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."SUB" prefix words: Subconscious - 8, Subdue - 7, Submarine - 6, Submission - 8, Subscribe - 7, Substance - 6, Subterranean - 6, Suppress - 7