ACT® · English: Sentence Structure and Formation
Subordination and Coordination
Coordination joins two equal, independent clauses with a word like and, but, or so; subordination uses a word like because or although to make one clause depend on the other. The choice has to match the actual logical relationship between the ideas.
Two independent clauses can be joined two ways. Coordination keeps them equal, using a coordinating conjunction such as and, but, or so, usually with a comma before it. Subordination demotes one clause to a supporting role using a subordinating word like because, although, or when, turning it into a dependent clause that cannot stand alone. The grammar is only half the job: the word you pick has to match the real relationship between the two ideas. 'The road flooded and we turned back' is legal but empty, because and claims no relationship at all when the real one is cause and effect. Swap in so, or restructure with because, and the sentence finally says what happened.
The test on this point almost never asks you to spot a grammar error in isolation. It asks you to read both clauses, decide whether they are equal, contrasting, or cause-and-result, and then pick the connector that matches. and signals addition, but and although signal contrast, because and so signal cause and effect. Since although already marks the contrast at the front of a sentence, adding but in the middle is redundant and wrong: one relationship gets one marker, never two.
This sits next to comma splices and run-ons in the same unit, because faulty coordination and subordination often produce exactly those errors: joining two independent clauses with just a comma, or no punctuation at all. Mastering the menu of connectors here is what lets you fix those errors by choosing the right joint, not just adding a mark.
Key terms
- coordination
- joining two independent, equally weighted clauses with a word like and, but, or so.
- subordination
- using a word like because or although to make one clause dependent on the other.
- independent clause
- a clause with a subject and verb that can stand alone as a complete sentence.
- dependent clause
- a clause that starts with a subordinating word and cannot stand alone as a sentence.
- coordinating conjunction
- a word such as and, but, or so that links two equal clauses or phrases.
Watch it explained
- How it worksHow does a subordinating word demote one clause to a supporting role while coordination keeps both equal?
- Worked exampleWalk me through picking among 'and', 'but', 'because' and 'although' for 'The sky darkened' plus 'we kept hiking'.
- Common mistakeWhy doesn't 'and' work as a neutral default connector when the two clauses actually contrast?
- Common mistakeWhy isn't it legal to stack 'although' and 'but' together, as in 'Although it rained, but we went anyway'?
Check yourself
End of topic.