Currency: The timeliness of the information.
Relevance: The importance of the information for your needs.
Authority: The source of the information.
Accuracy: The reliability, truthfulness and correctness of the content.
Purpose: The reason for the information to exist.
Just because you find something on an .edu website doesn't mean that it is scholarly research from a credible scholar. Opinion and student-created content can be posted on .edu websites which are owned by educational institutions of all levels.
Evaluate all website content regardless of domain.
When you find a good, scholarly website with a bibliography of solid sources, follow the cited sources for additional information. Many university departments and academic libraries offer annotated bibliographies of scholarly websites in a particular field.