Teach your students how prefixes drastically change the meaning of words and allow readers to unlock many new words and add them to their vocabulary. The first page in this unit is a list of 10 prefixes, their definitions, and example words using each prefix. In the next activity, Pick a Prefix, students work in pairs trying to identify more words than their opponent using the prefix on the task card. Cards are included in for a whole class game called Guess the Prefix. A crossword puzzle provides independent practice. Cards are provided for "I Have, Who Has" activity, reviewing all of the prefixes. That unit concludes with a comprehensive test. Part One of the test involves matching the definitions with a prefix. Part two of the test requires application and using the prefixes in context.