The Chicago Guide to Fact-Checking by Brooke Borel offers scenarios to practice fact checking. Here's an example:
"Think Like a Fact-Checker: The next time you read a magazine article, mark all the numbers. Can you track down reliable primary sources for each one? Which number proved the most difficult to check, and why do you think that is?"
If you'd like more practice, check out the book.
The Chicago Guide to Fact-Checking by