FactCheck is a project of the Annenberg Public Policy Center. They state their mission as follows: "We are a nonpartisan, nonprofit “consumer advocate” for voters that aims to reduce the level of deception and confusion in U.S. politics. We monitor the factual accuracy of what is said by major U.S. political players in the form of TV ads, debates, speeches, interviews and news releases. Our goal is to apply the best practices of both journalism and scholarship, and to increase public knowledge and understanding."
Their website includes articles, checks on news stories, and quizes.