Behind the scenes, Brown’s physics demonstration manager makes an impact on student learning

Responsible for organizing demonstrations designed to illustrate complex concepts in physics, Angella Johnson plays an essential role in enhancing students’ academic experiences.

PROVIDENCE, R.I. [Brown University] — The nearly 40 students in Jia Li's class at Brown University leaned in as he approached the climax of his lesson on artificial gravity.

Li, an assistant professor of physics, held a few pieces of pink string in one hand. Dangling from the string was a silver tray with a water-filled wine glass on it. Li started to swing the tray like a pendulum, assuring students he’d be able to swing it over his head without spilling a single drop. “It will be as if there’s this imaginary hand holding it all,” he said of the experiment known as the Greek waiter’s tray.

A few students looked away as Li let it rip, bringing the tray over his head in a blur of dizzying swirls. Nothing spilled. Nothing shattered. And after Li returned the tray to a slow pendulum-like swing, the class broke out with a round of applause.

“I’ll admit, I was bit nervous,” Li told them, smiling, before he launched back into the bulk of his lecture.

Unseen in the classroom — but integral to the success of this experiment — was Angella Johnson, demonstration manager for Brown’s Department of Physics.

“When faculty in the department want to show certain principles in their class, I’m someone they can reach out to,” she said.

Johnson handles planning, setup and safety considerations involved in what can be tricky demonstrations. She makes sure the experiments happen without issue and help cement student learning. In that sense, Johnson is one of the many behind-the-scenes contributors to student learning at Brown. It's a largely hidden role in which she says she finds both comfort and fulfillment.

“I'm happy to be part of the process of helping students understand physics and making it more tangible for them,” Johnson said. “My work acts almost like a scaffold, helping support lectures so students can get the most out of them.”

The 'Demos'

Johnson joined Brown’s physics department in 2020. She has a bachelor’s degree in physics, a master’s in building science and years of experience working in in laboratories. Initially, she stumbled into being a physics demonstration manager at the University of Southern California.

“I didn't know a job like this existed, but thought that I could totally do this with my background,” Johnson said. “Science was always on my mind.”

At Brown, Johnson and a crew of students she works with run, set up and support dozens of demonstrations each semester. The demonstrations touch on what faculty in the department are teaching, ranging from astronomy to condensed matter theory. Some have involved gyroscopes, lasers, magnetic levitation, electric circuitry and cooling superfluid helium until the bubbling liquid is completely still.

Demonstrations where professors take some risks tend to be a hit, Johnson said.

For instance, when Li conducted a demonstration known as “the nose basher,” students in the class where equally excited and anxious for him.

Johnson hung a bowling ball from a string on the ceiling for the “demo.” Li then held the ball to his face and let it go. The ball swung like a pendulum and came back toward Li's face. The law of energy conservation saved him. It didn’t go beyond the point at which he initially let it go. The students who didn’t cover their eyes let out a collective sigh of relief. Many walked away better understanding the lesson.

“That was definitely a higher-stake one, so I was really invested in it,” said Rishika Kartik, a first-year student taking Li’s course. “Physics as a subject is kind of abstract, so to be able to see it gets me more curious about the subject. It helps me visualize what I’m learning, not to mention that the demonstrations are pretty entertaining and creative, so it makes the content a lot more memorable… I feel like I'm able to then notice other things in my physical world that relate back to these physics concepts. It helps me start to make connections outside of class.”

Achieving Consistency

The work is meticulous and daunting at times because of the level of precision required. Johnson often brings students aboard to assist, and they play key roles in making the demonstrations possible. The work also offers an outlet for students to get hands-on experience running experiments and mastering troubleshooting in real time.

“When the demos don't work, we always come up with alternate solutions to either fix the demo or still demonstrate the phenomenon,” said Brown junior Uri Dickman, who’s worked with Johnson since last year.

Johnson and her students sometimes spend weeks, or even summers, perfecting particular demonstrations. Since August, they have been working on how to make a new demonstration called acoustic levitation work. It involves suspending matter in the air using high-intensity sound waves.

This semester, Johnson along with first-year master’s student Shi Yan have been spending the majority of their down time trying to get the demonstration to work. They’ve built the device, aligned the speakers and even customized parts for the device in the machine shop. Progress is deliberate, but they've been able to get some of the material to levitate.

First year master’s student Shi Yan has been working with Johnson to develop a new demonstration called acoustic levitation since August. The acoustic levitation demonstration involves suspending matter in the air using high intensity sound waves.

Without this type of time investment, effort and attention to detail, many of the demonstrations won’t work. Some could quickly go wrong. There’s a reason the bowling ball demonstration is known as the nose basher, for example.

The goal is consistency and replicability, Johnson said. She needs to be able to take the results she gets from her lab to the classrooms. It’s why she’s practices set-ups, tinkers with ways to make them more efficient and always considers how they look to students in the classrooms.

Johnson often instructs faculty members how to perform the demonstrations, but some are too complex. These she chooses to do herself. Even then, they can still be finicky. The payoff is always worth it though, she says. In fact, the success leads to moments when she’s happy to be out from behind the scenes.

“In the beginning of the semester, students are always thinking ‘who is this woman coming in?’” Johnson said. “‘What is she doing?’ By the middle or close to the end, they're happy to see me. They eventually recognize, ‘OK, she's here to set up the cool stuff.”