Teaching world history is challenging. In addition to covering the history of the world geographically and chronologically, it is difficult to find high quality, translated materials ready for classroom use. The Roy Rosenzweig Center for History and New Media at George Mason University offers free, online materials, including primary sources, teaching strategies, and lesson plans, designed to facilitate world history teaching. World History Matters provides a portal to seven websites that address world history broadly as well as through specific topics such as the French Revolution, the Soviet Gulag, and the history of 1989. These free, educational projects are designed to help teachers and students locate, analyze, and learn from primary sources to explore the complexity of the past. Collectively, while emphasizing historical thinking skills, they focus on comparative issues and global forces that transcend individual societies such as trade routes, technology diffusion, migration, and disease transmission.