Think about these questions. You don't have to post answers, but you can if you want. The questions are meant for Americans, but you can adjust them to fit your country.
How many famous people from China can you name?
How many Civil War generals (four generals from an important conflict in your country's history) can you name?
How many of the Founding Fathers (four people who wrote your country's constitution and/or fought for its independence) can you name?
How many governors of US states (heads of state from small neighboring countries) can you name?
How many living Nobel Prize winning scientists can you name?
How many current heads of state can you name?
How many authors, composers, or artists, outside of your own cultural heritage, can you name?
I know that being able to list random facts is not true knowledge. But it often serves as a good indication of how much you care about understanding the world you live in. At least four in each category is very good.