It is widely accepted that mathematical learning builds upon students' prior knowledge and understandings, and their identities. In this study, this phenomenon is explored with indigenous students in remote community schools in outback Australia. Through one-on-one task-based interviews, it was found that these students had some clear understandings of the measurement concepts involved, although these understandings were often idiosyncratic to these students in this context. The task-based one-on-one interview gave better insights into students' knowledge than the written form of the National Assessment Program-Literacy and Numeracy assessment. Nevertheless, the students' conceptions provide a useful basis upon which to build subsequent knowledge, understanding and skills in the forms required by the formal mathematics curriculum.