This book reports the accounts of researchers investigating the eighth grade mathematics classrooms of teachers in Australia, China, the Czech Republic, Germany, Israel, Japan, Korea, The Philippines, Singapore, South Africa, Sweden and the USA. This combination of countries gives good representation to different European and Asian educational traditions, affluent and less affluent school systems, and mono-cultural and multi-cultural societies. Researchers within each local group focused their analyses on those aspects of practice and meaning most closely aligned with the concerns of the local school system and the theoretical orientation of the researchers. Within any particular educational system, the possibilities for experimentation and innovation are limited by more than just methodological and ethical considerations: they are limited by our capacity to conceive possible alternatives. They are also limited by our assumptions regarding acceptable practice. These assumptions are the result of a long local history of educational practice, in which every development was a response to emergent local need and reflective of changing local values. Well-entrenched practices sublimate this history of development. The Learner's Perspective Study is guided by a belief that we need to learn from each other. The resulting chapters offer deeply situated insights into the practices of mathematics classrooms in twelve countries: an insider's perspective. The Project The Learner's Perspective Study aims to juxtapose the observable practices of the classroom and the meanings attributed to those practices by classroom participants. The LPS research design documents sequences of at least ten lessons, using three video cameras, supplemented by the reconstructive accounts of classroom participants obtained in post-lesson video-stimulated interviews, and by test and questionnaire data, and copies of student written material. In each participating country, data generation focuses on the classrooms of three teachers, identified by the local mathematics education community as competent, and situated in demographically different school communities within the one major city. The large body of complex data supports both the characterisation of practice in the classrooms of competent teachers and the development of theory.