Wendy Aaron is an assistant professor in mathematics education. Her interests involve secondary mathematics instruction and practice-based teacher education. She is interested in how prospective teachers can be supported in learning how to do ambitious teaching. Toward this end I have worked with the Geometry Reasoning and Instructional Practices research group at the University of Michigan in the development of LessonSketch (www.lessonsketch.org) an online environment for practice-based professional development which allows users to study and create representations of instruction.