Grammar:

Parallel Construction

Parallel ideas must be presented in parallel grammatical form, which means that each part of a sentence uses the same grammatical structure.

"Between" and "And"

Incorrect:  We debated the difference between the weather in Minnesota in the winter and how hot it is in the summer.
 
Correct:  We debated the difference between the weather in Minnesota in the winter and the weather in Minnesota in the summer.

"Both" and "And"

Incorrect: The films were enjoyable both to watch and for discussing.
 
Correct: The films were enjoyable both to watch and to discuss.

"Neither" and "Nor"; "Either" and "Or"

Incorrect: Neither the responses to the questionnaire nor what we asked on the survey were answered.
 
Correct: Neither the responses to the questionnaire nor the responses to the survey were answered.

"Not Only" and "But Also"

Incorrect: It was surprising not only that the house sold, but also it sold well over the asking price.
 
Correct: It was surprising not only that the house sold but also that it sold well over the asking price.

Sentences with lists require particular attention to parallel construction.

Example 1:

Incorrect: This paper will address No Child Left Behind, how to teach effectively, and instructing with multimedia aids.
 
Correct: This paper will address No Child Left Behind benchmarks, effective teaching strategies, and multimedia instructional aids.

Now, the list has parallel elements (benchmarks, strategies, and aids are all plural nouns).

Example 2:

Incorrect: The students were unprepared, poorly behaved, and disrupted the class.
 
Correct: The students were underprepared, poorly behaved, and disruptive.

Now, the list has parallel elements ("underprepared," "behaved," and "disruptive" are all adjectives).

For more help with parallel structure in a list, see the APA Style blog post on lists.