When to Use Which or That

When to use which or that has always been known as one of the most grammatically confusing grammar lessons ever taught. The fact that the two words are interchangeable does not make a lesson on either word that much easier. You could sit through four years of English classes and still not understand when to use “which” or “that.” Hopefully the illustrations below will help you understand a little better.

Restrictive and Non-Restrictive Elements

The elements up for illustration are not Earth, wind or fire. Let’s talk sentence elements. Two come to mind – they are, restrictive and non-restrictive elements.

• A restrictive element is a word, phrase or a clause that manages to limit the meaning of the sentence element that it modifies. When a restrictive element is not included then the entire meaning of the sentence will change.

• The non-restrictive element is a word, phrase or a clause that provides excess information about the beginning of a sentence without restricting the meaning of that part of the sentence.

Keep these two definitions in the back of your mind because they will be crucial understanding when to use “which” or “that.”

Using Which vs. That

That Is Restrictive

The word “that” is considered to be a restrictive element of any sentence that it may be used in.

If you take a quick look at the definitions above, you will see that a restrictive element limits the meaning of the sentence element that it modifies. For example if you used the following sentence, “Baby foods that contain soybeans are best.” The restrictive element of the sentence are the words “that contain” because these words restrict the type of baby food that is being discussed. 

In effect without the words “that contain” the whole sentence meaning would be altered. You can see that without the words “that contain” there would be no restrictive element of the baby food. Instead the sentence would imply that all baby food is best.

Let’s examine the notion of the non-restrictive element. Reverting to the definition above, a non-restrictive element is a word, phrase or a clause within a sentence that only serves as additional information – an info item so to speak.  Should a non-restrictive item be left out of the sentence then it will not change the meaning of the sentence whatsoever. 

Which Is Not Restrictive

You can usually recognize a non-restrictive element because it is surrounded by commas or parentheses. Here is an example (working from a similar version of the sample sentence above) of how a non-restrictive element using the word “which” should be used. “Soybean baby foods, which are Sally’s favorite, work well for her diet.”

Can you see the difference between how the word “that” (a restrictive element) and the word “which” (a non-restrictive element) work in a sentence? Take a look again. If you look at the illustration for a non-restrictive element (or the word “which”) you can see how if you removed the phrase “which are Sally’s favorite” the meaning of the sentence does not change. The only thing that the phrase “which are Sally’s favorite” does is provide additional information.

It is important, when reviewing how to use “which” or “that” in a sentence that you take your time and let the lesson sink in. If you read it too fast, you may miss it and get confused. When you are learning about restrictive and non-restrictive elements it is crucial that you pay close attention. The slightest distraction could lead you to use the words “which” and “that” in the wrong context. When it comes to these words it helps to fully understand the role that they play in sentence structure.

For more information on how to effectively use the words “which” and “that” you might want to consult your local English or Grammar department or log on to the Internet and search through the grammar lessons that many teachers have listed. These lessons can be invaluable in discerning the proper usage of the words.