammar Tips: That-Clauses

English is full of terminology that makes it seem more complicated than it really is. A that-clause, also known as a declarative content clause, is a good example. In this post, we’ll look at it in simple terms and then in more depth.

In Simple Terms

What Is a That-Clause?

The word “that” doesn’t work on its own; it only makes sense as part of a clause. A clause is a group of words with a subject (who or what the sentence is about) and a verb (what the subject is doing).

While some clauses make sense on their own (called independent clauses), others, including that-clauses, don’t. These are called subordinate clauses.

Although it doesn’t work on its own, a that-clause is used to connect two related ideas:

In More Depth

Having grasped the basic concept of that-clauses, let’s have a look at the different ways we can use them.

With a Verb

That-clauses are commonly used with verbs for reporting or describing the mental process:

He said that it would be safe.

I think that it would be a mistake.

With a Noun

Similarly, that-clauses may be combined with nouns for opinions and feelings and for reporting nouns:

I do this in the hope that you are right.

Your statement that this would be safe was misguided.

With an Adjective

Adjectives for opinions and feelings can also be expanded with a that-clause:

As the Object of the Sentence

This is where you will most often find a that-clause in English.

The subject of the sentence is “scientists.” “That pigs can fly” is the object.

As the Subject of the Sentence

Using a that-clause as the subject of a sentence is grammatically correct, but it’s less common because it can sound old-fashioned and formal:

Here, the subject of the sentence is “that you should doubt those scientists.”

Because it sounds old-fashioned and overly formal to put a that-clause in the usual place for the subject – at the start of a sentence – it’s better to rewrite the sentence with a different subject or rearrange it so the that-clause subject is later: