- Instructive function. Some media outlets exist to cultivate knowledge by teaching instead of just relaying information. Major news networks like CNN and BBC primarily serve the information function, while cable news networks like Fox News and MSNBC serve a mixture of informational and interpretation functions. The in-depth coverage on National Public Radio and the Public Broadcasting Service, and the more dramatized but still educational content of the History Channel, the National Geographic Channel, and the Discovery Channel, serve more instructive functions.