DALLAS  Opponents of teaching evolution, in a natural selection of sorts, have gradually shed those strategies that have not survived the courts. Over the last decade, creationism has given rise to “creation science,” which became “intelligent design,” which in 2005 was banned from the public school curriculum in Pennsylvania by a federal judge.

Now a battle looms in Texas over science textbooks that teach evolution, and the wrestle for control seizes on three words. None of them are “creationism” or “intelligent design” or even “creator.”

The words are “strengths and weaknesses.”

Starting this summer, the state education board will determine the curriculum for the next decade and decide whether the “strengths and weaknesses” of evolution should be taught. The benign-sounding phrase, some argue, is a reasonable effort at balance. But critics say it is a new strategy taking shape across the nation to undermine the teaching of evolution, a way for students to hear religious objections under the heading of scientific discourse.

Already, legislators in a half-dozen states  Alabama, Florida, Louisiana, Michigan, Missouri and South Carolina  have tried to require that classrooms be open to “views about the scientific strengths and weaknesses of Darwinian theory,” according to a petition from the Discovery Institute, the Seattle-based strategic center of the intelligent design movement.