Do most US Citizens know that Puerto Rico is part of the US?

What percentage of people that live in the U.S. mainland know that Puerto Rico, Virgin Islands, Guam, Northern Mariana Islands, and American Samoa are US Territories, and that the people that live there are United States Citizens? I'm 16 and in High School I was taught that Puerto Rico is another country, and is not part of the US, I was never taught about the Virgin Islands, Northern Mariana Islands, or American Samoa, and I was taught that Guam is another country, and not part of the US. It wasn't until 10th Grade that I learned that Puerto Rico is a territory and my Spanish Teacher taught me that, I had another teacher that year who said it was a country, and not part of the US, and she was a Civics and Economics teacher. I just learned in the past 4-5 months that the US Virgin Islands exist and is a US Territory, and I learned that outside of school. I learned that Guam was a territory a couple days ago, and that The Northern Mariana Islands and American Samoa exist and are US Territories around the same time. I am a honors student and usually get A's and B's with an occasional C. Even the CIA World Fact Book lists them as a country... Why??? I think that at least 60% of the country doesn't know that Puerto Rico is a territory and Puerto Rico's Population is higher than 24 US states, Just under 4,000,000 people live there. Why don't people think it's part of the US? They ARE US Citizens, they can run for president, yet I was wrongly taught that they were Foreign Countries in School, Why? Is this because I live in a majority Republican area? Is it because I live in the Southern US, where you don't have to be smart to become a teacher? Why don't we learn about the US territories in school? My cousin in Canada said that he had to know all the Canadian Prime Ministers, All the Canadian Provinces and Territories, All the US Presidents, and All the US States and Territories in order to p 8th Grade, yet in 10th grade I haven't even been taught all the US Presidents, We briefly went over the US States and Capitals, and haven't been taught the US territories. He lives in another country and knows more about my country than I do, but I haven't had a chance to learn it. Is it like this in the Northern States too?