Abstract This mixed methods study examined the impact of two design strategies on interactional processes in a collaborative tangible-tabletop land-use planning simulation. Twenty pairs of fifth grade children used the simulation to create a world they would want to live in. To investigate the impact of positive interdependence half the pairs were assigned one of two roles, each with an associated set of tangible ‘land-use’ stamp tools. All pairs were given access to pause and reflect tools. Quantitative results showed that children in the positive interdependence condition gave more one-way explanations to their partners than control pairs. They also had fewer but longer instances of bilaterally resolved conflict. Qualitative findings indicated the importance of pause and reflect tools for provoking explanations and resolving conflict. This study has revealed important considerations for the instantiation of positive interdependence and reflective pauses in collaborative tabletop learning systems, showing both quantitative and qualitative differences in the interactional processes that result from these design strategies. CCS CONCEPTS. Human-centered computing → Empirical studies in collaborative and social computing.