Same Writing › Sentences and editing › Simple, compound and complex sentences
What are FANBOYS and AAAWWUBBIS?
A simple sentence has one idea. A compound sentence joins two complete ideas with a comma and a FANBOYS word: for, and, nor, but, or, yet, so. A complex sentence joins an idea that can't stand alone using an AAAWWUBBIS word: after, although, as, when, while, until, because, before, if, since.
- Simple: one subject and verb, one idea.
- Compound: two sentences glued with a comma and a FANBOYS word.
- Complex: an AAAWWUBBIS part that needs the main sentence.
Why schools teach it
Variety makes writing stronger
Third graders produce simple, compound and complex sentences (L.3.1i). Seventh graders choose among them to show how ideas relate (L.7.1b). Rubrics often check “sentence variety.”
The silly acronyms make the joining words easy to remember. Using them also fixes run-ons and choppy sentences.
At the kitchen table
What to say, and what to skip
Say this
Can these two short sentences be joined?
CombineWhich FANBOYS word shows how they connect?
and, but, so...Comma before the FANBOYS word.
CompoundIf the sentence starts with an AAAWWUBBIS word, add a comma after that part.
Complex
Skip this
- Joining two sentences with only a comma.That's a comma splice. Add a FANBOYS word.
- Making every sentence long.Mix short and long. Variety is the goal.
- Calling any long sentence complex.Complex means it has an AAAWWUBBIS part, not just length.
See it in action
Combining “It rained. We stayed inside.”
Simple
It rained. We stayed inside.Compound
It rained, so we stayed inside.Complex
Because it rained, we stayed inside.
Some teachers call AAAWWUBBIS words subordinating conjunctions and FANBOYS coordinating conjunctions.
Free practice sheet
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Parents also ask
What does AAAWWUBBIS stand for?
After, Although, As, When, While, Until, Because, Before, If, Since. Some lists add a few more words.
When does a complex sentence need a comma?
When the AAAWWUBBIS part comes first: “When the bell rang, we left.” Not when it comes second.
What's a compound-complex sentence?
One with two complete ideas and an AAAWWUBBIS part. It's taught in grade 7.
What's a run-on?
Two sentences jammed together with no punctuation or joining word.