In this investigation I focused on a process of activities of a particular group of teachers and learners. Basic skills in mastering mathematical concepts were addressed. The focus was on concept formation in the geometry classroom. The methodology involved an educational case study as a form of inquiry to investigate spatial sense. Evidence was obtained regarding mathematics teachers' and mathematics learners' knowledge of space and shape. Problems experienced in concept formation in geometry were investigated and analysed. An account is provided of how teachers and learners responded to problems related to space and shape. Information about the mathematical performance of a group of mathematics teachers and mathematics learners is organised, interpreted, and evaluated.