1. What is a Compound Sentence?
A compound sentence allows us to share a lot of information by combining two or more related thoughts into one sentence. It combines two independent clauses by using a conjunction like “and.” This creates sentences that are more useful than writing many sentences with separate thoughts.
Compound sentences are important because they allow us to shorten the things we say or write. They express our thoughts in a way that allows our audience to receive information easily and quickly. Often, everything we want to say can be summarized, and it is generally the best choice for communicating. So remember: more words don’t necessarily mean more information.
2. Examples of Compound Sentences
We use compound sentences all of the time. Here are some examples, the independent clause is green, the second is purple, and the conjunctions are orange:
- I drove to the park, and then I walked to the beach.
- Mike drove to the park, and I walked to the beach.
Let’s take a look at the following section to find out what is an independent clause and a conjunction.
3. Parts of Compound Sentences
A compound sentence has at least two independent clauses and always includes a conjunction.
a. Independent Clause
- The parrot ate popcorn.
- The wolf ran quickly.
- He ate candy apples.
- He went to the mall.
So, you can see that all of the clauses above are working sentences. All sentences have an independent clause, but all compound sentences have at least two independent clauses.
A conjunction is a word in a sentence that connects other words, phrases and clauses. The most common conjunction that you know is “and.” Other common conjunctions are for, but, or, yet, and so. A compound sentence needs at least one conjunction to connect two or more complete sentences.
Conjunctions are important because they let us combine information, but still keep ideas separate so that they are easy to understand. A compound sentence without a conjunction would be a run-on sentence, and would sound very confusing! Here are two sentences, with and without conjunctions:
The boy ran to the park then he ate a hotdog.
The boy ran to the park, and then he ate a hotdog.
So, you can see that we need a conjunction to for the sentence to be clear!
It is important to know that the word “then” is NOT a conjunction—it’s an adverb. So, when you are writing a compound sentence and want to use “then”, you still need a conjunction, for example, “so then,” “but then,” or “and then.”
4. Types of Compound Sentences
As mentioned, a compound sentence combines two independent clauses. Some common formats for compound sentences are:
- one subject performing two different actions
- two completely different subjects doing performing actions
a. When one subject does more than one thing:
The boy ran to the park.
The boy ate a hotdog there.
These sentences have the same subject, “boy,” but two verbs, “ran” and “ate.” Since both sentences are about what the boy does at the park, we can combine them:
The boy ran to the park, and he ate a hotdog there.
This compound sentence is the best way to share the information from the two original sentences. Even though the boy does two different things, we can explain them in one sentence because they are related to each other.
Remember not to confuse this with a compound predicate. We can also say:
The boy ran to the park and ate a hotdog there.
In this example, we don’t mention the boy twice, so we don’t have two separate sentences. Ate a hotdog is only a verb phrase, so we don’t need a comma.
Let’s try another example, again starting with two sentences.
Every morning, Shelly eats breakfast.
After breakfast, Shelly works in her garden.
Both of these sentences describe what the subject, Shelly, does every morning. Why not say this in one sentence?
Every morning, Shelly eats breakfast, and then she works in her garden.
In this example, we have two complete sentences joined by a coordinating conjunction, so we use a comma.
But, if we eliminate the subject, we can write a sentence with a compound predicate:
Every morning, Shelly eats breakfast and then works in her garden.
In this example, we have two complete verb phrases, so we don’t use a comma.
Either way, the compound sentence is much stronger than two separate sentences.
b. When multiple subjects do the same thing:
Yesterday the lion went to the candy store.
The zebra also went to the candy store yesterday.
Both subjects, “the lion” and “the zebra,” went to the candy store yesterday. So, let’s combine these things:
Yesterday, the lion went to the candy store, and the zebra went, too.
Also, you should know that in contrast, combining the subjects makes a compound subject, but NOT a compound sentence:
The lion went to the candy store, and the zebra went too. Compound sentence
The lion and the zebra went to the candy store. Compound subject
c. When multiple subjects do multiple things:
The girl ate cake at the party. Subject “girl,” verb “ate”
The cat drank soda at the party. Subject “cat,” verb “drank”
Even though these two sentences are about two different subjects doing two different things, they both share the phrase “at the party.” Since they have this information in common, we can combine them:
At the party, the girl ate cake but the cat drank soda.
5. How to Write a Compound Sentence and Avoid Mistakes
Compound sentences are a great tool in writing, and come naturally in speaking. As mentioned, they exist to help you unite multiple related ideas into one strong sentence. For example, here are three simple sentences:
- The cheetah ran fast.
- She ran all the way to the movies.
- There, she ate a hot pretzel.
We really don’t need three separate sentences to share this information, because it’s all about the same subject. So, let’s combine all three of the sentences above to make one compound sentence:
The cheetah ran fast; she ran all the way to the movies, and there she ate a hot pretzel.
The compound sentence still has the subject “cheetah,” but it now shares both of the things she did at the county fair, “ran” and “ate.”
Finally, it’s important to remember that compound sentences combine related information. Even if you follow the proper grammar pattern, it doesn’t mean you can combine any old thing with another. You don’t want to make the mistake of putting things together that have nothing to do with each other, like this:
Mary went to the market yesterday and she gardens every morning.
In this sentence, the first point is that Mary went to the market yesterday, and the second is that she gardens every morning. But, these things are not related to each other, even though they are both about Mary. It seems like they came from two different stories. So, while there is nothing wrong with the grammar, this is not a proper compound sentence because the ideas are unrelated.