The COVID-19 pandemic has led us to an unanticipated and challenging world. In educational settings, one of the ways to respond to this crisis has been the online delivery of content. One of the valid critiques of these online delivery models is the passive role of the participants. The challenge is we still know very little about how technology could support children’s active participation in their learning. This challenge exacerbates with children in early years and in their home setting, which is the focus of our research at Monash University’s Conceptual PlayLab. This paper reports on solving the theoretical problem of digital design that can create a relational space for children’s STEM concept formation. The paper argues that engagement with digital tools demands clear design principles that could support both robust concept formation and also development of learning motives in children. Drawing on Wartofsky’s work on artefacts and tool-use and (Fleer 2017a, 2019), conceptualisation of “digital coadjuvant”, we make a case that technology offers a transformative potential for children to imagine and explore together with their caregivers in the Conceptual PlayWorld. We have showed through a practice example on how person and digital technologies become mutually constituted in a pop-up Conceptual PlayWorld. The design principle highlighted in the paper argues for transcending the binary of digital and non-digital. The paper concludes that Conceptual PlayWorld offers a design model that uses digital tools to sustain and amplify children’s exploration in their imaginary play situation.