I'm always amazed at surveys like this. In this case, the survey focuses on asking foreigners questions about the USA like the location of states as though that information is something important for them to know. Let's face it, many Americans can't name all 50 states or place them on the map.
For those who have been critical of foreigner's knowledge of the USA, I'd say there are a lot of things that others might view you as ignorant for having no knowledge of them.
Can you speak two or more languages fluently?
What is the speed of light in a vacuum?
Average distance to the moon in km?
Name all of the amino acids?
Name even half the elements on the periodic table?
Explain why the noble gases rarely combine with other elements?
Why is the moon important?
Conversion formulas for C/F/K or miles/km?
What is a transistor?
Can you fully reinstall Windows and all drivers/applications on your PC or other OS without help?
Can you surf?
My point is simple... It is easy to make fun of others for not knowing something you view as trivial or essential.
We are all ignorant of something.