I was going to say that not even I own an Ontario flag, but that's not true. I do own a set of mini desktop territorial & provincial flags that I had been using to try to teach our 3 year old the provincial flags. I haven't been keeping it up, but ironically, she can only identify the Ontario flag correctly. She also thinks BC is Britain (understandably).
I should go back to teaching her national flags. At one point she kept demanding I open up a map of Europe from Wikipedia will all the flags on it. But, lately we've been teaching her more practical things, like you know... the alphabet.
Yeah, ours are the 4" by 6" flags as well. I agree that national flags are more fun. We mostly focus on the Americas and Asia, because all the places I've taken him are in those parts of the world, but I have gone over some of the European flags as well. Many of the European ones are dreadfully boring, but they're challenging for small children: Can you tell me which is Belgium and which is Germany?
I'll tell you what a great educational tool is: the shower curtain. Right now we have a political map of the world on it, which capital cities marked. It's transparent, but the words and colors are opaque. I also have one with a periodic table of the elements. You can also get them with the flags of the world, subway maps, mathematical puzzles, the solar system planets, bones of the human skeleton, and the Presidents of the United States. Just be sure to install it with the inside out, so that the child can study while he or she showers.