Jeffrey Choppin directs the mathematics education program at the Warner School. Building from his prior teaching experience in the Washington D.C. public schools, during which he was awarded the Presidential Award for Excellence in Mathematics and Science Teaching, he teaches courses for prospective and current teachers that explore the teaching and learning of mathematics at the secondary level. His mathematics methods courses require participants to explore middle- and high-school mathematics topics in ways that emphasize conceptual understanding, connections between different ways to represent mathematical relationships, and the design of instructional tasks, with the goals of developing better understanding of mathematics as well as seeing mathematics from a learners’ perspective. Choppin’s research currently focuses on teachers’ perceptions and uses of curriculum materials in the context of the Common Core State Standards for Mathematics (CCSSM). Choppin’s research also focuses on what teachers learn from using innovative curriculum materials, particularly with respect to teacher knowledge of how the materials develop student reasoning around key mathematical concepts.