Margaret Smith holds a joint appointment at the University of Pittsburgh as professor of mathematics education in the School of Education and as Senior Scientist at the Learning Research and Development Center. Her research focuses on what teachers learn from the professional education experiences in which they engage. Jennifer Cartier is the director of teacher education and a member of the science education faculty at the University of Pittsburgh. Her work focuses on the design and facilitation of learning contexts for pre-service and early career teachers. Mary Kay Stein holds a joint appointment at the University of Pittsburgh as professor of learning sciences and policy and as Senior Scientist at the Learning Research and Development Center. Her research focuses on mathematics teaching and learning in classrooms and the ways in which policy and organisational conditions shape teachers’ practise. Danielle K. Ross is a teaching fellow and doctoral candidate in science education at the School of Education of the University of Pittsburgh. Her work focuses on teacher learning and the design of learning contexts for beginning teachers. She was previously a biology and ecology teacher at Leechburg Area School District in Leechburg, Pennsylvania.