The role of the interface in structuring student learning and in directing the learner’s cognitive effort toward relevant material has become increasingly centralised in recent years. Specifically, interface designers have been called on to design interfaces which keep the learner focused on or “engaged” in the domain material, with the view that such engagement will have learning benefits. In this paper we operationalise the notion of cognitive engagement in terms of familiar cognitive psychological principles: planning and learning. Following laboratory studies, we have taken the view that cognitive planning can be induced by increasing the “cost” of selecting and executing actions by designing less direct interfaces. A study is reported which contrasts direct and indirect manipulation interfaces for a constraint-based planning task. Results from the study suggest that manipulation style can indeed affect users’ information search and task solution strategies.