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Word Dynamo
Pros: Preexisting lists cover a broad range of vocabulary in levels appropriate for all ages of readers.
Cons: Searchable lists don't appear to be moderated, so kids can access lists that were likely created just to shock.
Bottom Line: Word Dynamo is an easy-to-use vocabulary-building app that works with a wide range of skill levels.
Teachers can create word lists to share via email or social media with their students, or kids can create lists in reading groups or individual lists. Each kid will need to create an account on Dictionary.com (which can be done within the app), but as long as each logs off and logs in, multiple users can use the same device at different times.
Kids start off with the Word Dynamo Challenge, which assesses vocabulary level (starting at elementary school, middle school, high school, or college level) and then gives lists and word studies to improve vocabulary, along with quizzes built into each of the 20 levels. Kids can also create their own lists of words or review the numerous existing lists or search for specific words. Within each list, kids can review the list of words and definitions, do a Quick Study with flashcards, or take matching quizzes on the words and definitions. Based on the Word Dynamo Challenge, kids get recommended lists -- or they can browse all the lists, which are sorted by subjects, grade levels, test prep, and foreign language. Some lists focus on Greek and Latin roots and prefixes and suffixes.
Some moderation of the lists would be helpful to weed out lists that don't need to be publicly accessible, as some lists seem to have been created for joke or shock value (like "bad words" or "sex words"). This powerful tool is tied in to Dictionary.com, which is a powerful resource itself.
Word Dynamo starts with the challenge assessing kids' prior vocabulary knowledge, kids waste no time and get right down to learning challenging words and expanding their vocabularies. The list categories help kids find just the word lists they need and are organized by grade level, subject area, and test-specific preparation, and students can also search lists. After taking the Word Dynamo Challenge, kids will get recommended lists and be able to increase their word score and unlock higher levels by completing the quizzes.