Rachael M. Welder is an Assistant Professor of Mathematics Education at Hunter College of the City University of New York. She earned a Ph.D. in Mathematics, with specialization in Mathematics Education, from Montana State University. Her research focuses on preservice elementary and middle grades teachers and their development of mathematical content knowledge for teaching. She is especially interested in cultivating teachers' content knowledge in ways that will help them link arithmetic and algebra instruction and promote students´┐Ż algebraic thinking.

Linda M. Simonsen is a Professor of Mathematics Education, in Science and Technology at the University of Washington at Bothell. Her interests include making effective use of different modes of delivery to teach mathematics to diverse learners. In support of this objective, her research focuses on the nature and quality of mathematical discourse in on-line settings.