American adults in general do not understand what molecules are (other than that they are really small). Fewer than a third can identify DNA as a key to heredity. Only about 10 percent know what radiation is. One adult American in five thinks the Sun revolves around the Earth, an idea science had abandoned by the 17th century.
Interestingly, Miller himself locates the failure as starting all the way back with our public school systems, which he says are underfunded: "This country cannot finance good school systems on property taxes". I personally would push this argument further and wonder what the "uneven geography" of scientific literacy in the US looks like. Which school systems produce the most scientifically illiterate students (either in numbers of students falling below a threshold of understanding, or lowest overall misunderstanding for a comparable population of students). But I too suspect that with more resources devoted to teaching students about the natural, material, physical, and human-built world and the science, natural history, mathematics, and engineering which underlie it, scientific literacy could be greatly improved.
It seems like there are more dots to be connected, however. We may be living in an "information economy" as measured by our production, consmption, and productive use of information-processing devices and information-rich media, but if we are to claim that we live in a "knowledge society" then we need a different set of measures. A society with twenty-first century technology should be appalled to find out that any significant percentage of its children live comfortably with "common sense" ideas that were discredited in the seventeenth century.