Simple, Compound, Complex Sentences

Writing good sentences.

“Wisdom will help you follow the example of good people and stay on the right path.” Solomon

Successful writers use a variety of sentences to make their essays interesting and effective.  If a writer uses too many simple sentences, the passage is often difficult to read.  On the other hand, if a writer uses too many complex sentences, the passage becomes difficult to understand.  A balance of simple, compound and complex sentences not only makes an essay more readable, but also adds depth and meaning.

Simple Sentence

Simple sentences need three things to be correct. They need a subject, a verb, and they need to be a complete thought.
The subject is a person, place, or thing; it is what the sentence is about. The verb shows the action the subject is doing, such as “He is eating a sandwich.” or the state the subject is in, such as “He is standing.”  A simple sentence also needs to express a complete thought or a complete idea. In other words, if the sentence reads, “I bought.” We would ask the question, “What did you buy?” “I bought” has a subject and a verb, but it is not a complete thought.
Some verbs are intransitive verbs, like “He laughed”. This sentence has only a subject and a verb, but it is also a complete thought, because intransitive verbs don’t need a direct object.

Below are three examples of simple sentences, also called independent clauses.

  1. Thomas Edison invented the light bulb.
  2. The company is hiring new employees.
  3. Students often study at the library.

A simple sentence may also have a compound subject or a compound verb, as in the sentences below.

  • Compound Subject: Thomas Edison and Henry Ford were American inventors.
  • Compound Verb: The company is hiring and training new employees.
  • Compound Subject and Verb: After school, boys and girls study and learn at the new science center.

NOTE: If a sentence does not have a subject or a verb, or does not express a complete thought, then we say the sentence is a fragment.

Below are examples of sentence fragments

  1. No subject: Took the test in the Fall. (Who took the test in the Fall?)
  2. No verb: The students the test in the Fall. (What did the students do?)
  3. Incomplete thoughtIn the Fall. (Who did what in the Fall?)
  4. Correct sentence: The students took the test in the Fall.

Compound Sentences

Two independent clauses (two simple sentences) joined by a coordinator is known as a compound sentence.  The seven coordinators are for, and, nor, but, or, yet, so.  If you take the first letters of each coordinator, they spell FANBOYS. This makes it easier to remember.

Independent Clause + coordinator + Independent Clause = Compound Sentence 

To better understand compound sentences, look at the examples below.

  1. The company built a new factory, so they are hiring new employees.
  2. Some students study better in the morning, and other students study better in the evening.
  3. Students often go to a gym to get exercise, but  it is better to get exercise in the open air.

Complex Sentences

A complex sentence is an independent clause joined by one or more dependent clauses.  When we join these two clauses together, we use subordinators, such as after, before, because, since, or when.

We can also use a relative pronoun such as who, that, or which.

Independent Clause + subordinator + Dependent Clause = Complex Sentence

Look at the examples below.

  1. After Thomas Edison invented the light bulb, people did not need to use kerosene lights.
  2. Because students study hard, they need to get enough exercise everyday.
  3. Students often leave the classroom when they are finished taking a test.

Note: When a dependent clause is followed by an independent clause, the comma is used.When an independent clause is followed by a dependent clause, the comma is not used.

Sentences with an adjective clause are also called a complex sentence, because they contain an independent clause and a dependent clause.

  1. The school usually has graduation in the park where the lake is.
  2. Thomas Edison, who made over one thousand inventions, died at the age of 84 in 1931.
  3. The company that makes computer components is hiring new employees.
  4. People who are kind to others are happier.

NOTE: Sentence Fragments are commonly seen when using dependent clauses. A dependent clause has a subject and verb, but it does not express a complete thought. Dependent Clauses need  Independent Clauses to be considered a complete sentence.

Look at the examples below.

  1. After the project was finished.
    • What happened after the project was finished?
    • Correct: After the project was finished, the researches published their findings.
  2. When they gave the blankets and food to the hungry.
    • What happen when they gave the blankets and food to the hungry?
    • Correct: When they gave the blankets and food to the hungry, other people joined them in the fight against poverty.
  3. Mother Theresa, who helped the poor of Calcutta.
    • The dependent clause identifies Mother Theresa, but it does not tell us what she did.
    • Correct: Mother Theresa, who helped the poor of Calcutta, influenced thousands to have compassion on the less fortunate.


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