HARRISBURG -- It's OK to question the theory of evolution but not to "bash" and "trash" it, an expert witness testified yesterday in a federal trial over the teaching of "intelligent design" in public schools.

The Dover Area School District's curriculum goes too far in discrediting the theory of evolution, testified Brian J. Alters, director of the Evolution Education Research Centre at McGill University in Montreal.

Eleven parents are suing the York County district, claiming the curriculum violates the U.S. Constitution's requirement for separation of church and state.

The ninth-grade biology curriculum calls for teachers to preface lessons about evolution with a four-paragraph statement saying the theory is not factual and mentioning "intelligent design" as alternate theory. The statement tells students that their teacher will not answer questions about intelligent design and refers them to the school library for information about the concept, which says a master designer created the universe.

"This is probably the worst thing I've ever heard of in science education," said Dr. Alters, who holds a doctorate from the University of Southern California. "It's absurd to me that you would bring up a topic and [tell students], 'Go read the book, but don't ask me any questions about it.' I can't imagine anything worse."

Dr. Alters also objected to the curriculum's assertion that the theory of evolution isn't factual.

"That's just dead wrong," he said. "There is no longer debate about it. It is considered factual in the scientific community."

The Dover district is presenting misconceptions while it trashes and bashes a valid scientific theory, he said.

During cross-examination by defense attorney Robert Muise of Thomas More Law Center in Michigan, Dr. Alters acknowledged that all theories, including evolution, are subject to revision as more data is collected.

It's detrimental to students, though, to pit theories of evolution and intelligent design against each other, Dr. Alters said.

Intelligent design is a religious and philosophical idea, not a scientific one, he testified. That's why it doesn't belong in science classrooms, he said.

"You can play the game of science and still have your religious beliefs. They ask and answer separate questions," he said.

The school system, which hasn't yet mounted its defense, is expected to argue that its biology curriculum promotes a fuller understanding of the theory of evolution, including its limitations, and that restricting its curriculum would stifle academic freedom.

The plaintiffs are expected to continue to present their case tomorrow. The defense plans to call its first witness Tuesday.

U.S. District Judge John E. Jones III will apply a two-pronged test.

The first is whether intelligent design and its appearance in the curriculum is religious. Even if he determines the concept is not inherently religious, the plaintiffs can win if the judge finds the school board intended to promote religion in the curriculum.