The transformation of natural history and science museums from receptacles (temples) to facilitators (forums) of knowledge fosters discourse around issues relating to science and society, known as social scientific issues (SSI). To assist guests with enhanced object-based learning, extended reality (XR) technologies are thought to leverage the leisure and social motivations of guests for greater object-based learning and SSI engagement. To model guests' experiences using XR, this theoretical paper identifies and describes how a new conceptualization of Cultural-Historical Activity Theory (CHAT) to facilitate SSI outcomes through shared outcome spaces of interacting guest and museum activity systems, mediated by XR technology. We present two scenarios of forum-forward SSI-based learning utilizing this emergent CHAT model in: (i) scrutinizing the environmental and ecological consequences of human activity and (ii) unveiling the contributions of Indigenous Science Knowledge. Issues surrounding ownership and representation are discussed when 'transforming' singular objects into digital, decontextualized, and distributable entities.