- The Washington Times - Wednesday, September 28, 2005

Washington-Lee High School’s Stacy Brasfield asks her students the second day of each school year to stare at a candle.

Ms. Brasfield, a 10th-grade chemistry teacher at the Arlington school, says that basic act is the first step toward thinking like a scientist.

“It sounds simple, but then we talk about. They make observations before it’s lit, after it’s lit,” says Ms. Brasfield, adding the process leads students toward the tenets of the scientific method, which compels researchers to observe, hypothesize and then test various theories.

Why does the wick burn and the wax melt? What chemicals are given off when the candle burns?

It’s all part of a good classroom experiment, the kind that keeps students’ attention while teaching them important lessons about the world around them.

A worthwhile experiment could be anything from a faux volcano complete with chemical eruptions to the tried-and-true frog dissection.

What unifies such a setup is both the experiments’ ability to amaze, plus the lessons they impart.

Students don’t always take the scientific bait.

“Sometimes I have to nudge it out of them with a class discussion,” Ms. Brasfield says. “I’m not really answering their questions. I’m just asking them more questions.”

Barbara Dietsch, a science teacher at Cabin John Middle School in Potomac, says it all begins with safety. Each year, Ms. Dietsch gives her students a contract they and their parents must sign about how to conduct experiments in a safe manner.

“They have to have 100 percent test scores on safety tests before they go into the laboratory,” Ms. Dietsch says.

From there, it’s often a trip to the Chesapeake Bay. Montgomery County sixth-graders take a three-day trip to various sites along the Bay to conduct experiments in a true environmental setting. They test variables relating to water runoff — does that runoff go faster over gravel or asphalt surfaces among their findings.

Digestion exercises prove a perennial favorite, she says.

One experiment lets students test for carbon dioxide by dipping a cow’s liver in hydrogen peroxide and watching as gas bubbles are released.

The scientific highlight for many seventh-graders remains the frog dissection unit.

“They dissect in a group. Some students just watch. Other kids love to be the surgeons,” she says.

The lesson reinforces the teachings regarding digestion in a way the textbooks can’t match.

“It’s still quite valuable. We talk about the stomach, but now you can feel it,” says Ms. Dietsch, adding students who for whatever reason prefer not to participate can follow along with a complementary, and less squishy, lesson plan.

Steve Long, high school division director for the National Science Teachers Association in Arlington, says not all experiments endure. The classic classroom volcano, a bubbling mound fired by ammonium dichromate, has gone the way of the dinosaur, he says.

“It could be uncontrollable. The sparks might fly and cause some problems,” says Mr. Long, who works as a chemistry teacher at Rogers High School in Rogers, Ark. “It produces some things that are toxic and possibly carcinogenic.”

Other experiments still have their functions.

“I still use many of the same science experiments I used 31 years ago,” he says. “They’re solid science, they work well and they’re very reliable. But you continue to try to find things more effective. That may mean flashier or cheaper or something that’s completely different.”

Sometimes, science teachers take for granted what they know and students have yet to process.

Mr. Long often gives students samples of various elements to examine at their desks.

“They look at them, examine the color and hardness … for teachers we’ve done this but we forget they often don’t have that exposure.”

Students love any experiment that lets them use their senses, he says, especially experiments involving heat or light.

“They like things that have vivid color changes or things that don’t proceed the way you think they would,” he says.

A good example of that is mixing two colorless solutions and watching the brew turn bluish-black. The solutions — one a starch, the other an iodine compound — react vigorously after a few seconds of exposure.

“It’s so unexpected and instantaneous,” he says.

Constance Skelton, a science supervisor with the Arlington School District, says most science teachers try tying their lessons into factors every student can understand.

“They’re trying to make some real-life connections,” Ms. Skelton says, adding the better experiments are open-ended to let students make their own hypothesis.

Toward that end, the district’s seventh-graders might grow yeast in a variety of settings to learn how those cells blossom, then devise ways to speed up the yeast’s activity on a cellular basis. Often, the experiments are conducted like a home economics class, with students watching homemade bread rise at various levels.

Other students study how to protect Arlington buildings from acid rain.

The best experiments often click with students for their sheer spectacle. After all, what could be more fun than watching a needle pierce a balloon that refuses to break?

“If it has some kind of ‘wow’ effect, something the students don’t expect to happen, you have them hooked,” says Ms. Skelton, explaining how the balloon’s polymer structure can withstand the steady pressure of the sharp needle if handled just right.


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