Jamie Munkatchy teaches juniors and seniors how to make ethanol in their South Bronx classroom.
A trio of girls start shrieking as their crucible of clear liquid catches fire. This is exactly the result they were hoping for.
“It worked!” they scream. “Ms. Munkatchy, we did it!”
The flaming liquid is ethanol, something Jamie Munkatchy’s high school class at Validus Preparatory Academy in the New York City is learning to make this spring. Fermenting and distilling biofuel is not only a lesson in chemistry, but a way to connect their science education to real world problems, Munkatchy said.
“There is a trend in the current educational literature that we should mimic as much as possible or perhaps even just do real science in the classroom,” she said. “Why spend all this time on the background knowledge and who was Bohr and what did his atom look like when there are current science questions going unanswered.”
And the search for alternative fuel sources is one of those key questions, she said. So Munkatchy teaches her students how sugar, yeast and water can become ethanol for their gas tank.
The class makes a mixture of table sugar, baking yeast and water in glass beakers, sealing the tops with rubber balloons. The yeast feeds on the sugar and ferments, creating ethyl alcohol.
But the murky liquid isn’t ready for the gas tank yet. After the yeast has been filtered out of the liquid, the students have to heat the mixture until the alcohol evaporates. Then the vapor has to cool down as it travels through a tube, dripping into a separate beaker as ethanol.
Get the mixture too hot, and the vapor could contain too much water. And if it doesn’t cool down quickly enough, the vapor won’t condense into a liquid, which makes this a very complex task, Munkatchy said.
Then there’s a simple, if a bit dangerous, test to make sure the clear liquid is really ethanol, not water. They have to set it on fire.
The heat from that combustion determines how far a car can go on the fuel — the hotter the flame, the farther the car can travel. Later on the class will measure the heat from burning gasoline, ethanol, and biodiesel to determine which releases more energy.
“I would say I’m trying to develop a pipeline of kids from the Bronx to go into the STEM fields.”
Munkatchy says you can purchase biofuel fermentation and distillation kits, complete with yeast and glassware, but they are expensive. Seventy-five percent of students at Validus Prep in the city’s South Bronx neighborhood qualify for free and reduced lunch, so purchasing these kits isn’t an option. So she has the students make their own distilling devices with glass round bottom flasks, plastic tubing, Bunsen burners and ice.
And the class gets inventive. Some students wrap plastic bags of ice around the tubes coming out of their flasks. Others eschew the ice and opt for cold water. One group created an elaborate path of tubing around the sink’s cold water taps to condense their ethanol. Creative problem solving is a key part of the engineering design cycle, Munkatchy explains, something that will be demanded of them if they pursue a career in the sciences.
“You don’t have to have fancy things to get results,” she said.
When Things Go Wrong in the Lab, Teaching Moments Happen
Originally we planned to include fun, one-minute science experiments on video as part of PBS NewsHour’s STEM teacher series. But even with the best planning, experiments can give you unexpected results, Munkatchy said.
Here’s how our chemistry “magic trick” turned out:
While the experiment didn’t go as planned, it was a teachable moment, Munkatchy said. Once the flames were out, she and I examined my charred twenty dollar bill. One edge wasn’t submerged in the water, she determined, so the flame continued to burn.
When she tried again with another bill, the trick worked.
Chemistry labs are full of potential hazards — corrosive acids and bases, potentially explosive chemical reactions and, most importantly, fire. Safety precautions are crucial, like wearing goggles and keeping fire hazards like long hair, sleeves or headdresses out of the way, Munkatchy tells her classes.
You can’t be afraid of the fire in a chemistry lab, Jamie Munkatchy explained to her students during their lesson on distilling biofuel. Panicking will only make the problem worse, she told them.
Mistakes and accidents happen; you just have to address the problem and learn from the result, Munkatchy said. Usually, the mistakes in an experiment are more valuable than predictable results, she added.
“It is in these moments that I learn the most,” she said in an email. “When students are presented with abnormalities or confusing results they are primed for learning, more so than if experimentation follows a predictable or predetermined outcome. It is exciting, edgy, slightly dangerous – all things I am proud of.”
Do you know a science or math teacher who has a creative lesson plan for his or her students? Send us your nominations here, and your teacher may be featured as a part of this ongoing series.