This book employs a set of theoretical frames to reveal a panorama of research findings having potential interest for educational researchers, policy makers, teacher educators and K-12 teachers. It maintains that ideal science classrooms feature creative and inquisitive students working together to solve problems that interest them. More learning occurs at centres of high pupil density and students who participate most in on-task activities are not necessarily those who contribute or learn most. The book identifies weaknesses of assessment based on products only, and highlights the advantages of using videotapes as sources for assessment. Roth shows that student learning is not only a result of individual sense-making efforts but involves interactions between living and artifactual components of a community of participants.