What is a Sentence?

Learning Objectives

  • Critique passages, revising for run-on sentences and fragments

Basic Sentences

What is a sentence? That’s actually a harder question to answer than you might think. Sometimes students think of a sentence as a complete thought. But what is a complete thought?

A complete sentence always contains a verb, expresses a complete thought, and makes sense standing alone:

  • Kamal reads quickly.

This is a complete sentence as it contains a verb (reads), expresses a complete idea, and does not need any further information for the reader to understand the sentence. “Kamal reads” is also a complete sentence – although it doesn’t give us as much information as we might like.

  • When Kamal reads.

This is an incomplete sentence. It contains a verb, but the opening word when tells us that something happens when Kamal reads, but it doesn’t tell us what that something is; we need more information to complete the idea.

  • When Kamal reads, he reads quickly.

This is now a complete sentence, as the whole idea of the sentence has been expressed.

Here’s another example of a super simple sentence:

  • Asha swims.

We know the subject (Asha), and we know what Asha does (swims). Obviously, without both pieces, it’s not a sentence. Asha can’t be a sentence on its own: What is Asha doing? Swims can’t be a sentence on its own: Who swims?

More Complex Sentences

Let’s look at some slightly more confusing examples:

  • Asha swims. As she tries to train for a triathlon.

We know the first part – “Asha swims” – is a sentence. What about the second – “As she trains for a triathlon”? What happens as she trains for a triathlon? We don’t know. “She trains for a triathlon” is a sentence. But “As she trains for a triathlon” is incomplete.

We often make mistakes just like this one because we split up a sentence into incomplete parts. Instead of – “Asha swims. As she trains for a triathlon.” – we could simply write – “Asha swims, as she trains for a triathlon.” Or – “As she trains for a triathlon, Asha swims.”

Of course, lots of real sentences are long and complicated, and that can make figuring out whether they are complete sentences even more tricky. Let’s look at another example:

  • My sister and I, having studied the application and applying for the job.

Is this a sentence? The sentence is about me and my sister. What did we do? Hmm … not so clear. Rearranging the sentence can make the issue even more obvious:

  • Having studied the application and applying for the job, my sister and I.

Can you see the issue now? You can simplify the sentence further to make the issue even more clear:

  • Having studied, my sister and I.

Really, the heart or core of the sentence is this: “My sister and I.” Clearly not a sentence. “My sister and I were awaiting news about the job, having studied the application and applying for the job.” Now the core of the sentence is complete: “My sister and I were awaiting news.” The subject is “My sister and I.” What were we doing?: (we) were awaiting news.

You can see one of the tricks we can employ to see if the sentence is complete is to try to find the core of the sentence and eliminate all the extra bits. Let’s practice.

Try It

All Sentences Need a Core

A word board that says "Difficult roads lead to beautiful destinations."

Figure 1. Which part of the above quote would you identify as the “core” of the sentence?

Here’s another way to think about the core of a sentence. Let’s look at some examples that are missing the core.

  • After sitting for nearly an hour by the pool,

We need to add the core.

  • After sitting for nearly an hour by the pool, Asha swims.

Again, we can remove the extra bit and the core is the same: Asha swims.

How about this example?

  • Surviving the virus

We need to add the core.

  • Asha swims surviving the virus.

Okay, that’s confusing, but “Asha swims” still works as the core. It just doesn’t make sense. Let’s switch out swims for another verb – is. “Asha is surviving the virus.” Now, “Asha is surviving” is the core. What is she surviving? That’s extra, not part of the core of the sentence.

Writing Workshop: What is a Sentence?

Open your Working Document to the section “What is a Sentence?”

Let’s take some sentence fragments and turn them into full sentences by adding more to the fragments. You may need to add punctuation as well, which we will be discussing in more detail on the next page.

1. Because I am generally a happy person,

2. Although I love school

3. Failing math class

4. Evaluating the evidence

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