Bethany Wilcox is a member of the Physics Education Research group at the University of Colorado Boulder. Her research interests include understanding and addressing students' difficulties utilizing sophisticated mathematical tools and techniques in the context of physics problem solving. In addition to investigating students' difficulties in the context of a single course, she is also interested in understanding how these difficulties change longitudinally as students advance through the curriculum and encounter these mathematical tools in multiple contexts. She is also interested in the development of research-based and validated assessments of student learning that can be used to measure the impact of curricular changes or compare student learning across courses and institutions. In particular, she is utilizing advanced testing theories to explore viable options for creating modular assessments that can address variations in content coverage in across courses.