Maybe that's the level you feel comfortable with? That's great until someone smarter than you comes along and thinks that the test is too easy and too many "uneducated" people are voting. I love history and politics, but I don't know everything and I know that there are tests that can be drafted that I can't pass. Are you willing to be on the outside looking in, willing to be presented with a test so hard you can't pass it and can't vote? Willing to be represented by officials that you can never peacefully vote out of office? How long until a narcissist decides that they're the only one smart enough to vote? That's unfortunately the fate of every country that's fallen into a dictatorship.
I see that you want an educated electorate but voting tests have been tried before and tons of innocent, smart, well-intentioned people get cut off in the process. Democracy is the only form of government we know of where we can meaningfully and non-violently express our collective opinion as a group. When you take a vote away from someone, they're left with a choice between compliance or violence, neither of which are good.
Maybe, the paid public education you mention would still be a good idea, just without the voting rights test.
The problem is what grade level?
1st grade: What country do you live in?
3rd grade: Name all 3 branches of government
6th grade: How is a bill made into a law?
9th grade: Who are your elected representatives and what are their positions on issues A, B & C?
...
PhD: Compare and contrast Hamilton and Jefferson's viewpoints on the Constitutional convention, banking and personal liberties and how they shaped and influenced US policy in the last 40 years (20 pages or less)
Countries have tried an aristocratic, ruling class and it doesn't work because it disenfranchises the masses and leads to a populist revolt.
These tests were also used in the US to disenfranchise minorities who couldn't read or afford to go to school.
Plus, I had a friend in college who was one of the 537 deciding votes in Broward county in 2000 who voted for Bush because "Gore was boring". He was smart and would have easily passed any civics test you gave him, but he voted based on personality rather than any specific issue.