Determining purpose is perhaps the most challenging category to determine.
Sticking to information out of more professional or scholarly sources will help.
Think about all of the potential reasons information may have been produced:
Can you look at the information or the source of the information and see a distinct audience for it?
How do you determine is something is biased?
Consider materials that are created to entertain, offer humor, or satire. Websites like the Onion create authentic-appearing news stories that are meant to help us laugh at current events, society, and politics. It's unfortunate when these materials are mistaken for truth.
What is the role of news satire in our modern society?
How can you avoid being duped into believing satirical news is truth?