Paleontologist Marcus Ross speaks under a towering tyrannosaurus rex at the National Museum of Natural History in Washington to students from Liberty University’s Advanced Creation Studies class. Each year the class travels from Lynchburg, Va., to visit the museum which, like all mainstream natural history institutions, is fundamentally Darwinian.

Washington ? Every winter, David DeWitt takes his biology class to the Smithsonian’s National Museum of Natural History, but for a purpose far different from that of other professors.

DeWitt brings his Advanced Creation Studies class up from Liberty University in Lynchburg, Va., hoping to strengthen his students’ belief in a biblical view of natural history, even in the lion’s den of evolution.

His yearly visit is part of a wider movement by creationists to confront Darwinism in some of its most redoubtable secular strongholds. As scientists celebrate the 200th anniversary of Charles Darwin’s birth, his doubters are taking themselves on Genesis-based tours of natural history museums, aquariums, geologic sites and even dinosaur parks.

“There’s nothing balanced here. It’s completely, 100 percent evolution-based,” said DeWitt, a biology professor. “We come every year, because I don’t hold anything back from the students.”

Creationists, who take their view of natural history straight from the book of Genesis, believe that scientific data can be interpreted to support their idea that God made the first human, Adam, in an essentially modern form 6,000 to 10,000 years ago.

A 2006 poll by the Pew Forum on Religion & Public Life found that 42 percent of Americans believe humans have always existed in their present form. At universities such as Liberty, founded by the late Jerry Falwell, those views inform the entire science curriculum.

Like the Liberty students, avowed creationists nationwide are challenging the conventional wisdom at zoos (questioning the evolutionary explanation of giraffe necks), the Grand Canyon (dating the rock layers in thousands, not millions, of years), and cave parks (describing the formations as evidence of rapid drainage after the Great Flood).

In the upcoming issue of Answers, a leading magazine of the young-Earth movement, the list of “creation vacations” includes the Lowell Observatory in Arizona, the New England Aquarium in Boston and London’s Natural History Museum.

“Why should we be afraid to test our worldview against reality?” asked Bill Jack, a Christian leadership instructor at a company called Biblically Correct Tours. “If Christianity is true, it better be true in the natural history museums and in the zoos.”

Creationists have been popping up in enough mainstream institutions that one museum has produced a creation-vs.-evolution primer to help volunteer docents handle their questions. When the Museum of the Earth in Ithaca, N.Y., published its guide, more than 50 museums called looking for a copy, according to director Warren Allmon.

But creationists say the purpose of their visits to what some describe as “temples to evolution” is to train themselves to think critically, not to pick rhetorical fights with curators or other visitors.

“I’m not standing up and saying to everybody in the room, ‘Gather around,’ ” Jack said. “That would be disruptive. But I’m speaking loudly enough for my people to hear and sometimes others join in.”

Smithsonian officials said they were unaware of any organized visits by avowed creationists but said they are welcome. Still, all visitors should know that the museum — like all mainstream natural history institutions — is fundamentally Darwinian, said spokesman Randall Kremer.

“Evolution is the unifying principle for all the biology, past and present, in our halls,” Kremer said. “That is the foundation of the research we conduct at the museum.”

Actually, the Liberty field trippers didn’t find much to object to at their first stop, the museum’s soaring hall of fossils. DeWitt’s main complaint was that the 1980s-era introductory film on the beginning of life was woefully outdated (lots of dancing amoebas, no mention of DNA).

“It’s embarrassing,” said DeWitt, who found himself filling in some of the latest evolutionary thinking for his students. His Ph.D. in neuroscience is from Case Western Reserve University. “As an educator, I want them to see the most up-to-date material.”

The 20 students listened attentively as co-leader Marcus Ross, an enthusiastic paleontologist who teaches at Liberty, expertly explained about the world-class fossil collection and told ripping tales of the towering tyrannosaurus rex that was casting skeletal shadows over the group.

“I love it here,” said Ross, who has a doctorate in geosciences from the University of Rhode Island. “There’s something romantic about seeing the real thing.”

Modern creationists don’t deny the existence of dinosaurs but believe that God made them, and all animals, on the same sixth day that he created man. In fact, Ross’s only real beef in the fossil hall is with the 30-foot lighted column that is a timeline marking 630 million years of geology. As a young-Earth creationist, he asserts that the vast majority of the rocks and fossils were formed during Noah’s flood about 4,000 years ago. Most paleontologists date the T-Rex to 65 million years ago.