A deep body of literature supports the notion that learner-centered, interactive teaching practices can improve student learning (Bransford, Brown, and Cocking 1999). Endorsements in the literature for a wide range of active learning strategies in economics courses suggests that faculty are amenable to moving beyond chalk and talk. Yet, research-based evidence demonstrating the effectiveness of such practices in economics is limited and it is mixed. Becker (1982) suggests a plausible explanation for varied results. If classroom innovations decrease the costs of knowledge acquisition, students may reallocate the time gains to nonacademic pursuits. Because pedagogic innovations are costly to instructors and their impact on student learning is uncertain, it is not surprising that instructors may be reluctant to adopt new approaches (Watts and Becker 2008).An alternative to modifying teaching practices is to modify assessments to foster improved student engagement. Students may vary the intensity and approach to studying according to factors such as the format of assessment (Scouller 1998) and often behave strategically, allocating time and attention based on expectations of what will be assessed and how to earn strong grades. Because course assessments often frame and orient learning behaviors, Gibbs (2006) argues that assessments may have more impact than teaching on learning outcomes. Scouller and Prosser (1994) suggest that assessment may be the most important factor influencing student learning.We present an alternative method for motivating student learning, the "challenge quiz," that builds on the benefits of essay-based assessment and mastery learning and testing. Because our method employs a blended formative/summative assessment tool rather than pedagogic practice, it avoids the potential substitution of student time toward other pursuits. The selective and limited nature of the assessment also avoids imposing an excessive grading burden on instructors.