An essay by Michael Berkman and colleagues in the current PLoS Biology reviews the results of the National Survey of High School Biology Teachers as relevant to evolution and creationism. The study has gotten some press, for example this New Scientist article:
The researchers polled a random sample of nearly 2000 high-school science teachers across the US in 2007. Of the 939 who responded, 2% said they did not cover evolution at all, with the majority spending between 3 and 10 classroom hours on the subject.
However, a quarter of the teachers also reported spending at least some time teaching about creationism or intelligent design. Of these, 48% -- about 12.5% of the total survey -- said they taught it as a "valid, scientific alternative to Darwinian explanations for the origin of species".
The first paragraph of the essay's conclusion summarizes the reason for concern.
Our survey of biology teachers is the first nationally representative, scientific sample survey to examine evolution and creationism in the classroom. Three different survey questions all suggest that between 12% and 16% of the nation's biology teachers are creationist in orientation. Roughly one sixth of all teachers professed a "young earth" personal belief, and about one in eight reported that they teach creationism or intelligent design in a positive light. The number of hours devoted to these alternative theories is typically low -- but this nevertheless must surely convey to students that these theories should be accorded respect as scientific perspectives.
It does seem surprising to me that a sixth of biology teachers would express views consistent with young earth creationism -- I mean, what drew them to biology? But I don't think that the proportion by itself is alarming. I mean, it's a lower percentage than the general public. And I'm not persuaded by the idea that students will have "positive role models" for developing the idea that creationism is a scientific theory. They have plenty of positive role models already.
What really does concern me is the absolute minimal amount of time that high school biology courses spend on evolution. Without evolution, biology really lacks any mechanism to talk about cause and variation -- dissecting a fetal pig may help show you how the body works, but it can't show you why different individuals should vary, or why drugs should have different reactions in different people, why genetic disorders shouldn't happen very often, but why they sometimes happen anyway, why hybrid corn works but hybrid dairy cattle don't, and why oil just broke $130 a barrel and is still rising. In other words, important stuff -- the sort of basic consumer knowledge of biology that we want future citizens to know.
Here's what the study revealed about time spent on evolution:
We followed most previous studies in asking teachers to think about how they allocate time over the course of the school year. We went a step further in also asking whether evolution serves as a unifying theme for the content of the course. Over the entire year of high school biology we found substantial variation among America's high school teachers (see Table 1). Not surprisingly, we found that those who take most seriously the advice of NSES to make evolution a unifying theme spent the most time on evolution. Overall, teachers devoted an average of 13.7 hours to general evolutionary processes (including human evolution), with 59% allocating between three and 15 hours of class time (see Table S1). Only 2% excluded evolution entirely. But significantly fewer teachers covered human evolution, which is not included as an NSES benchmark. Of teachers surveyed, 17% did not cover human evolution at all in their biology class, while a majority of teachers (60%) spent between one and five hours of class time on it.
That's two and a half weeks of classroom time on evolution, out of a year-long course in biology.
What actually scares me is the number of practicing biologists -- especially geneticists -- who are working only on the knowledge of evolution they got in high school biology. Because university genetics, biochemistry, and biology curricula often require no coursework in evolutionary biology. They need no coursework at all in human evolution. So you wonder how they get to be practicing researchers while knowing nothing at all about the number of people who built the pyramids. Here it is. And high school biology teachers may have only a smattering of evolution in their collegiate biology training. It's no mistake that many teachers don't see it as a central issue -- neither training programs nor state standards tend to require any substantial knowledge about evolution.
Some teachers have a much better idea -- make evolution a central theme, and spend nearly four weeks on it. These are balanced by others who think that no evolution at all is necessary:
Those teachers who stressed evolution by making it the unifying theme of their course spent more time on it. Overall, only 23% strongly agreed that evolution served as the unifying theme for their biology or life sciences courses (Table S2); these teachers devoted 18.5 hours to evolution, 50% more class time than other teachers. When we asked whether an excellent biology course could exist without mentioning Darwin or evolutionary theory at all, 13% of teachers agreed or strongly agreed that such a course could exist.
This is a deep division, which also exists at the university level. There are a large group of "science-friendly" people who do not understand evolutionary biology, and who do not have a practical idea of its importance. These people are without a doubt against teaching creationism in science courses, but they cannot be for evolution except in the most nebulous sense, because they have no more than a nebulous idea of what evolution is. Unfortunately, some professional biologists, geneticists, and other scientists are among this group.
We're entering an age in which health decisions will be made based on genetic information -- when everyone may know their own gene sequences if they want to. New diseases are emerging, new crops are being developed, and new organisms are being transplanted from one continent to another. Decisions about the economic development of entire regions -- perhaps entire nations -- are now subject to the evaluation of biodiversity, including threatened and endangered species.
The people making these decisions ten to twenty years from now will have an average of 13.7 hours of education on evolution.
Berkman MB, Pacheco JS, Plutzer E. 2008. Evolution and Creationism in America's Classrooms: A National Portrait. PLoS Biol 6(5): e124 doi:10.1371/journal.pbio.0060124