Research has been conducted on the role and importance of visualisation in many fields, including
psychology, but very little has been done to extend its role to mathematics education in particular.
Furthermore, much research has been done on the importance of critical thinking. However, to date
not much has been done to clarify the fact that visualisation is a very important component of
critical thinking. In this paper I investigate visualisation for the purpose of examining its role in
developing critical thinking for a better understanding of mathematics by Grade 9 learners. In
order to achieve this, I provide a qualitative examination from a master’s dissertation of some
thought processes used during visualisation when Grade 9 pupils engage in mathematics tasks. In
order to support the derived thought processes data, audio taped interviews were conducted with
the students. A framework of four stages of visualisation was adapted for the collection and analysis
of data. Several roles of visualisation were identified, which revealed that visualisation encourages
critical thinking which further leads to a better understanding of data handling.