The purpose of the study is to identify the classroom mathematical practices developed within a learning environment designed by Realistic Mathematics Education for teaching cone and pyramid to preservice teachers. A teaching experiment including five-week instructional sequence by a hypothetical learning trajectory about the solids of cone and…

It has been common to use video records of instruction in teacher professional development, but participants have rarely been encouraged to evaluate teachers and students' actions in those records, allegedly because evaluation deters from the development of a professional discourse. In this study, we inspected teachers' online discussions of…