Kevin A. Lavigne awoke at 4 a.m., afraid that his chemistry students would ruin the experiment that had incubated for a month in his closet.
What if, he thought in the predawn hours of Nov. 9, they add too much hydrochloric acid at one time? If they don’t do it right the first time, they’ll lose the chance to collect data that will help them understand how much life—although microscopic—exists in Antarctic soil.
The answer, he decided, was to let the students become familiar with the lab equipment and the chemical reactions they would be creating with it by working with a chemical solution that didn’t matter.
“In science, you practice before you try it,” he tells his 11 o’clock class that morning. “Today, we’ll have a dry run.”
“Phew,” a student in the front row sighs.
Teacher Kevin A. Lavigne and a sample of the Antarctic soil that his students are testing. —Allison Shelley |
Mr. Lavigne, one of seven teachers selected to accompany a team of scientists to Antarctica this winter, is scheduled to depart this college town across the Connecticut River from Vermont on Jan. 2 and be gone for eight weeks. In the months leading up to his departure, he searched for ways to introduce his students at Hanover High School to the research he’ll conduct on his adventure.
“I like to see the kids do open- ended experiments,” said the 33-year-old, who has taught at the high school for four years. “They should be able to solve problems, or at least set up a procedure to solve them.”
And Mr. Lavigne also found ways to tie his students’ learning to his upcoming journey.
While he’s in Antarctica, he will conduct experiments created for him by Hanover High physics students, comparing the data with what they collect in New England. This spring, his evolution classes will analyze the DNA of nematodes, the microscopic worms that make up most of the life in the few sections of the frigid continent that are covered with soil.
Earlier this fall, Mr. Lavigne’s chemistry classes analyzed soils the same way he will in Antarctica with the accompanying research team of scientists from nearby Dartmouth College and from Colorado State University.
More Than Dirt
In October, Mr. Lavigne’s students sealed soil in Mason jars, with a small vial of sodium hydroxide in each jar. The vial collected the carbon dioxide produced by the dirt’s microbes released over the next month. The soil included three samples from Antarctica’s Dry Valleys, a local organic farm, and a U.S. desert grassland. Some jars were empty to provide a control that demonstrated how much carbon dioxide is generated in the air.
By determining how much carbon dioxide the three soil samples emit, students compared how much microbial activity was occurring in each.
“I’m running the exact same experiment,” said John Barrett, a postdoctoral fellow at Dartmouth who will travel to Antarctica with Mr. Lavigne. And like the Hanover High students, Mr. Barrett conducts a “dry run” before he works with incubating soil.
When the jars are unsealed the day after the dry run, the students add barium chloride to the contents of the vial. At that point, they conduct a titration, a common chemistry method in which hydrochloric acid is added to the solution collected in the soil samples. The alkaline, or pH, levels of the solution start out high as the class begins adding acid, and it stays that way for the first few milliliters. Then, the pH level falls suddenly with every extra drop of acid. It eventually levels off near zero.
If students add too much acid too quickly, they will miss that sudden drop and won’t be able to calculate the “equivalence point,” the key piece of data that lets them calculate the amount of carbon in the soil.
During the Nov. 9 dry run, most students start cautiously, adding one drop at a time. Despite Mr. Lavigne’s urging to be patient, most express frustration because the pH levels in their solutions don’t change after they add a couple milliliters of acid.
But once they start to see the pH level drop precipitously, they respond just as their teacher hopes, putting in one drop of acid at a time.
“Yeah, one drop makes a big difference,” one youth says to his lab partners, who are registering the data on their graphing calculator.
On Nov. 10, just about every lab team finds the results the teacher is looking for.
Even though the lab grew out of preparations for his Antarctic trip, Mr. Lavigne says he may use the experiment again. If he doesn’t have any Antarctic soil next year, his students can always compare the carbon levels on local soils. “There’s a lot of good chemistry in that lab,” he says.
And what’s equally important, he adds, is that students had the opportunity to see that scientific experiments require practice, diligence, and patience. It’s a lesson they don’t learn when the teacher outlines what the students should do and tells them the results they should expect, much like following a recipe.
“We do students a disservice if they have 11 years of science and all they know is how to do ‘cookbook’ labs,” Mr. Lavigne says.
Fun With Physics
On the afternoon of Friday, Nov. 10—after the chemistry labs are complete—Mr. Lavigne spends his preparation period watching physics students taught by Carl Mehrbach design experiments for him to conduct in Antarctica. Their assignment is to create an experiment that will compare how heat transfers in the polar region with how the process works in New England.
One team assembles four pieces of cardboard that look like a topless box and places a light bulb in the center. Each cardboard piece is wrapped in aluminum foil and has a different color of construction paper facing the light. The goal is to see which color collects heat the fastest.
As the team finishes building its apparatus, the period is about to end. But the boys in the group quickly run a test to see if their device works. They attach thermometers to the aluminum foil and connect them to the computer. They turn the light on and watch the heat slowly raise the temperature of the foil at a different rate on each side of their contraption.
“This is my first experiment in all of high school that actually worked,” shouts Jeff Christiansen as his lab partners head out the door to their next class.
Mr. Christiansen and his partners will return the following Monday to collect data and learn which color collects heat the fastest. For now, they’re happy to have a device that works in Hanover, N.H.
The results in New England may be significantly different from those in Antarctica, physics teacher Mr. Mehrbach says. The lack of ozone, the lower temperatures, and the different angle of the sun in Antarctica all may contribute to a different mode of heat transferrence, he hypothesizes.
A physicist with whom Mr. Mehrbach has consulted says that scientists know very little about heat transfer near the South Pole. What’s more, that same physicist holds out an exciting prospect: Mr. Mehrback’s high school students just might collect data that could lead to a published paper in a professional journal.
