1 TEACHING METHODS COMPARISON IN A LARGE CALCULUS CLASS Warren Code, Costanza Piccolo, David Kohler, Mark MacLean University of British Columbia We report findings from a classroom experiment in which each of two sections of the same Calculus 1 course at a North American research-focused university were subject to an “intervention” week, each for a different topic, during which a less-experienced instructor encouraged a much higher level of student engagement, promoted active learning (answering “clicker” questions, small-group discussions, worksheets) during a significant portion of class time and built on assigned pre-class tasks. The lesson content and analysis of the assessments were informed by existing research on student learning of mathematics and student interviews, though the interventions and assessments were also intended to be compatible with typical course practices in an attempt to appeal to practitioners less familiar with the literature. Our study provides an example of active learning pedagogy (including materials and assessment used) for students at this level of mathematics in a classroom of over one hundred students, and we report improved student performance – on conceptual items in particular – with a switching replication in that each section outperformed the other on the topic for which it received the intervention. Key words: Calculus, teaching experiment 1 Introduction Motivation for this study began with a desire to improve the learning experience for students studying calculus at the North American research-focused institution where it took place: would it be possible to use research-based, high-engagement teaching methods to help students master the conceptual and procedural aspects in the curriculum of a relatively standard differential calculus course? The calculus course under study has a diverse audience in terms of mathematical background and interest consisting primarily of Commerce and Economics students. Though terminal for many of the Commerce students, it is equivalent in course credit to the more traditional, science-oriented calculus course in the same department with much of the syllabus in common with Calculus 1 elsewhere in North America. Despite local pressure to examine teaching methods, traditional lecture remains the (nearly) uniform choice for instruction. On a broader scale, our work was motivated by a demand for empirical study of less traditional, but evidence-based, instruction for introductory undergraduate calculus; the relative dearth of empirical “classroom-based intervention” studies in mathematics education has been summarized by Stylianides and Stylianides (2013). Epstein (2013) published a pioneering study of undergraduate calculus instruction that supports the greater effect of interactive engagement based on the Calculus Concept Inventory, a broad test of core concepts – our study may be considered a further investigation of effects on student reasoning resulting from interactive engagement in a large class setting (100-200 students), as well as further detail for a pair of topics (100-150 minutes of class time each) in terms of the approach to lesson development and deployment of assessment items to expose student thinking at different points in time.