Headwords labeled with a number from 1 to 5 belong to the Wordsmyth Vocabulary Index (WVI). The WVI is a list of what we consider to be the 10,000 most important academic vocabulary words. They are grouped into five levels of difficulty, with level 1 words being the least difficult and level 5 the most difficult. The five levels correspond approximately to five grade-level bands:
- level 1 grades K-2
- level 2 grades 3-6
- level 3 grades 7-9
- level 4 grades 10-12
- level 5 grades 12+
The WVI words can be viewed alphabetically at the Search Filters page (under the Search Tools menu). The WVI words were selected by analyzing the Educator’s Word Frequency Guide, which provides grade-specific data on word frequency for words taken from a 17-million-word corpus of texts used in K-12+ education. Words used across the curriculum were given precedence over domain-specific vocabulary. This general academic vocabulary corresponds with the “Tier 2 words” emphasized as important in the Common Core State Standards for literacy. Additional established vocabulary resources, such as Coxhead’s Academic Word List (AWL), Elfriede Hiebert’s Word Zones, and the Corpus of Contemporary American English, were also consulted in order to both narrow down and validate our initial reservoir of vocabulary words.