Keep an index card box next to the Writing Center. When students are writing and come across words that they've already used, and would like synonyms for, they can look them up in a thesaurus file, where words are kept in alphabetical order. In order to start the thesaurus, students may have to look up words in a thesaurus, ask classmates, or even you. But once it gets going, it will be a valuable tool for your class. It will also encourage them to learn new words instead of using the words they are already familar with, and their vocabulary will increase.