Given the recent elections, you have to wonder what people know about the U.S. Senate. Okay, I have to wonder because, otherwise, this blog has no real purpose. The Pew Research Center, for example, has asked respondents over the years which party controlled the Senate (see here, Q47). People are relatively stable in their modest knowledge (see below), hovering between 51 and 63 percent correctly identifying the party in control. There does appear to be a slight downward trend from a high of 2003 to today (12 percentage points). That's interesting and suggestive.
For fun (if you can call it fun), I also used ANES data to look at knowledge about the U.S. House before the election. If you eyeball the data you can't spot a linear trend, but if you force feed that data into a logistic regression, with the dependent variable being accuracy at which party controls the House, you do see a modest negative relationship with time (Wald = 8.9, B = -.01, p<.01 for you statistical nerds out there). That's statistically significant but not much of an effect. In the 1960s such knowledge hovered in the mid-60s in terms of percent correct. It bounces up and down, even dropping as low as 28 percent correct in 2002, but was at 72 percent in 2012.
(Nerder analysis -- looking at the interaction of time with other factors, such as education, to see whether the usual relationship between education and political knowledge is greater or less than it used to be. Short answer ... less. It seems, just quickly glancing at some results, the traditional relationship between education and knowledge is less now than it used to be (B = -.02, Wald = 20.7, p<.001). I'd need more time to really get into this).