Each year, dozens of states have bills introduced that target science education, mostly focused on the teaching of biology. Working off a template provided by a pro-intelligent design think tank, the bills would encourage the use of nonstandard teaching materials or targeted criticism of evolution; in some cases, they throw in climate change and the origin of life. In most states, they never make it out of committee, but Tennessee has made an exception this year, as the state's House passed a bill by a wide margin.

So far, the only state to enact a law that targeted "evolution, the origins of life, global warming, and human cloning" has been Louisiana. For the last two years, schools in that state have been able to approve supplemental materials that cover these topics, giving local authorities the legal (but not necessarily the intellectual) ability to decide what might constitute valid scientific criticisms.

The Tennessee bill is somewhat different; rather than seeking to introduce new material into the classrooms, it effectively removes the ability of administrators to determine how a subject is taught. No school authority in the state "shall prohibit any teacher in a public school system of this state from helping students understand, analyze, critique, and review in an objective manner the scientific strengths and scientific weaknesses of existing scientific theories covered in the course being taught." Even though it's supposedly about science education, there's an entire clause (one of only five) devoted to saying the whole thing has nothing to do with religion.

Tactically, that is probably a good decision for the creationists who are pushing for the bill. Supplemental materials are open to objective analysis of their scientific merit, which might go badly in court; verbal classroom instruction can be much harder to parse, and might come down to the words of students against those of their teacher. The shift may also be inspired by recent events in nearby Ohio, where a teacher was fired for conduct that included distributing creationist material to his science classes.

The state Senate is currently considering a similar bill. The National Center for Science Education is tracking the events there and in other states.