Complex Sentences: Fifth Grade English Student Guide

Complex sentences weave dependent conditions, causes, and times into independent clauses, allowing writers to express layered, mature thoughts with clarity and style.

What is a Complex Sentence?

A complex sentence contains exactly one independent clause and at least one dependent (subordinate) clause. This structure establishes a clear hierarchy of ideas, showing which concept is the primary point and which concept provides supporting context, condition, or reason.

+--------------------------------------------------------------+
|                 COMPLEX SENTENCE STRUCTURE                   |
|                                                              |
|   [ INDEPENDENT CLAUSE ]       +      [ DEPENDENT CLAUSE ]   |
|   (Main, dominant thought)           (Subordinate condition) |
|                                                              |
|   The rescue ship arrived       after the storm subsided.    |
|   (Independent Clause)               (Dependent Clause)      |
+--------------------------------------------------------------+

The Subordinating Conjunction Engine

The engine that transforms an ordinary clause into a dependent clause is the subordinating conjunction. Words such as although, because, since, unless, while, when, whenever, before, and after signal that the attached clause cannot stand alone.

The Comma Rule for Complex Sentences

Punctuation in a complex sentence depends entirely on the physical order of the clauses. The position of the dependent clause determines whether a comma is required.

+--------------------------------------------------------------+
|               THE COMPLEX SENTENCE COMMA RULE                |
+--------------------------------------------------------------+
| ORDER 1: Dependent Clause FIRST                              |
| [ Dependent Clause ], [ Independent Clause ].                |
| "Because the road was flooded, we took the detour."          |
| (COMMA REQUIRED after introductory dependent clause)         |
+--------------------------------------------------------------+
| ORDER 2: Independent Clause FIRST                            |
| [ Independent Clause ] [ Dependent Clause ].                 |
| "We took the detour because the road was flooded."           |
| (NO COMMA generally needed)                                  |
+--------------------------------------------------------------+

Why Does the Introductory Clause Need a Comma?

When a reader begins reading a sentence that starts with a dependent clause, the comma serves as a vital road sign indicating where the introductory background ends and the main action begins. Without that comma, readers may stumble and re-read the sentence.

Combining Simple Sentences into Complex Sentences

Relying exclusively on short, simple sentences makes writing sound choppy and repetitive. Transforming pairs of simple sentences into complex sentences elevates your writing style.

+--------------------------------------------------------------+
|                 SENTENCE ELEVATION EXAMPLE                   |
+--------------------------------------------------------------+
| CHOPPY: The sun sank behind the mountains. The temperature   |
|         dropped twenty degrees immediately.                  |
+--------------------------------------------------------------+
| ELEVATED (Complex): As soon as the sun sank behind the       |
| mountains, the temperature dropped twenty degrees immediately|
+--------------------------------------------------------------+

Exercises and Solutions

Exercise 1: Identifying Clauses in Complex Sentences. For each complex sentence, identify the independent clause, the dependent clause, and the subordinating conjunction: Sentence A: "Although the climb was grueling, the mountaineers reached the peak before twilight." Sentence B: "The wildlife biologist remained motionless while the grizzly bear crossed the meadow."

Solution 1: In Sentence A, the independent clause is "the mountaineers reached the peak before twilight." The dependent clause is "Although the climb was grueling," and the subordinating conjunction is "Although." In Sentence B, the independent clause is "The wildlife biologist remained motionless." The dependent clause is "while the grizzly bear crossed the meadow," and the subordinating conjunction is "while."

Exercise 2: Punctuation Correction. Look at this sentence: "Since the telescope was properly calibrated the astronomer discovered two new asteroids." Explain what punctuation mark is missing and rewrite the sentence correctly.

Solution 2: The sentence begins with an introductory dependent clause ("Since the telescope was properly calibrated"), which must be followed by a comma before the independent clause begins. The correctly punctuated sentence reads: "Since the telescope was properly calibrated, the astronomer discovered two new asteroids."