Sentence Structure

Thank goodness for sentences and sentence structure!

Sentences are nice little packages of words that come together to express complete thoughts.

They make it easy to understand ideas and learn information.

Without sentences, we'd probably all be walking around like a bunch of babbling idiots. :)

On this page, you're going to learn about simple sentences, compound sentences, complex sentences, and compound-complex sentences.

I'm also going to show you how to diagram those things because sentence diagraming is super-duper helpful when it comes to SEEING a sentence's structure.

Quick Refresher

In order to be a complete sentence, a group of words needs to contain a subject and a verb, and it needs to express a complete thought.

If a group of words is missing any of that information, it's probably a sentence fragment. If you have a group of words containing two or more independent clauses that are not properly punctuated, it is probably a run-on sentence.

Okay, now it's time for us to explore the four sentence structures!

The Four Sentence Structures

1. Simple Sentences

A simple sentence contains only one independent clause. An independent clause is a group of words (with a subject and a verb) that expresses a complete thought.

Here is a sentence diagram of a simple sentence. Note that there is only one horizontal line. 

grammar revolution simple sentence diagram

I drink coffee.

I drink coffee is an independent clause. It contains a subject (I) and a verb (drink), and it expresses a complete thought. Learn more about the simple sentence here.

2. Compound Sentences

A compound sentence contains at least two independent clauses. These clauses are joined by a coordinating conjunction or a semicolon. A coordinating conjunction is a word that glues words, phrases, or clauses together.

Here is a sentence diagram of a compound sentence. Note that there are now two horizontal lines and one is directly below the other.

grammar revolution compound sentence

She cooked and he cleaned.

She cooked is an independent clause. He cleaned is also an independent clause. And is a coordinating conjunction joining the two independent clauses. She cooked and he cleaned is a compound sentence. Learn more about the compound sentence here.

Psst! When you join two independent clauses with only a comma, it's called a comma splice. Avoid comma splices.

3. Complex Sentences

A complex sentence contains a subordinate clause and an independent clause. A subordinate clause is a group of words that has a subject and a verb but does not express a complete thought.

Here is a sentence diagram of a complex sentence. Note that there are still two horizontal lines, but one of them is below the other and moved to the right.

grammar revolution complex sentence

I washed the dishes after I ate breakfast.

I washed the dishes is an independent clause. After I ate breakfast is a dependent adverb clause modifying the verb washedI washed the dishes after I ate breakfast is a complex sentence.

Sometimes, it can be hard for people to tell the difference between compound sentences and complex sentences. You can learn more telling the difference here.

Learn more about the complex sentence here.

4. Compound-Complex Sentences

A compound-complex sentence contains at least two independent clauses and at least one subordinate clause.

Here is a diagram of a compound-complex sentence. Note that it's a hybrid of a compound sentence and a complex sentence! Two of the horizontal lines are directly above and below each other and the third is hanging out there in the middle.

grammar revolution sentence diagram

I would have purchased the cheese that you like, but it was too expensive.

I would have purchased the cheese and it was too expensive are both independent clauses. They are being joined by the conjunction but. 

That you like is a dependent adjective clause modifying the noun cheese. The whole sentence is a compound-complex sentence. Learn more about the compound-complex sentence here.

Sentence Diagramming Rules!

The great thing about diagramming sentences is that it shows how the parts of a sentence are related. Being able to see a sentence drawn out will help you understand sentence structure. Give it a shot!

Learn how diagramming can help you avoid sentence ambiguity.

If you want to teach or learn grammar the easy way, then follow a step-by-step program that clearly lays everything out for you and allows you to move at your own pace. The Get Smart program is presented in a logical sequence, so it's not an overwhelming mishmash of information. Before you know it, you'll be a grammar and sentence diagramming pro!

The whole program is online, so you have instant access to these lessons and videos. It's easy and fun. You can get it at
Grammar Revolution Get Smart Program
Keep learning and have fun!

Elizabeth O'Brien is the creator of the Grammar Revolution step-by-step grammar and sentence diagramming programs. Her programs are guaranteed not only to teach you grammar, but also to give you more confidence in your communication skills.

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Other Helpful Resources

Understand sentence structure? Learn about the types of sentences

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