This chapter explores the entanglement of research and practice, offering an account of science|arts practice in which research-driven "features of creative pedagogy" were used within an action research project to engage young people with the problem of ocean plastics. Thinking with Barad's theory of agential realism, we explore the ongoing emergence of new matter and meaning for the young people, teachers and researchers engaged in this transdisciplinary practice-research.One component of a large H2020-funded project exploring creativity in science/arts transdisciplinary practices across Europe was a study of action research in six UK secondary schools with science/art teacher pairs. This chapter draws on research conducted within one school in which the issue of plastics in the ocean was explored with 52 students aged 14-15 within an "arts-science project", to develop the young people's ideas about environmental responsibility understood, explored and expressed together through science and art.An approach to researching emergent and creative pedagogies which brings agency to the fore within a material-dialogic, intra-active understanding of (post)human creativity was used. Data gathered through mixed methods, including questionnaires, interviews and photographs, and selected via "glow moment" assemblages, were analysed with and through theory using diffractive analysis to iteratively unfold data, theory, research and practice. This stance embodies a material-dialogic approach, with research, theory and "data" in dialogue.In the chapter, a sequence of diffractions is described, responding to initial questions posed by the book editors: "When/where/how do objects/subjects of inquiry, and embodiment, come to matter in STEAM (re-)configurings in practice?" These diffractions unfold the emergence of matter and meaning through intra-active material dialogue in a science|art practice, raising questions from/for practice about the concept of ethics, trusteeship and responsibility in environmental education.