Parallel structure is the repetition of a chosen grammatical form within a sentence. By making each compared item or idea in your sentence follow the same grammatical pattern, you create a parallel construction
Some examples are
1. Mary likes hiking, swimming, and riding a bicycle.
2. The production manager was asked to write his report quickly, accurately, and thoroughly.
3. The teacher said that he was a poor student because he waited until the last minute to study for the exam, completed his lab problems in a careless manner, and lacked motivation.
Some homework problems are
1. John Taylor Gatto criticizes public schools because they are compulsory, government-funded, and normalizing. Is this Parallel Structure? Yes.
2. Mike Taylor Gatto criticizes public schools because they require students to attend, receive money from the government, and destroy students' humanity. Is this Parallel Structure? Yes.
3. My dog not only likes to play fetch, but also chase cars. Is this Parallel Structure? No.