In my opinion, many schools sloppily use the “word of the day” or "word walls" as techniques for developing a broader vocabulary. I used the word sloppily because most classes consider this task with varying degrees of seriousness. Some classes spend time defining the words and making students give examples where they use the word in a sentence, while other classes ignore the words and breeze over them, occasionally using a quiz to superficially target a broadened vocabulary knowledge. For the most part this attempt to strengthen vocabulary seems too disjoint to take on an adequate sense of saliency. A work like The Crucible provides many vocabulary opportunities. Many students may find The Crucible a tough read, which is due largely to the fact that it contains many words that are uncommon in the everyday use spoken English.
I believe that actual units should provide means by which students learn new vocabulary because any class, in any content area, consistently provides enough examples of new vocabulary. Learning vocabulary helps students more easily comprehend the texts that they are reading as well as the language and context of a particular piece of writing. This means that a narrative based around trials, hearings, and religious values, such as The Crucible, is going to use language of religious and legal terms. A biology textbook may use entirely different language, but it will have vocabulary words that are necessary for and relevant to a student's learning. I think that the “word of the day” or “word walls” should not be used unless the pertain to specific classroom knowledge. Focusing on the vocabulary of a particular class is an important part of student understanding, so why not make sure you and your students are attending the vocabulary from within your own texts?
Below are some websites which provide some helpful vocabulary for The Crucible:
http://www.fcps.edu/westspringfieldhs/academic/english/1project/crucible/vocab.pdf
http://noir.usd458.org/blvsEnglish3/stories/storyReader$35
https://secure.layingthefoundation.org/english/vocab/novels/The%20Crucible.pdf
http://www.proprofs.com/flashcards/story.php?title=Crucible-Vocab-Quiz