Sentences: Simple, Compound, and Complex

The lesson here on three types of sentence is presented for non-native speakers of English, or speakers with limited English proficiency. Most native English speakers probably got lessons like these in their first eight or nine years of school.

But depending on the instruction and practice back then, memories of those English lessons may have faded. And with those faded memories may also be lost understanding of the value to communication of using these various sentence structures.

The lesson begins:

Experienced writers use a variety of sentences to make their writing interesting and lively. Too many simple sentences, for example, will sound choppy and immature while too many long sentences will be difficult to read and hard to understand.

That's a useful, true statement. And the rest of the lesson provides a clear explanation of how each sentence type is structured.

But I'd like to emphasize a few other points to help ensure clear, concise writing -- and thus, quality communication -- for all writers, native English speakers or not.

The simple, declarative sentence is the easiest to understand: Someone (or something) does (or is) something. Sentences that differ from that simple structure may cause readability problems for some people.

Readers can only take in so much new information at once. Short, simple sentences are less likely than the longer compound and complex sentences to include ambiguities that reduce readability or hinder translation.

Make the average sentence length in your document 20 words. That means, of course, that some sentences can be shorter than 20 words, and some can be longer. Readers can understand some longer sentences (up to 30 words) if they are well written and use familiar terms.

As the lesson says, too many short simple sentences can become repetition and boring. So some carefully written compound and complex sentences are acceptable.

But those compound and complex sentences should be 30 words or shorter, and they should stick to only one idea. If you're trying to cover two ideas in a compound or complex sentence, it's better for the reader if you break the sentence into two.

For more information on clear, concise writing, check out Garbl's Plain English Writing Guide.