To critically evaluate content on the web (or anywhere,) these are some  questions you might ask:

  • Who created this content and what was their purpose? What can you tell about their point of view?
  •  What claim(s) are they making?
  •  When was this content created, and does its recency affect its validity?
  • How was this content created? What was the process for creating it?
  • What is the platform's source of funding, and does it have a connection to the the claims made?

Four Moves and a Habit
    
From Mike Caulfield, author of Web Literacy for Student Factcheckers 
     What do you do when you see content on the web and you're not sure if it's accurate?  You can use four moves to quickly find more information. 

  • Check for previous work: Look around to see if someone else has already fact-checked the claim or provided a synthesis of research.
  • Go upstream to the source: Go “upstream” to the source of the claim. Most web content is not original. Get to the original source to understand the trustworthiness of the information.
  • Read laterally: Read laterally. Once you get to the source of a claim, read what other people say about the source (publication, author, etc.). The truth is in the network.
  • Circle back: If you get lost, hit dead ends, or find yourself going down an increasingly confusing rabbit hole, back up and start over knowing what you know now. You’re likely to take a more informed path with different search terms and better decisions.

     Source:  Four moves. Web literacy for student factcheckers. 

A habit:

 

Tools for fact-checking:

   There's no one single path to checking web content, but there are a variety of tools that can support you in evaluating claims. See below for a non-comprehensive set of tools. 

Fact-checking websites:
A good fact-checking website will show their sources and explain how they arrived at their conclusions 

Reverse image searching:
Want to see if an image actually depicts a breaking news event, or find the original context for an image? You can trace an image back to its orginal internet source using reverse image searching

Web history:
   
Did you encounter a 404 message or another error message while tracing the source of a claim? Want to check for edits to a website? Check Internet Archive's Wayback Machine for archived versions of the website. 

Use Ctrl+F to look for the context of a claim:
Want to see more context for why a claim is made in a headline or a title? Using the Control+F (find) functionality can point to the context for a claim and let you assess its accuracy. It may also point you to linked sources or footnotes.  
   Note: On a Mac, use Command+F; on a mobile browser, use Find on page