College students handle complicated and interrelated ideas, requiring a wide range of sentence structures to express clearly. Writers need to consciously match these structures to the ideas they represent, as well as to vary patterns to keep the reader’s attention. For instance, the compound-complex sentence, as the most complicated sentence, is best used sparingly alongside simple, compound, and complex sentences to guide readers through logical relationships.

Here is a paragraph of simple sentences all relating to the same subject:

The Burgess Shale contains important fossils. The Burgess Shale is in the Canadian Rockies. The fossils represent the diverse life forms of the Cambrian Explosion. These complex life forms evolved from the single-celled organisms of the Ediacaran Period. Many fossils preserve only the hard parts of organisms. Sometimes, the organisms are not preserved at all. The fossils of the Burgess Shale were formed by an under-sea avalanche of fine mud. They show the soft parts as well. *

(Note: Subjects are bolded and verbs italicized throughout this page.)

All those simple sentences in a row feel choppy and disconnected. Let’s consider what combinations will help the reader best grasp these ideas.

• The second sentence repeats material from the first sentence; shortening that whole sentence to a prepositional phrase and moving it to modify the subject of the first sentence eliminates wordiness:

The Burgess Shale (in the Canadian Rockies) contains important fossils.

• The third sentence gives information about the “important fossils” of the first; the word “fossils” in the third sentence can be replaced with a relative pronoun. The resulting relative clause can then be attached to the first to create a complex sentence:

The Burgess Shale in the Canadian Rockies contains important fossils (which) represent the diverse life forms of the Cambrian Explosion.

• We could wrestle with the fourth sentence to join it to the complex sentence we just created, but fashioning the logical connections would be awkward, so it may be best to leave it a simple sentence:

These complex life forms evolved from the single-celled organisms of the Ediacaran Period.

• The last four sentences all talk about the same basic idea, but what connections show those links? The “Sometimes” sentence offers an alternative to the “Many fossils” sentence and both seem equally important, so let’s join them with an “or.” The next-to-the-last sentence is a cause of the last sentence, but again, both ideas are equally important, so join them with “so.”

Many fossils preserve only the hard parts of organisms, (or) sometimes, the organisms are not preserved at all. The fossils of the Burgess Shale were formed by an under-sea avalanche of fine mud, (so) they show the soft parts as well.

• We could leave it at that, but there are other options! Looking back at the two compound sentences we just created, the first seems to lay the groundwork for the second; adding a subordinate conjunction and attaching the resulting subordinate clause to the second compound sentence creates a compound-complex sentence.

(While) many fossils preserve only the hard parts of organisms, or sometimes the organisms are not preserved at all, the fossils of the Burgess Shale were formed by an under-sea avalanche of fine mud, so they show the soft parts as well.

• These choices are not the only right choices; they are simply the choices that seemed to most clearly express for this writer the relationships between these ideas:

The Burgess Shale in the Canadian Rockies contains important fossils which represent the diverse life forms of the Cambrian Explosion. These complex life forms evolved from the single-celled organisms of the Ediacaran Period. While many fossils preserve only the hard parts of organisms, or sometimes the organisms are not preserved at all, the fossils of the Burgess Shale were formed by an under-sea avalanche of fine mud, so they show the soft parts as well.

Here is another paragraph full of choppy sentences to play with if you would like to practice combining ideas:

The hyolith was a denizen of Cambrian seas. Charles Doolittle Walcott discovered hyoliths. Their fossils are in the Burgess Shale. The hyolith’s body was housed in a slender conical shell. The mouth of the cone was closed with a protective shell-shaped door or lid. This lid is called an operculum. Two arms projected through the operculum. Walcott called the arms “helens” after his daughter. The hyolith may have used them to stabilize itself in the ocean currents. Some scientists speculate the hyolith may have also used the arms to row itself along the sea floor.

 

*All examples based on information from “The Burgess Shale.” Smithsonian National Museum of Natural History. Smithsonian Institution. 2015. Web. 7 May 2014.