Beck, McKeown, and Kucan (2002) present a useful
framework for classifying vocabulary and making
instructional determinations regarding which words to
teach and how to effectively teach them. According to
this model, vocabulary within a given reading selection
can be grouped into three tiers with Tier 2 words being
the most productive for explicit, in-depth instruction.
Tier 1 words are the commonly-occurring, basic words
of English; these are lexical items that native speakers
of a language easily recognize, such as map, uncle, tall,
sing, and dog. Tier 2 words are academic vocabulary
and other lexical items which appear frequently across
a variety of domains. Words such as coincidence,
industrious, and investigate fall into this category. Tier
2 words are typically essential for understanding the
meaning of a text. Finally, Tier 3 words are lowfrequency
words such as amoeba, isotope, or lathe,
which are often discipline-specific. A more detailed
overview of the three tiers of words, with specific
commentary regarding the language of second language
learners (Calderon, 2007) is provided below