Chronic student disengagement with mathematics is considered a key problem in Australia. A decreasing number of students are undertaking mathematics, critically limiting Australia’s mathematically skilled workforce. Mathematics disengagement is observed even early in formal learning, which is potentially problematic for both conceptual foundations and long-term engagement. Many young students do well in mathematics through memorisation without conceptual understanding. Later, when flexible or deeper knowledge is needed, the students have little to draw on and can become frustrated and disconnected. Inquiry-Based Learning (IBL) has shown potential for increasing several dimensions of mathematics engagement at the primary school level. IBL is a pedagogical approach in which students address complex problems and are supported to negotiate problem meaning, plan and conduct investigations, and put forth defensible conclusions supported by mathematical evidence. Although mathematical inquiry has demonstrated potential to both strengthen children’s engagement and foundational understanding, there is little to suggest what specific aspects of inquiry serve to engage or re-engage students with key mathematical concepts. Expectancy-value theory (Eccles & Wigfield, 2002) provides a framework through which interactions between children’s beliefs about their mathematical competence, expectation of success, difficulty of a task and perceptions of task value are able to be examined--for example, helping to explain how students’ expectations of success and their valuing for specific tasks in STEM areas are associated with their motivation to engage in a task. In this paper, Eccles and Wigfield’s expectancy-value model has been adopted as a lens to examine a geometry unit using mathematical inquiry in a class of Year 5 students (ages 9-10). The research question under investigation was What aspects of inquiry-based learning support primary students’ motivation and engagement in mathematics? The lessons were videotaped, and along with field notes and student work samples, subjected to theoretical coding using Eccles and Wigfield’s model. Although limited in scope, the results provide insight into identifying features of IBL that may be instrumental to bringing about increased motivation and engagement by students in mathematics. Identifying potentially motivating aspects of IBL enable these to be integrated and more closely studied in both IBL practices and other, more routine aspects of mathematics teaching and learning.Eccles, J. S., & Wigfield, A. (2002). Motivational beliefs, values and goals. Annual Review of Psychology, 53, 109-132.