Sometimes courses with large enrollments spawn useful innovations, and this study looked at one empirically. Large courses almost always mandate the use of multiple-choice tests, and incorporating quizzes in these courses can present sizeable logistical challenges. To cope with that situation in a large microbiology course, the faculty involved here developed an online multiple-choice question (MCQ) authoring, testing, and learning tool they dubbed Quizzical. Students in the course used the tool to write MCQs that were then used as quiz questions. The research explores how use of Quizzical affected performance in the course.