Context clues are clues or hints that help identify unknown words in a sentence. In teaching context clues, it is important to encourage students to work together to find the meaning of an unfamiliar word. Context clue exercises are not only fun, but are very useful in the development of a child's vocabulary. Challenges should be done where the students are not allowed access to dictionaries
. and/or glossaries. A great example of a context clue challenge and some more information on teaching context clues can be found here: http://www.brighthub.com/education/k-12/articles/6323.aspx