4.2 Subordination and Coordination

Two Ways to Join Ideas

The Sentence Structure category names this skill directly:

Subordination and coordination: The student will recognize and correct problems in coordination and subordination in sentences.

English offers two systems for joining clauses. Coordination treats them as equals. Subordination makes one dependent on the other. Choosing wrongly between them, or executing either incorrectly, produces the errors this skill targets.

Coordination

The Seven Coordinating Conjunctions

Remembered as FANBOYS: for, and, nor, but, or, yet, so. Each asserts a specific relationship:

The Comma Rule

When a coordinating conjunction joins two independent clauses, a comma precedes it:

The lab ordered replacement reagents, but the shipment was delayed three weeks. ✓

When the conjunction joins something less than two independent clauses — a compound predicate, for instance — no comma:

The lab ordered replacement reagents and scheduled a second trial. ✓

Here scheduled a second trial has no subject of its own; it shares the lab. Inserting a comma is a superfluous comma error.

The test: cover the conjunction and ask whether what follows could stand alone as a sentence. If yes, comma. If no, none.

Coordination Errors

Comma splice — two independent clauses joined by a comma alone, with no conjunction:

✗ The reagents arrived late, the trial was postponed.

Five repairs: add a coordinating conjunction (late, so the trial), use a semicolon (late; the trial), use a period, subordinate one clause (Because the reagents arrived late, the trial), or use a colon if the second explains the first.

Faulty coordination — using and where a real relationship exists:

✗ The reagents arrived late, and the trial was postponed.

Grammatically flawless, rhetorically weak. And asserts mere addition, concealing the causal link. Better: so, or subordination.

Wrong connective — the conjunction names the wrong relationship:

✗ The reagents arrived on schedule, but the trial proceeded as planned.

But claims contrast between two facts that agree. Should be and or so.

Subordination

Subordinating Conjunctions

A subordinating conjunction makes a clause dependent — unable to stand alone:

Adding one to the reagents arrived late yields because the reagents arrived late — no longer a sentence. That is the definition of subordination, and it is also how fragments get made: a dependent clause punctuated as a sentence.

Comma Placement

Dependent clause first → comma:

Because the reagents arrived late, the trial was postponed. ✓

Dependent clause second → usually no comma:

The trial was postponed because the reagents arrived late. ✓

The main exception is a trailing clause of genuine contrast, where a comma is acceptable:

The trial proceeded on schedule, although the reagents arrived late. ✓

The Double-Connective Error

English permits one connective per joining, not two. Using both a subordinator and a coordinator creates a fragment:

✗ Although the reagents arrived late, but the trial proceeded on schedule.

Although already established the contrast; but repeats it and leaves no independent clause. Remove either word:

✓ Although the reagents arrived late, the trial proceeded on schedule. ✓ The reagents arrived late, but the trial proceeded on schedule.

This error is common in speech and appears regularly on the test.

Choosing Between Them

When both are grammatical, the decision is rhetorical:

• Coordinate when the ideas deserve equal weight, or the stem asks for balance.
• Subordinate when one idea genuinely serves the other, and when you want the relationship made explicit.

Subordination is generally the more informative choice, because because, although, and when each name a relationship, whereas and names none. But a passage built entirely from subordinated clauses becomes dense and hard to follow, so neither system is right by default.

Conjunctive Adverbs Are Not Conjunctions

A persistent trap. Words like however, therefore, moreover, nevertheless, consequently, furthermore, and thus are conjunctive adverbs. They express relationships but cannot grammatically join clauses.

✗ The reagents arrived late, however the trial proceeded on schedule.

This is a comma splice, not a valid coordination. Correct forms:

✓ The reagents arrived late; however, the trial proceeded on schedule. ✓ The reagents arrived late. However, the trial proceeded on schedule.

The pattern to memorize: semicolon before a conjunctive adverb joining clauses, comma after it. Distinguishing FANBOYS (which join with a comma) from conjunctive adverbs (which require a semicolon or period) resolves a large share of punctuation-adjacent sentence-structure items.