Physics bugs to the rescue! How Hexbugs help students model key concepts

The COVID-19 pandemic and associated lockdowns forced many university students off-campus and into their homes for an extended period. But how are students expected to be able to participate in laboratory-based subjects, like undergraduate physics, from a computer screen?

One innovative answer came in the form of some small robotic bugs, known as Hexbug Nanos ™.

Students from Pomona College in California, armed only with a bunch of Hexbug Nanos posted to them by the course organisers, a smart phone, and common objects found around the home, were able to engage in scientific research from their houses.

In particular, the little robots enabled the undergraduate students to model concepts which are notoriously tricky to visualise, such as laws dictating the movement of electrons in a wire and the behaviour of gasses under temperature and pressure.

“We found that the pandemic-inspired reliance on simple, home-built experiments, while de-emphasizing the use of sophisticated equipment, enabled students to more effectively achieve laboratory learning objectives such as designing, implementing, and troubleshooting an experimental apparatus,” says Professor Janice Hudgins, who co-authored the research paper published in the American Journal of Physics which outlines the novel teaching method.

Students started off with a simple experiment demonstrating the ideal gas law which describes how pressure, volume and temperature of a gas are related. They used a rectangular cardboard box and a moveable partition to split the box into two chambers. A different number of bugs were put in each side and allowed to move around freely. As bugs bumped into the wall, it would move.

In this scenario, the bugs represented molecules of gas bouncing around, with the chamber containing more bugs representing a higher-pressure gas.

By videoing the process, students could track the movement of the partition over time and could visualise the behaviour of the system as the gasses finally came to an equilibrium – a point where the pressures in the two chambers equalised.

Molecules in an ideal gas bounce off the walls and each other in a chamber. Hexbugs Nano were used to simulate this. Credit: Science Photo Library/Getty Images

After gaining experience with the Hexbugs by modelling an ideal gas, the students then embarked on a semester-long research project to investigate typical statistical mechanics and electrical conduction concepts. The Drude model is a concept in classical mechanics which describes the movement of electrons in a metal wire and students modelled this by releasing the Hexbug “electrons” at the top of a tilted box, noting how they were scattered on their journey to the bottom by ‘defects’ in the metal – represented by small cardboard rings fixed to the box.

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“The Hexbug experiment provides a clearly visible, macroscale model of carrier transport in a wire that is consistent with the Drude model,” Hudgings said.

The researchers suggest that creative use of simple equipment like Hexbugs to demonstrate key concepts is an effective way to engage students and allow them to perform investigative research, whether in the laboratory or at home, and can be easily adapted to other similar subjects such as biology, biophysics, physical chemistry and electromagnetism.