The time I tried to train a non-technical co-worker for a technical role
In the 80's I worked at an EDA company (Electronic Design Automation) where I specialized in the application tools that did place and route for printed circuit boards. As a headquarters applications engineer my day to day job was handling tech support cases for both customers and field applications engineers.
The company I worked for was having trouble hiring people into my role with a strong technical background and decided to experiment with training bright non-technical folks enough to handle some of the easier cases.
We had hired one such person to handle PC configuration cases. This was in the days before "plug and play" hardware, where you had to manually configure port usage for any hardware used by the application. The new hire excelled in that role of handling PC configuration cases, so my manager decided to see if they could start handling application tool issues as well.
EDA tools for printed circuit tool design aren't terribly complicated. I had an engineering degree, but anyone with an electronics technician level of understanding could probably handle the job well and we were hoping we could train our seemingly bright new hire into handling that role. So they were sent to a training class on the application tools and as tech lead for the tool support group, I was tasked with answering any questions they had about the tools outside the training.
So one day they came to my cube and asked me to explain something about "vias". This surprised me a bit because vias are a fairly simple concept. A hole is drilled in the PCB and then metal plated so that it makes electrical contact with any printed wire traces that touch the same X-Y coordinates on various layers of the PCB. It's how an electrical connection moves from one layer to another.
So I bring up a PCB design on the workstation on my desk and start to explain this, and as I discuss the topic with the NH, it becomes apparent that they not only don't understand how a via works, they also don't understand how a wire works. So I take a step back and start to explain what a wire's role is in an electronic circuit. You have a driver and one or more loads and the wire by virtue of its conductivity passes the signal from the driver to the loads. and the various signal paths can't touch each other or the signals would get crossed. They're not getting it.
So next I decide to use an analogy to something more familiar to them. I explain that it's just like plumbing. You have a hot water source (driver) and a cold water source and they each use separate pipes (wires) to reach their respective loads and those pipes can't intersect each other just like wires can't. But it turns out that the NH doesn't understand plumbing any better than they understand electronics.
At that point I'm getting flustered and I tried to figure out how how to make this even easier to understand. I decide the wires are now hallways in a building, and the vias are stairways between hallways on different floors and there are multiple sets of hallways that people can use without ever running into the people in the other sets of hallways. For some reason that didn't work either.
At that point I had to explain that this wasn't going to work out because it gets a lot more complicated than this. My co-worker went back to their PC configuration role. We had previously had a good relationship, but they held a grudge against me until the day they were laid off, possibly longer, because I couldn't properly explain wires to them.