Teaching students to be 'competent jurors' on evolution

I am a public high school biology teacher, and I do an unusual thing. I teach my students more than they have to know about evolution. I push them to behave like competent jurors - not just to swallow what some authority figure tells them to believe - not even me - but rather to critically analyze, with an open mind, the evidence set before them.

Scientific theories have come and gone for centuries, replaced by better ones as new evidence arises. There has always been controversy in science and tremendous opposition to those who challenge the orthodoxy of the day. An effective way to teach science is to explore some of these controversies.

Teenagers, not surprisingly, find this approach exhilarating.

When I note that contrary to their large and monolithic biology textbook, some highly credentialed scientists insist that there are limitations to Darwin's theory, the students perk up.

And when I note that some current biology textbooks contain widely discredited evidence for Neo-Darwinism - a synthesis of Darwin's theory of evolution and Gregor Mendel's theory of genetics - the last of the sleepy looks in the classroom usually vanishes.

Skepticism for its own sake isn't the goal here, but it's important for students to realize that even respected scientists have peddled fraudulent evidence in defense of a pet scientific dogma. A few examples my students learn about are Ernst Haeckel's faked embryo drawingsand the infamous Piltdown Man - fossils of a primitive hominid that turned out to be a hoax.

I also expose students to the reputable evidence for evolution. They learn about some of the pillars of evolutionary theory - genetically altered fruit flies, the evolution of antibiotic resistance in bacteria and insecticide resistance in bugs, how breeding programs change domestic species, and how oscillating climates affect the beak size of certain kinds of finches. These and other examples demonstrate that organisms are capable of change over time.

What is the significance, I ask my students, of these microevolutionary changes? Can they be extrapolated to explain macroevolution - that is, evolution from one type of creature to a fundamentally different kind?

I also dissect these evidences using recent discoveries that have raised important questions among evolutionary biologists.

My students learn that even highly trained biologists disagree on these issues, interpreting "hard" evidence in different ways.

The job of the scientist, I explain, is to find the best explanation to a problem, not just to defend his or her own position at all costs.

After my presentations, many kids will ask what I believe, since they cannot tell what my position is.

One such student told me she appreciated my neutral approach. Her reason was simple: hearing the evidence for and against the theory gave her the freedom to weigh the evidences for herself.

This student eventually wrote an article for our local paper about my approach. After it was published, a reporter from that paper appeared unannounced, interviewed me, and called my superintendent to ask if she knew how I was teaching evolution.

My principal saw that it was a freedom of speech issue and gave me his full backing.

My superintendent asked me to stick to the adopted curriculum - which does not include intelligent design theory - and I've done so. However, I have retained the freedom to mention intelligent design theory to curious students as another viewpoint used to explain life and its diversity.

The superintendent reminded me to remain neutral in my presentation, and gave me her backing.

We were on firm legal footing. Constitutional law allows this approach:

The Supreme Court has ruled that it is permissible to teach students about alternative scientific viewpoints and scientific criticism of prevailing theories.

And a June 2001Senate addendum to The No Child Left Behind Act states, "Where topics are taught that may generate controversy (such as biological evolution), the curriculum should help students to understand the full range of views that exist ...."

Finally, this approach comports with the state of Washington's high school assessment test, which expects students to be able to think critically, analyze information, and draw informed, reasoned conclusions.

Charles Darwin wrote, "A fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question."

That, in my opinion, is what science is all about.

• Doug Cowan is a veteran science teacher at Curtis Senior High School in University Place, Wash., where he teaches biology, physiology, and human anatomy.