My teenager asked me to teach him to program this summer, here's my plan

I'd say if your gonna acquire a machine, if you can get one not off a scalper, get a Pi. You can do the thing with introducing linux. You can do web development on it. You can play with databases on it. You can also play around hardware and GPIO pins so you can teach a more diverse set of programming or have the option to delve into a much more diverse set. And perhaps your teenager will find an area they like best. Perhaps they really like twiddling bits on the GPIO and want to make a device. Perhaps they like the web programming. Perhaps your teenage ends up rolling some service on their own they find useful and they can at the end of the summer throw it in a corner somewhere and interact with it from another computer and it won't take much space.

Any suggestions on direction that I can get from the HN crowd would be much appreciated. I've been wrestling with the best way to do this for a couple of months now.