Definition: Ideas are considered parallel when they are grammatically equal. Ideas in a series must be parallel. You might have a series of nouns, a series of verbs, a series of prepositional phrases, a series of predicates, a series of independent clauses, or a series of some other grammatical element. Each item in the series should be the same thing.
A series of nouns: kitchen, bathroom, entryway
Please mop the kitchen, bathroom, and entryway.
A series of verbs: reading, writing, daydreaming (all are present participles)
The students in the class were reading, writing, and daydreaming.
A series of prepositional phrases: under the sofa, in the cushions, behind the television
I have looked for the remote control under the sofa, in the cushions, and behind the television.
A series of predicates: went to the store, bought some milk, came home
After school, I went to the store, bought some milk, and came home.
A series of clauses: Laura likes mysteries. Malachi prefers suspense. Shona loves romances.
Laura likes mysteries, Malachi prefers suspense, and Shona loves romances.
Too often writers pay attention to the ideas instead of the construction of the sentence.
Incorrect: We watched two movies, a television show, and read a book. (noun phrase, noun phrase, predicate)
Correct: We watched two movies, watched a television show, and read a book.
Incorrect: I want to go skiing, biking, or to go to the mall. (gerund, gerund, infinitive)
Correct: I want to go skiing, to go biking, or to go to the mall. (Now they are all infinitive phrases.)
Correct: I want to go skiing, biking, or shopping at the mall. (Now they all are gerunds following go)
Hint: Try putting each item in the series on its own line and see if they match.
I want to go
to go to the mall ✗