Though this article is focused on push notifications about U.S. politics from U.S. mainstream media, the lessons to be drawn are, I think, more widely applicable. Take the time to read the sample notifications. I think that if you study anything - yes, including math and science - you're going to get a similar range of perspectives (this certainly applies in the field of ed tech). Some sources are inherently untrustworthy, some sources focus on specific types of stories, some sources have a certain point of view, and some sources are generally reliable (but with some glaring blind spots). You should never depend on any one source, and you should eliminate sources reluctantly, because even the propagandist is right once in a while.