The first time I taught a class on my own, I came in with a lesson built for students who already knew the basics. Ten minutes in, I realized most of the room had never used the software the lesson depended on. I threw out the plan and started the next week again, from the beginning.

That class shaped how I teach. The better I know something, the harder it is to remember not knowing it, so I plan each session from where students actually are. I also keep the cost of being wrong low, because students only take risks when a mistake is cheap.

I have since taught on two continents, and I judge a class by one thing: what students do when I am not in the room.