Have them root their devices. It's not necessarily an easy thing to do, and in some cases requires CLI. It will show them a high level view of the different thing a person needs to even be able to root a device (vulnerability, code, communicating with the device etc). Talk about the ethics involved in rooting the device (yours vs theirs mentality). Flash a custom "ROM."
Success can be measured by those who successfully flash a ROM without bricking the device. This will give valuable real world experience that can at the least, teach them the perils of bricking a device. Better yet, could help them save big bucks by not bricking one of their own devices. Might even get some of them interested in computer security, vulnerability discovery/patching, and some may even start a business to root devices for customers!
But don't underestimate the ability to assemble and understand a PC down to its memory and CPU. Maybe you can have different teams cooperate to be part of a work place environment. PC building, network building, and "support" getting devices imaged and/or up and running on said network.