When talking about writing, it’s useful to imagine sentences as being constructed or made up of building blocks. These blocks can be put together strongly or weakly, and that construction will influence how clear a sentence is.
Think about parallel construction in a sentence. All the words and phrases inside the sentence need to be structured so that they are parallel, and this is a strong way of building a sentence.
Parallelism is the use of repeating grammatical structures to emphasize similarities between ideas.
EXAMPLEI like to sing, to dance, and to swim.
Notice how in that list, each of the verbs is in its infinitive form, meaning each begins with the word “to.” What if the form of one of those verbs changed?
EXAMPLEI like singing, to dance, and to swim
Here, “singing” has been conjugated to the present tense, but “to dance” and “to swim” haven’t been. Though the meaning hasn’t necessarily changed fundamentally, the sentence is much harder to understand, and the construction is weak overall.
Thus, lack of parallelism is not just grammatically incorrect, it’s also confusing for the reader. Especially with lists of verbs, you need to be careful to match tense and number.
It’s important to identify and correct errors related to parallelism. The verbs “reads” and “plays” are parallel in this example. Notice that they both match tense, so this list of two makes perfect sense.
Here, you have parallel adjectives, not verbs. In this list of three qualities about the kitchen, each description matches the others. Again, this is a clear sentence.
2a. Identifying and Correcting Errors #1
Take a look at the two sentences below describing Phil’s family. Everyone hates to read, and hates playing cards. Each separately is correct. It would make sense as written if each was on its own instead of in this list.
However, the sentence isn’t correct because the two items aren’t parallel. “To read” is in the infinitive tense, but “playing cards” is in the present tense. You can see the corrected version in green below:
2b. Identifying and Correcting Errors #2
Here is another sentence with a list of three adjectives. The list starts off well—cold and damp are parallel. Their structures match.
But then the way the list is put together changes, and the third item is “it was uncomfortable.” This is where the sentence stops being parallel. But this is easily fixed, too. See the corrected version in green below:
Source: This work is adapted from Sophia author Martina Shabram.