In their Young Mathematicians at Work series, Catherine Twomey Fosnot and Maarten Dolk described Mathematics in the City, an innovative project where teachers helped young children construct a deep understanding of number and operations in a math workshop environment. Now they and two colleagues from the project have developed a 21st-century approach that provides pre- and inservice teachers with an interactive, video-based, digital context for inquiry into the teaching and learning of mathematics.

Designed for workshop participants and preservice teachers, the Addition and Subtraction Minilessons CD-ROM offers users a multi-media learning environment for professional development on topics ranging from instruction to assessment, and that stimulates action, reflection, and discussion with dynamic video clips, children's work samples, and interviews with students and teachers.

In Addition and Subtraction Minilessons clips of real teachers conducting effective minilessons in real classrooms show you how these short, focused sessions can build big mathematical thinking in young learners.

Users also study teachers at work: designing rich contexts for problem-solving; drawing connections between mathematical ideas and strategies; and developing a vibrant mathematical community.