I have absolutely no idea where that conclusion comes from. People feel qualified to proclaim opinions, because it jibes with that thing they heard on TV that one time. And yes, I am aware of the irony in the context of my original post, but I am just citing the most recent incident in a long history of such things which I feel represents the current popular mindset.

Just as an anecdotal example, I had my American history class in high school attempt to read selections from the Federalist Papers, and it was like banging my head against a wall. Those papers themselves, written to persuade the general electorate of the efficacy of the constitution, cited a broad range of historical examples and precedents that would have many contemporary graduate students scrambling for references. The expectations at the time on what constituted general knowledge were simply higher. I had, by the time we got around to American history, a sufficiently low opinion of my students that I considered it par for the course that they could not identify all 50 states of the US on a blank map, or list the Presidents in order (just in order, not even asking them to list their years in office or parties or VPs or anything like that - merely to get the sequence correct). It was much more surprising that everyone ELSE believed I was expecting a bit much from high school SENIORS, as well as Freshmen (some subjects, like the humanities, which didn't depend on prior knowledge, were rotated so the whole school took them in the same year, to save on books & teachers and whatnot), or that most people CANNOT name those things offhand. I thought the "Friends" episode, where they spent all of a Thanksgiving gathering driving themselves nuts trying to list all the states was the usual later-season stupidifying of the characters, until my sister proposed a similar game during one vacation, claiming it always stumped everyone at parties. My elementary school expected third graders to remember the presidents in order. My father, when working as a municipal zoning officer, used the phrase "Cross the Rubicon" at work, and was met by incomprehension from his coworkers. He asked around the Town Hall, and found that NOT ONE PERSON involved in the municipal government of a prosperous suburban industrial/commercial town, knew either the general meaning nor the origin of the phrase. In our education system, that was 3rd to 5th grade knowledge. I definitely recall learning it before I was ten, but I was a history buff even back then, relatively speaking. It was still in the set of books that we used for grammar school.

When I took geometry in my sophomore year of high school, I paid little attention when we came to circles, because I was bored, having learned it all already in 5th grade. I was among the last students to finish the test on that section, and I got back an abysmally low grade. When I spoke with the teach about it, it turned out I got every problem right, but because I solved for Pi, like I had done in 5th grade, the teacher had no idea what my answers were. In other words, when they asked for the area of a circle with a diameter of 4, the teacher was looking for 4pi, while I gave 12.57 (i.e. 4 x 3.1416). My 5th grade teacher expected more math work than did my 10th grade teacher. This was at Don Bosco Prep, which for all that its current national reputation is about football, was primarily academic, and intensely focused on getting its students into college.

You would be right in your suspicions, seeing as how Obama himself has been quoted as mentioning "all 57 states". Also, I strongly suspect that poll is bullshit. I'd really like to see what the actual question asked was, that was reported as "thinks he's a Muslim."