I'm not sure what the original American electorate could do is that informative. Remember only white male property owners could vote. Those aren't my proposed conditions at all. But I am sure if the founding fathers were born today they would have had the curiosity or education to learn basic algebra.
My beef is not with the media. Why? Because I believe in personal responsibility. It should be a citizen's duty to DEMAND to be informed and have a certain level of knowledge. There are sources out there even including Wikipedia which are more detailed than the garbage the media dispenses. The media is the way it is because that's what numbnuts across the land want.
On the other hand, I don't have a problem with public education providing everyone with what is necessary to pass my fictional citizenship test. Public education allows people to learn algebra and reading today but many people simply fail to take advantage of it.
The point is that those original American voters would probably fail the citizen ship test you are proposing.
The "people" who fail to take advantage of public education are often children. The kids (4th and 5th grade) I tutor in the inner-city are supposed to be learning pre-algebra. I can assure you they've got bigger problems, so how much personal responsibility can you expect from a 9-10 year old? I'm not sure how much personal responsibility you can expect from an 18 year old. Broadly speaking, a person's frontal lobe (where things like logic and reason operate) continue changing rapidly through their early 20s.
You need to consider the idea that you have privileges that allow you opportunities to be more informed than a great many of the people who would fail your "citizenship" test. Many don't have computers or internet access. You could argue that they could go to a library, and they could, but many have more pressing concerns. If you don't own a car a trip to the library could easily consume an entire day.
Frankly I blame the media a great deal. A free press is essential for a healthy democracy, but it isn't a privilege that should be taken so lightly or treated with such a lack of respect.