We seek to establish a new model for online educational communities, based less on the digital library model of information gained by searching a collection. Instead, we focus on the value added by community-driven content through members' discussions, reviews, and ratings of content items. To gain critical mass for community input, we must actively lower barriers to participation by disseminating information from both the content and the community into the notification streams that community members routinely use. This includes traditional dissemination mechanisms (web-sites for collections, forums, email, and online blogs and newsletters for notification) and newer notification streams (social networking sites where users can subscribe to receive notification as part of their everyday online life). Our target educational community is the AlgoViz project (http://algoviz.org), which aims to promote the use of Algorithm Visualizations (AVs) in the classroom. Despite being widely viewed as potentially improving CS education, the rate of AV use has progressed little from the mid 1990s. Known impediments could be overcome if existing knowledge about best practices in AV use were distributed by an effective community of AV developers and users. Improved AV use in the classroom potentially affects the educational outcomes for tens of thousands of students every year. A clearinghouse of available AVs, with community-based rating and review, and interaction between users and developers, will make it easier for instructors to adopt quality educational materials. Our techniques for lowering barriers to contributing user-driven content to educational collections should be applicable to many educational communities.
