<p><strong>It was April 2017 and Philippa was sitting in the audience at a popular conference for teachers when she realised that she was bored. So begins the origin story of this unconventional research and its consequent thesis. Through seeking to challenge the traditional ‘sit and get’ model of conferences for teacher professional learning and development (PLD), the collective, board game-like activity, named Plan D, emerged. While acknowledging that traditionally-designed conferences do have the potential to be effective models of PLD according to the literature on teacher PLD and teacher learning, this research wonders what might happen when teachers design their own conference as and for – posed as a dialectical relationship in this thesis: as | for – PLD. Plan D then, was created in an attempt to nurture and empower teachers to design their own conference for PLD purposes. The intention was for Plan D to support both the creation of a conference design (the d.conference): designing a conference for PLD; but through teachers playing Plan D, they are also invited to consider what constitutes effective PLD: designing a (d.)conference as PLD.</strong></p><p>Drawing on Carol Taylor’s concept of knowledge-ing and also on Baradian and Deleuzoguattarian philosophical constructs, this thesis-story is told through three voices: that of Philippa as becoming-researcher; that of Plan D as becoming PLD-model; and that of the entangled, mutually co-constitutive ‘us’. Positioned as a complexity (thinking)-infused feminist new materialist, posthuman, postqualitative study, this research places some traditional concepts of qualitative research sous rature, including methodology and data. Rather, methodology is conceptualised as emergent and data are seen as agentic with the power to glow. This research suggests that through playing Plan D as becoming PLD-model, teachers are simultaneously invited into and create a space of | for knowledge-ing through the material presence of Plan D, which is understood as an agentic, vital, more-than-human other. This space of | for knowledge-ing is conceptualised as a plenum: a space full of matter, a space ripe with potential for knowledge-creation. It is through intra-actively playing Plan D, in the context of the teachers’ unique and dynamic assemblages, that knowledge-ing emerges. The space of | for knowledge-ing, and its intra-active relationship with play in the context of teacher PLD, is the key argument of this thesis. Additionally, a further knowledge-ing contribution emerges through the unfolding of the research and this thesis-story itself: play and its intra-active, affective companion wonder is positioned as a potentially powerful force in research.</p>