What distinguishes Sarah, and to some extent Debbie, from the other students is the recognition of proof as a part of mathematics rather than as optional extra. It is as though both seek to grasp the idea" expressed by Raman (2003). Debbie, for example, refuses to "let things go," telling a story of persistence in the face of finding her studies difficult, of how she refused to give up and of how she demanded help from an otherwise aloof tutor: