Rapidly changing domains of contemporary art practice are currently exerting new pressures on teacher pedagogy and student learning in visual arts education. Relational art, as conceptualised by Nicholas Bourriaud (2002) in his book Relational Aesthetics, represents one such domain that is proposed as a new area of study in the New South Wales' senior Visual Arts curriculum. Relational art practice means students and teachers encounter artworks as ‘interstices’, or sites of exchange. Artists, acting as ‘semionauts’, implicate audiences as participatory travellers in navigating non-traditional boundaries of form, space, time and history. While art theorists have discussed the complexities of relational forms of practice in art, there exists limited empirical support for informing teachers about how students conceptualise relational art practice and implications for pedagogical practice. This presentation outlines a study that addressed this gap in art educational research. Drawing on the theoretical framework, design and methods of earlier research by Maras (2010) which mapped developmental differences in the theoretical bases of younger and older students’ critical reasoning about artworks during middle childhood, the study sought to extend on these findings to investigated the extent to which developmental differences occurred in the theoretical bases underlying younger and older middle school students’ critical reasoning in art. The study involved one Year 8 Visual Arts class and one Year 10 Visual Arts class. Digital recordings of collaborative classroom discussions in two consecutive critical study lessons for each class were made and transcribed. Conceptual analysis of the data revealed the extent to which conceptual patterns were established and maintained in collaborative interpretations of relational artworks. Of particular focus was how concepts were broached, collectively elaborated, recursively transformed and applied in the collective reconceptualization of artwork meaning among the teacher, students and their peers. Findings of the study showed that although both groups of students conceptualised the meaning of relational artworks in intentional terms as objects that functioned within the artworld as a social reality, the older students demonstrated higher levels of conceptual integration in their collective reasoning. The extent to which the collective intentionality was implied within preferred pedagogical conventions adopted by the teacher contributed to students’ learning in art criticism was also revealed. The demands relational artworks as participatory sites of exchange make on students’ interactions and teacher’s interventions in the classroom context revealed some of the more interesting challenges art educators face when teaching relational art practice.