Knowing basic prefixes gives clues to the definitions of over 1,500 words! Introduce your middle or high school students to 13 common prefixes (like pre, dis, and semi) with the help of this packet. Students start by using context clues to define the given prefix in each sentence. After they define each of the prefixes, give them the dictionary definitions before they continue working on the three exercises that follow. In the first, they'll match the prefix and its definition; in the second, they'll combine prefixes with different roots to make words; in the third, they'll complete sentences with the correct prefix. Answers are provided on the last two pages.