A large percentage of litigation arising out of contracts results from poor drafting. In order to eliminate this litigation, it is imperative that students and legal professionals master good drafting skills. One of the most important aspects of drafting a contract is the operative language--language that affects legal relationships. This lesson is designed to introduce law students to operative language commonly used in drafting contracts, in particular, language of obligation (shall), language of authorization (may) and language of condition precedent (must). The lesson begins with a segment explaining each of the three categories of operative language followed by exercises which permit the student to apply his or her understanding of proper usage of that category. The lesson concludes with a segment of general exercises that test whether students have mastered the distinctions among the different categories of operative language.