While researching your topic you will encounter different types of resources. Keep in mind the types of resources your instructor is requiring. Remember, they are giving you your grade!
How to tell the difference between scholarly and popular sources:
Is your instructor asking for peer-reviewed journal articles? Peer-reviewed is when an author submits an article to a peer-reviewed journal and it is then reviewed by other scholars in the discipline. It is your more academic and scholarly literature. In many databases you can limit your searches to peer-reviewed articles/journals.