In a Central High School science lab - with her teacher and 30 classmates huddled around - freshman Mjaan McIvor pointed a camping lighter toward a single marshmallow Peep.

The jack-o'-lantern-shaped Peep was sitting on top of an inch-tall stand and inside a six-inch metal cylinder with a beaker of water placed above it.

After some difficulty igniting the lighter, McIvor succeeded in setting the Peep on fire.

It was a visual, personal, hands-on science experiment - the kind of interactive approach that teacher K.D. Davenport believes will leave her students with a deeper understanding of nutrition.

In this experiment, the freshman biology class was trying to determine how many calories were in the Peep. The metal cylinder was a calorimeter, and the change in temperature of the water after McIvor set the Peep on fire was the basis for the class' calculation.

"It's fun," said McIvor, as she attempted to calculate how much energy she had just burned from the Peep. "At first I was mad because I couldn't [light] it."

McIvor's classmates in the third-period biology class were also finding Davenport's curriculum engaging.

"At my old school we would just read a book," said Chris Warenecki, referring to a previous health class. "Now I'm more interested. It's a lot more fun."

Davenport, in her second year teaching science full time at Central, two years ago was awarded a five-year fellowship from the Knowles Science Teaching Foundation, which awards fellowships to high school math and science teachers. She credits Knowles with aiding her development as a teacher, especially giving her the encouragement to try new ways of bringing interactivity to her classes.

"Two years ago I wouldn't have done this," Davenport said. "I would've been too scared to try. My teaching was more lecture-based."

But Knowles asks its fellows to take more initiative to develop innovative teaching methods. Then it funds their ideas.

The materials used for Davenport's nutrition lab - including four calorimeters, a few scales, and molecular model kits - cost Knowles $600.

Davenport worked with two other high school science teachers, one from San Francisco and one from Upstate New York, to develop these nutrition exercises.

Next year, she hopes to be able to show her classes how to calculate the calories in an entire meal from the school's cafeteria.

With each new idea for implementing her curriculum, Davenport has become more skilled at teaching by showing rather than telling.

"I used to be a little disorganized with lab projects," Davenport said. "The uncertainty made me uncomfortable."

Take the Peep-burning experiment. For reasons beyond the students' control, their answer showed that the Peep contained one calorie, when in fact it has about 25.

"That's something that would have rattled me in the past," said Davenport, who wasn't sure where the experiment went awry. "But learning to deal with inaccuracy is a part of science." And, she added, the class could still benefit by trying to quantify the variables.

"Students tend to want to be perfect or don't try at all," said Davenport, saying that she hopes she imparts to them that there can be a middle ground. "I hope my students notice that I'm open to new things and I'm not stupid for making mistakes."

Her students have taken to her more hands-on, visual approach.

"It's easier to follow," ninth grader Alison Liu said. "It's a lot more interesting than just reading about it."

Classmate Nicholas Marshall agreed. "It's interesting to actually see what's happening," he said.

For at least one student, fully understanding the meaning of calories had another result.

Davenport's class has inspired McIvor to watch what she eats.

"I didn't eat healthy at all," she said. "Now I do."

Contact staff writer Luke Harold at 215-854-5626 or