Jennifer Dailey, a doctoral student from the Department of Materials Science and Engineering at the Johns Hopkins University Whiting School of Engineering (right) teaches a class using chocolate. (Photo by Will Kirk/Johns Hopkins University.)

Daniel Friedman needed another science class to complete the requirements toward his degree at Johns Hopkins University. And as a philosophy major, he wasn’t overly confident about diving into a highly technical, rigorous physics or engineering course. Then he saw the word “chocolate.”

“It was an easy sell,” he said.

Friedman didn’t even know what materials science was, really, but he signed up for the winter intersession class. Jennifer Dailey, a doctoral student from the department of materials science and engineering at Hopkins’ Whiting School of Engineering designed the class to test whether students would learn more if they worked with something more familiar and enticing in the lab.

So she taught one materials science lesson on thermodynamics to students in a traditional class. And she compared that to students’ performance in the class learning with chocolate.

Chocolate won.

Okay, maybe “won” is too strong. But based on her data, it was just as effective a teaching method as the metals that are typically used in such classes, and she said the students enjoyed the lesson more.

“It’s an intermediate materials science class on thermodynamics,” Dailey said. “I was teaching concepts from that to students who had very little background — half the students were humanities majors, and they were still able to learn the concepts, which made me very happy.”

Plus, they got to eat tons of chocolate. So much chocolate that in the first class, some students told her it was too much chocolate. (They had recovered in time for the next class.)

Dailey describes materials science as “the study of stuff.”

“There are materials scientists who study metals, how to make them stronger and lighter for airplanes. There are materials scientists who study cells and how to get better drug delivery for cancer treatment,” Dailey said. “There are some that consider themselves effectively chemists, effectively physicists, even electrical engineers. It encompasses a lot of amazing ideas.”

She loves to cook, enjoys the science of food, and seems to have a pretty intense familiarity with local chocolate shops, so the choice of material was easy.

Besides, “there are specific foods that work well for explaining ideas,” Dailey said. “Chocolate has a beautiful crystal structure. It crystallizes in five different ways, depending how you heat and cool it. You can discover how it gets to be a beautiful, shiny candy bar rather than that icky melted thing that you find in your pocket.”

Friedman said the phase diagrams were difficult. And when the students moved on to double phase diagrams, that was daunting. But he was thankful he wasn’t trying to understand it through the structure of lead or iron.

A student pours chocolate during a class session at Johns Hopkins University in the course “Chocolate: An Introduction to Materials Science.” It was offered in January during Johns Hopkins University’s intersession. (Will Kirk/Johns Hopkins University)

Traditionally, to teach a concept such as how to do phase diagrams, you would look at a combination of metals, Dailey said, and ask what phase they will be in at different temperatures and different compositions. “With 60 percent gold and 40 percent copper, what would … ” she said, posing a hypothetical question, and trailed off. “No clue.”

“But if I tell you I take chocolate and vanilla ice cream and heat them up, well, we just made delicious hot chocolate. Cool it down, chocolate milk, or ice cream. Or maybe they will separate — chocolate-chip ice cream. When I gave them that example, it’s very interesting and entertaining to watch the students discovering.”

Grace Scott, a junior double-majoring in international studies and East Asian studies, was drawn to the class by the chocolate, too.

“Ever since I was a kid, I’ve loved cooking and baking and experimenting with different ingredients in the kitchen,” Scott said in an email. “My great-grandfather was an organic chemistry professor and I remember him telling me things like why salt’s chemical compound makes food taste different.”

She was excited when she got off the (very long) wait list, and she enjoyed the lab work, tempering chocolate in various ways, for example, and seeing how it looked like the craggy surface of some far-off planet when magnified 400 to 5,000 times.

“We subjected our chocolate samples to different scientific processes, including the scanning electron microscope, nano-indentation, and X-ray diffraction,” she wrote. “Through these experiments, I was able to better understand chocolate’s molecular structure and its crystallization patterns.”

The class tried to find chemical ways to imitate the smell of chocolate, talked about the ethics of chocolate production, and compared a whole lot of samples to talk about its different characteristics (“Compared” really means more eating of chocolate.)

Johns Hopkins University gave its students the opportunity to take "Chocolate: An Introduction to Materials Science" during intersession this winter. (Johns Hopkins University)

For the final project, they had to explain some concept of science through food and give Dailey an example.

“What would happen if you used baking soda instead of baking powder in cookies?” Dailey said. “Another student, using just chocolate and water and controlled temperature made this gorgeous chocolate mousse. … A student who was a history major made an entire graph of this combination of Nutella with this chemical that made it into a powder.”

And yes, they brought their final projects in. And ate them.

“It was kind of like a big party,” Friedman said. “Having made the chocolate and analyzing it and then getting to eat it — there’s not much better than that.”

Friedman, who’s originally from Budapest, whipped up the caramel milk that people in small villages in Hungary have traditionally enjoyed — chocolate was too expensive for most people back then, he said.


This is a slide from a final project in the Johns Hopkins University course “Chocolate: An Introduction to Materials Science,” explaining the science behind an old Hungarian recipe for caramelized milk. (Courtesy of Daniel Friedman and Victoria Michaels.)

And here, he shares his grandma’s recipe for caramel milk. Because even people who can afford chocolate can — if they study it, think about it, temper it, magnify it, and eat it for three weeks — eventually have enough chocolate.

  1. Pour a cup of sugar into an empty pan on medium heat.
  2. Constantly stir for 3-5 minutes as the sugar starts to brown.
  3. Once sugar is almost entirely browned and mostly liquid, remove from heat.
  4. Stir in 3 to 4 cups of milk.
  5. Enjoy!