Hourcade, Juan PabloBederson, Benjamin B.Druin, AllisonCollaborating in small groups can be beneficial to children's learning and socializing. However, there is currently little computer support for children's collaborative activities. This was our motivation for building KidPad, a collaborative storytelling tool for children. KidPad provides children with drawing, typing, and hyperlinking capabilities in a large, two-dimensional canvas. It supports collaboration by accepting input from multiple mice. In building KidPad, we developed solutions to problems common to all single-display groupware applications for children: obtaining input from multiple devices, and using an intuitive user interface metaphor that can support collaboration. Our solution for obtaining input from multiple devices was MID, an architecture written in Java. We addressed the need for an appropriate user interface metaphor byusing the local tools metaphor. This paper describes our work on MID and local tools in the context of building of KidPad, and aims to provide developers with valuable insights into how to develop collaborative applications for children. (UMIACS-TR-2003-44) (HCIL-2003-18)en-USTechnical Report