For years our children have benefited from using Vocabulary Workshop published by Sadlier-Oxford. The paperback workbooks teach new words through definitions, antonyms, synonyms, word associations, and reading comprehension exercises. Repetition allows students to achieve success and higher retention.
Students, elementary through high school, needing additional practice can access additional online review activities for every level workbook. Auditory recordings of the word pronunciations and definitions are available. These online exercises are especially helpful for students who need auditory input for optimal retention.
Online link http://www.sadlier-oxford.com/vocabulary/iwords.cfm?sp=student&level=A#unit2