This study investigated the ways in which four middle grades teachers developed mathematical knowledge for teaching (MKT) geometry as they implemented dynamic geometry software in their classrooms with the assistance of a coach. Teachers developed various components of MKT by observing coaches teach, by dynamic discourse with students, which is discourse with respect to dynamic geometry software images, and by discussions with coaches. The dynamic geometry software environment proved productive as coaches guided teachers’ growth in explanations, examples, and definitions. The environment also helped teachers discover unnoticed abilities among their low achievers. Moreover, teachers developed confidence to teach with more expert uses of dynamic geometry software.

中文翻译：

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通过在动态几何软件环境中进行辅导来促进教师进行几何推理

本研究调查了四名中学教师在教练的协助下在课堂上实施动态几何软件时，如何开发用于教学 (MKT) 几何的数学知识的方式。教师通过观察教练的教学、与学生的动态话语（即关于动态几何软件图像的话语）以及与教练的讨论，开发了 MKT 的各个组成部分。随着教练指导教师在解释、示例和定义方面的成长，动态几何软件环境证明是富有成效的。环境还帮助教师发现低成就者中未被注意的能力。此外，教师培养了信心，以更专业地使用动态几何软件进行教学。