Most educational software available to children is designed for a single user and this, coupled with a shortage of computers in schools, means that pairs or groups of children often share an inappropriate interface. Previous research has found that this can be detrimental to the process of collaboration. We describe a novel user interface, Separate Control of Shared Space (SCOSS), and present two studies that explore its potential as a tool to resource collaborative interactions. We illustrate how it can be used to allow for equitable control at both input and task levels, and how it visually represents agreement and disagreement which can be used to mediate collaboration about a final, agreed-upon, solution. We conclude by recognising the potential of the SCOSS interface for providing data about each user's input into a learner model, which can then be used as an additional resource for mediating the collaborative process.