Investigating disengagement is a continuing concern within computer-based learning environments. Drawing upon several strands of research into preservice teacher learning with network-based tutors, this paper outlines an object orientation to conceptualize a type of disengaged behaviour referred to as carelessness. We further differentiate this construct in terms of carelessness towards one’s own learning as opposed to other’s learning. In support of our claims, we review research into carelessness in the context of nBrowser, an intelligent web browser designed to support preservice teachers learn about the pedagogical affordances of novel technologies while designing lesson plans. The key aspects of this research can be listed as follows: (1) a knowledge engineering approach to implement a set of production rules within the learning environment to detect instances of carelessness and intervene; (2) a data-driven approach to infer learner behaviours in their absence due to carelessness; and (3) a model-driven approach to improve the functioning of the learning environment despite instances of carelessness. We discuss the limitations of these different approaches and draw implications for future research into preservice teacher disengagement with computer-based learning environments.