The document describes the Learn3 system created by GTI at UPF for authoring and sharing learning designs. It provides an overview of the system's current version and capabilities, which allow for social sharing, co-editing of designs using three integrated editors, and commenting on designs. Two use case scenarios are presented: one for collaborative work between biology teachers at multiple disciplines, and a second for a community of high schools sharing biology learning designs. More information on demonstrations, papers, and the system's evaluation are provided at the end.