Which vocabulary words should you focus on? There are three recognized "tiers" or levels of vocabulary. The Common Core urges literacy instructors to focus on teaching "Tier 2" or "Academic" vocabulary.
Tier 1 words like "house" and "happy" are not the focus because it is assumed that students hear and speak these words on a daily basis. Students may struggle with spelling these words, but these words do not create reading comprehension barriers.
Tier 3 words like "hypotenuse" or "enzyme" are not the focus of literacy instruction because they are discipline specific, meaning that students will only have infrequent encounters with these words in content-specific classes.
Tier 2 words are the desired focus of literacy instruction because they are used across disciplines and have multiple meanings depending on context (consider all of the meanings and uses of the word "average" - an average day; average height; please average these numbers). It is their common use acrossacademic disciplines or contexts that makes an instructional focus on them such an ideal focus. The assumption is that students will encounter these words with more frequency, thus have a better chance of mastering this essential vocabulary used across academic texts.
Use this criteria for selecting Academic or Tier 2 vocabulary words from text:
Is this word used frequently across contexts or disciplines?
Is this word more common in writing than everyday speech?
Is this word important for comprehension of this text?
Is this word part of a semantic word family? Does it have different meaning
Pearson's Reading Maturity Metric is a useful tool for determining the complexity of a text as well as for identifying "mature" or "academic vocabulary words from text. All you need to do is copy and paste a text into this tool and it will list and highlight the "top maturity words" for you to get you started.
Another free online tool to assist you with vocabulary selection only is VocabGrabber.