MyVocabulary.com offers 14 PREFIX puzzles with the grade level of each word marked to the right of the word beginning with a prefix. Use eight grade level words for each prefix."UN" prefix words: Unattractive - 8, Unconscious - 6, Unfinished - 6, Unidentified - 7, Unnecessary - 6, Unpredictable - 7, Unravel - 5, Unworthy - 8