The purpose of this article to describe a model of mathematical learning and caring relations, where "caring" is conceived of as work toward balancing the ongoing depletion and stimulation involved in student-teacher mathematical inetraction. The author considers reasons for building the model (why) to be satisfied by this brief introduction - to understand and account for mathematical learning and caring relations. He situates the model in school classrooms (where), and he intends the model to be about the learning of pre-adult students as well as their teachers (who), although his comments may have wider applicability. Having briefly addressed why, where, and who, in the first two sections he focuses on "what": what he takes to be acts of mathematical learning; what students and teachers learn; and what he defines as mathematical caring relations. In the third section he focuses on "how": how students ad teachers learn what they learn; and how they can engage in mathematical caring relations. He concludes the paper by describing some benefits of a model that holds learning and caring together.