It seems like every week Americans fail a survey about their knowledge of some important matter, and an expert or politician demands that we require students to study it. In my field, for example, American adults show poor knowledge of the Constitution (many more can name the Simpson family than the five freedoms in the First Amendment). Politicians seize upon such statistics to demand that we “teach the Constitution.”

But we do teach the Constitution. It is included in almost all state standards, and often tested on high-stakes exams. At least 80% of high school students take at least one semester of American Government or Civics, which typically revolves around the Constitution. Nevertheless, in an elaborate study that my colleagues and I conducted, we found that (a) studying the Constitution made only a modest impact on students’ ability to answer survey questions about the Constitution; and (b) state requirements made absolutely no difference in what students knew. Even if state requirements did boost students’ knowledge, it would be an open question whether such knowledge lasts.

Besides, we could play this game all day–citing important survey questions that Americans fail to answer correctly, and demanding that these subjects be mandated in our schools. For example:

1. According to the the National Environmental Education and Training Foundation, “45 million Americans think the ocean is a source of fresh water; 120 million think spray cans still have chlorofluorocarbons (CFCs) in them even though CFCs were banned in 1978; another 120 million people think disposable diapers are the leading problem with landfills when they actually represent about one percent of the problem; and 130 million believe that hydropower is America’s top energy source, when it accounts for just ten percent of the total.” Sounds like an argument for mandatory environmental education–which I would support in principle, but many states already have such mandates.

2. A plurality of Americans believe that “God created man pretty much in his present form at one time within the last 10,000 years,” even though almost every student has to study evolutionary biology.

3. According to the Kaiser Family Foundation, “In 2006, more than one-third of the public (37%) thinks HIV might be transmitted through kissing, 22% think it might be transmitted through sharing a drinking glass, and one in six (16%) think it might be transmitted through touching a toilet seat. More than four in ten adults (43%) hold at least one of these misconceptions.”

Before we jump to the conclusion that a curricular mandate would solve any of these problems, we need to ask: 1) Does a snap telephone survey of factual questions yield valid information? (Maybe people would do a lot better if they had a chance to prepare.) 2) Is educating kids the best way to reduce ignorance among adults? (That implies that factual information imparted in high school lasts for decades.) and 3) Do educational mandates cause good outcomes in classrooms? (I doubt it.)

The alternative is to work on improving the actual impact of instruction on important topics.