This article examines whether an analysis of student answers to a standards-based, summative examination can be used to improve a teacher's instruction. The author, who is a chemistry teacher at Saratoga Springs High School, analyzed both the multiple-choice and the constructed response questions of the June 2003 New York State chemistry exam focusing on the items that were heavily missed by his students. A total of 44 exams were analyzed from two classes of students. An analysis of two of the multiple-choice and two of the constructed response questions is presented. Based on an analysis of the students' answers, the author learned that a final exam can be used to improve instruction and not just as a "summative" measure of achievement.