The primary measure used to determine relative effectiveness of in-class activities has been student performance on pre/posttests. However, in today's active-learning classrooms, learning is a social activity, requiring students to interact and learn from their peers. To develop effective active-learning exercises that engage students, it is important to gain a more holistic view of the student experience in an active-learning classroom. We have taken a mixed-methods approach to iteratively develop and validate a 16-item survey to measure multiple facets of the student experience during active-learning exercises. The instrument, which we call Assessing Student Perspective of Engagement in Class Tool (ASPECT), was administered to a large introductory biology class, and student responses were subjected to exploratory factor analysis. The 16 items loaded onto three factors that cumulatively explained 52% of the variation in student response: (1) value of activity, (2) personal effort, and (3) instructor contribution. ASPECT provides a rapid, easily administered means to measure student perception of engagement in an active-learning classroom. Gaining a better understanding of students' level of engagement will help inform instructor best practices and provide an additional measure for comprehensively assessing the impact of different active-learning strategies.